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2022-10-20blktrace: remove unnessary stop block trace in 'blk_trace_shutdown'Ye Bin1-3/+1
As previous commit, 'blk_trace_cleanup' will stop block trace if block trace's state is 'Blktrace_running'. So remove unnessary stop block trace in 'blk_trace_shutdown'. Signed-off-by: Ye Bin <yebin10@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221019033602.752383-4-yebin@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-20blktrace: fix possible memleak in '__blk_trace_remove'Ye Bin1-2/+2
When test as follows: step1: ioctl(sda, BLKTRACESETUP, &arg) step2: ioctl(sda, BLKTRACESTART, NULL) step3: ioctl(sda, BLKTRACETEARDOWN, NULL) step4: ioctl(sda, BLKTRACESETUP, &arg) Got issue as follows: debugfs: File 'dropped' in directory 'sda' already present! debugfs: File 'msg' in directory 'sda' already present! debugfs: File 'trace0' in directory 'sda' already present! And also find syzkaller report issue like "KASAN: use-after-free Read in relay_switch_subbuf" "https://syzkaller.appspot.com/bug?id=13849f0d9b1b818b087341691be6cc3ac6a6bfb7" If remove block trace without stop(BLKTRACESTOP) block trace, '__blk_trace_remove' will just set 'q->blk_trace' with NULL. However, debugfs file isn't removed, so will report file already present when call BLKTRACESETUP. static int __blk_trace_remove(struct request_queue *q) { struct blk_trace *bt; bt = rcu_replace_pointer(q->blk_trace, NULL, lockdep_is_held(&q->debugfs_mutex)); if (!bt) return -EINVAL; if (bt->trace_state != Blktrace_running) blk_trace_cleanup(q, bt); return 0; } If do test as follows: step1: ioctl(sda, BLKTRACESETUP, &arg) step2: ioctl(sda, BLKTRACESTART, NULL) step3: ioctl(sda, BLKTRACETEARDOWN, NULL) step4: remove sda There will remove debugfs directory which will remove recursively all file under directory. >> blk_release_queue >> debugfs_remove_recursive(q->debugfs_dir) So all files which created in 'do_blk_trace_setup' are removed, and 'dentry->d_inode' is NULL. But 'q->blk_trace' is still in 'running_trace_lock', 'trace_note_tsk' will traverse 'running_trace_lock' all nodes. >>trace_note_tsk >> trace_note >> relay_reserve >> relay_switch_subbuf >> d_inode(buf->dentry)->i_size To solve above issues, reference commit '5afedf670caf', call 'blk_trace_cleanup' unconditionally in '__blk_trace_remove' and first stop block trace in 'blk_trace_cleanup'. Signed-off-by: Ye Bin <yebin10@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221019033602.752383-3-yebin@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-20blktrace: introduce 'blk_trace_{start,stop}' helperYe Bin1-38/+36
Introduce 'blk_trace_{start,stop}' helper. No functional changed. Signed-off-by: Ye Bin <yebin10@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221019033602.752383-2-yebin@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-15blktrace: Fix the blk_fill_rwbs() kernel-doc headerBart Van Assche1-3/+3
Reflect recent changes in the blk_fill_rwbs() kernel-doc header. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Christoph Hellwig <hch@lst.de> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Chaitanya Kulkarni <kch@nvidia.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Fixes: 919dbca8670d ("blktrace: Use the new blk_opf_t type") Signed-off-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20220715184735.2326034-3-bvanassche@acm.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-14blktrace: Use the new blk_opf_t typeBart Van Assche1-26/+25
Improve static type checking by using the new blk_opf_t type for a function argument that represents a combination of a request operation and request flags. Rename that argument from 'op' into 'opf' to make its role more clear. Cc: Christoph Hellwig <hch@lst.de> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Chaitanya Kulkarni <kch@nvidia.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20220714180729.1065367-12-bvanassche@acm.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-14blktrace: Trace remapped requests correctlyBart Van Assche1-1/+1
Trace the remapped operation and its flags instead of only the data direction of remapped operations. This issue was detected by analyzing the warnings reported by sparse related to the new blk_opf_t type. Reviewed-by: Jun'ichi Nomura <junichi.nomura@nec.com> Cc: Mike Snitzer <snitzer@kernel.org> Cc: Mike Christie <michael.christie@oracle.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Chaitanya Kulkarni <kch@nvidia.com> Fixes: 1b9a9ab78b0a ("blktrace: use op accessors") Signed-off-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20220714180729.1065367-11-bvanassche@acm.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-14block: remove bdevnameChristoph Hellwig1-2/+2
Replace the remaining calls of bdevname with snprintf using the %pg format specifier. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20220713055317.1888500-10-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-06-28block: simplify blktrace sysfs attribute creationChristoph Hellwig1-11/+0
Add the trace attributes to the default gendisk attributes, just like we already do for partitions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20220628171850.1313069-2-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-06-17block: serialize all debugfs operations using q->debugfs_mutexChristoph Hellwig1-3/+0
Various places like I/O schedulers or the QOS infrastructure try to register debugfs files on demans, which can race with creating and removing the main queue debugfs directory. Use the existing debugfs_mutex to serialize all debugfs operations that rely on q->debugfs_dir or the directories hanging off it. To make the teardown code a little simpler declare all debugfs dentry pointers and not just the main one uncoditionally in blkdev.h. Move debugfs_mutex next to the dentries that it protects and document what it is used for. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220614074827.458955-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-05-02blk-cgroup: replace bio_blkcg with bio_blkcg_cssChristoph Hellwig1-2/+4
All callers of bio_blkcg actually want the CSS, so replace it with an interface that does return the CSS. This now allows to move struct blkcg_gq to block/blk-cgroup.h instead of exposing it in a public header. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20220420042723.1010598-10-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-05-02blktrace: cleanup the __trace_note_message interfaceChristoph Hellwig1-10/+10
Pass the cgroup_subsys_state instead of a the blkg so that blktrace doesn't need to poke into blk-cgroup internals, and give the name a blk prefix as the current name is way too generic for a public interface. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20220420042723.1010598-9-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-24Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsiLinus Torvalds1-1/+0
Pull SCSI updates from James Bottomley: "This series consists of the usual driver updates (qla2xxx, pm8001, libsas, smartpqi, scsi_debug, lpfc, iscsi, mpi3mr) plus minor updates and bug fixes. The high blast radius core update is the removal of write same, which affects block and several non-SCSI devices. The other big change, which is more local, is the removal of the SCSI pointer" * tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (281 commits) scsi: scsi_ioctl: Drop needless assignment in sg_io() scsi: bsg: Drop needless assignment in scsi_bsg_sg_io_fn() scsi: lpfc: Copyright updates for 14.2.0.0 patches scsi: lpfc: Update lpfc version to 14.2.0.0 scsi: lpfc: SLI path split: Refactor BSG paths scsi: lpfc: SLI path split: Refactor Abort paths scsi: lpfc: SLI path split: Refactor SCSI paths scsi: lpfc: SLI path split: Refactor CT paths scsi: lpfc: SLI path split: Refactor misc ELS paths scsi: lpfc: SLI path split: Refactor VMID paths scsi: lpfc: SLI path split: Refactor FDISC paths scsi: lpfc: SLI path split: Refactor LS_RJT paths scsi: lpfc: SLI path split: Refactor LS_ACC paths scsi: lpfc: SLI path split: Refactor the RSCN/SCR/RDF/EDC/FARPR paths scsi: lpfc: SLI path split: Refactor PLOGI/PRLI/ADISC/LOGO paths scsi: lpfc: SLI path split: Refactor base ELS paths and the FLOGI path scsi: lpfc: SLI path split: Introduce lpfc_prep_wqe scsi: lpfc: SLI path split: Refactor fast and slow paths to native SLI4 scsi: lpfc: SLI path split: Refactor lpfc_iocbq scsi: lpfc: Use kcalloc() ...
2022-02-28blktrace: fix use after free for struct blk_traceYu Kuai1-8/+18
When tracing the whole disk, 'dropped' and 'msg' will be created under 'q->debugfs_dir' and 'bt->dir' is NULL, thus blk_trace_free() won't remove those files. What's worse, the following UAF can be triggered because of accessing stale 'dropped' and 'msg': ================================================================== BUG: KASAN: use-after-free in blk_dropped_read+0x89/0x100 Read of size 4 at addr ffff88816912f3d8 by task blktrace/1188 CPU: 27 PID: 1188 Comm: blktrace Not tainted 5.17.0-rc4-next-20220217+ #469 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-4 Call Trace: <TASK> dump_stack_lvl+0x34/0x44 print_address_description.constprop.0.cold+0xab/0x381 ? blk_dropped_read+0x89/0x100 ? blk_dropped_read+0x89/0x100 kasan_report.cold+0x83/0xdf ? blk_dropped_read+0x89/0x100 kasan_check_range+0x140/0x1b0 blk_dropped_read+0x89/0x100 ? blk_create_buf_file_callback+0x20/0x20 ? kmem_cache_free+0xa1/0x500 ? do_sys_openat2+0x258/0x460 full_proxy_read+0x8f/0xc0 vfs_read+0xc6/0x260 ksys_read+0xb9/0x150 ? vfs_write+0x3d0/0x3d0 ? fpregs_assert_state_consistent+0x55/0x60 ? exit_to_user_mode_prepare+0x39/0x1e0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fbc080d92fd Code: ce 20 00 00 75 10 b8 00 00 00 00 0f 05 48 3d 01 f0 ff ff 73 31 c3 48 83 1 RSP: 002b:00007fbb95ff9cb0 EFLAGS: 00000293 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007fbb95ff9dc0 RCX: 00007fbc080d92fd RDX: 0000000000000100 RSI: 00007fbb95ff9cc0 RDI: 0000000000000045 RBP: 0000000000000045 R08: 0000000000406299 R09: 00000000fffffffd R10: 000000000153afa0 R11: 0000000000000293 R12: 00007fbb780008c0 R13: 00007fbb78000938 R14: 0000000000608b30 R15: 00007fbb780029c8 </TASK> Allocated by task 1050: kasan_save_stack+0x1e/0x40 __kasan_kmalloc+0x81/0xa0 do_blk_trace_setup+0xcb/0x410 __blk_trace_setup+0xac/0x130 blk_trace_ioctl+0xe9/0x1c0 blkdev_ioctl+0xf1/0x390 __x64_sys_ioctl+0xa5/0xe0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae Freed by task 1050: kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 kasan_set_free_info+0x20/0x30 __kasan_slab_free+0x103/0x180 kfree+0x9a/0x4c0 __blk_trace_remove+0x53/0x70 blk_trace_ioctl+0x199/0x1c0 blkdev_common_ioctl+0x5e9/0xb30 blkdev_ioctl+0x1a5/0x390 __x64_sys_ioctl+0xa5/0xe0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff88816912f380 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 88 bytes inside of 96-byte region [ffff88816912f380, ffff88816912f3e0) The buggy address belongs to the page: page:000000009a1b4e7c refcount:1 mapcount:0 mapping:0000000000000000 index:0x0f flags: 0x17ffffc0000200(slab|node=0|zone=2|lastcpupid=0x1fffff) raw: 0017ffffc0000200 ffffea00044f1100 dead000000000002 ffff88810004c780 raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88816912f280: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff88816912f300: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc >ffff88816912f380: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff88816912f400: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff88816912f480: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ================================================================== Fixes: c0ea57608b69 ("blktrace: remove debugfs file dentries from struct blk_trace") Signed-off-by: Yu Kuai <yukuai3@huawei.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/r/20220228034354.4047385-1-yukuai3@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-22scsi: block: Remove REQ_OP_WRITE_SAME supportChristoph Hellwig1-1/+0
No more users of REQ_OP_WRITE_SAME or drivers implementing it are left, so remove the infrastructure. [mkp: fold in and tweak sysfs reporting fix] Link: https://lore.kernel.org/r/20220209082828.2629273-8-hch@lst.de Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2021-12-20blktrace: switch trace spinlock to a raw spinlockWander Lairson Costa1-9/+9
The running_trace_lock protects running_trace_list and is acquired within the tracepoint which implies disabled preemption. The spinlock_t typed lock can not be acquired with disabled preemption on PREEMPT_RT because it becomes a sleeping lock. The runtime of the tracepoint depends on the number of entries in running_trace_list and has no limit. The blk-tracer is considered debug code and higher latencies here are okay. Make running_trace_lock a raw_spinlock_t. Signed-off-by: Wander Lairson Costa <wander@redhat.com> Link: https://lore.kernel.org/r/20211220192827.38297-1-wander@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29block: remove the ->rq_disk field in struct requestChristoph Hellwig1-1/+1
Just use the disk attached to the request_queue instead. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Link: https://lore.kernel.org/r/20211126121802.2090656-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-10-19block: don't call blk_status_to_errno in blk_update_requestChristoph Hellwig1-3/+4
We only need to call it to resolve the blk_status_t -> errno mapping for tracing, so move the conversion into the tracepoints that are not called at all when tracing isn't enabled. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-09-24blktrace: Fix uaf in blk_trace access after removing by sysfsZhihao Cheng1-0/+8
There is an use-after-free problem triggered by following process: P1(sda) P2(sdb) echo 0 > /sys/block/sdb/trace/enable blk_trace_remove_queue synchronize_rcu blk_trace_free relay_close rcu_read_lock __blk_add_trace trace_note_tsk (Iterate running_trace_list) relay_close_buf relay_destroy_buf kfree(buf) trace_note(sdb's bt) relay_reserve buf->offset <- nullptr deference (use-after-free) !!! rcu_read_unlock [ 502.714379] BUG: kernel NULL pointer dereference, address: 0000000000000010 [ 502.715260] #PF: supervisor read access in kernel mode [ 502.715903] #PF: error_code(0x0000) - not-present page [ 502.716546] PGD 103984067 P4D 103984067 PUD 17592b067 PMD 0 [ 502.717252] Oops: 0000 [#1] SMP [ 502.720308] RIP: 0010:trace_note.isra.0+0x86/0x360 [ 502.732872] Call Trace: [ 502.733193] __blk_add_trace.cold+0x137/0x1a3 [ 502.733734] blk_add_trace_rq+0x7b/0xd0 [ 502.734207] blk_add_trace_rq_issue+0x54/0xa0 [ 502.734755] blk_mq_start_request+0xde/0x1b0 [ 502.735287] scsi_queue_rq+0x528/0x1140 ... [ 502.742704] sg_new_write.isra.0+0x16e/0x3e0 [ 502.747501] sg_ioctl+0x466/0x1100 Reproduce method: ioctl(/dev/sda, BLKTRACESETUP, blk_user_trace_setup[buf_size=127]) ioctl(/dev/sda, BLKTRACESTART) ioctl(/dev/sdb, BLKTRACESETUP, blk_user_trace_setup[buf_size=127]) ioctl(/dev/sdb, BLKTRACESTART) echo 0 > /sys/block/sdb/trace/enable & // Add delay(mdelay/msleep) before kernel enters blk_trace_free() ioctl$SG_IO(/dev/sda, SG_IO, ...) // Enters trace_note_tsk() after blk_trace_free() returned // Use mdelay in rcu region rather than msleep(which may schedule out) Remove blk_trace from running_list before calling blk_trace_free() by sysfs if blk_trace is at Blktrace_running state. Fixes: c71a896154119f ("blktrace: add ftrace plugin") Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com> Link: https://lore.kernel.org/r/20210923134921.109194-1-chengzhihao1@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-02-28Merge tag 'block-5.12-2021-02-27' of git://git.kernel.dk/linux-blockLinus Torvalds1-7/+13
Pull more block updates from Jens Axboe: "A few stragglers (and one due to me missing it originally), and fixes for changes in this merge window mostly. In particular: - blktrace cleanups (Chaitanya, Greg) - Kill dead blk_pm_* functions (Bart) - Fixes for the bio alloc changes (Christoph) - Fix for the partition changes (Christoph, Ming) - Fix for turning off iopoll with polled IO inflight (Jeffle) - nbd disconnect fix (Josef) - loop fsync error fix (Mauricio) - kyber update depth fix (Yang) - max_sectors alignment fix (Mikulas) - Add bio_max_segs helper (Matthew)" * tag 'block-5.12-2021-02-27' of git://git.kernel.dk/linux-block: (21 commits) block: Add bio_max_segs blktrace: fix documentation for blk_fill_rw() block: memory allocations in bounce_clone_bio must not fail block: remove the gfp_mask argument to bounce_clone_bio block: fix bounce_clone_bio for passthrough bios block-crypto-fallback: use a bio_set for splitting bios block: fix logging on capacity change blk-settings: align max_sectors on "logical_block_size" boundary block: reopen the device in blkdev_reread_part block: don't skip empty device in in disk_uevent blktrace: remove debugfs file dentries from struct blk_trace nbd: handle device refs for DESTROY_ON_DISCONNECT properly kyber: introduce kyber_depth_updated() loop: fix I/O error on fsync() in detached loop devices block: fix potential IO hang when turning off io_poll block: get rid of the trace rq insert wrapper blktrace: fix blk_rq_merge documentation blktrace: fix blk_rq_issue documentation blktrace: add blk_fill_rwbs documentation comment block: remove superfluous param in blk_fill_rwbs() ...
2021-02-24blktrace: fix documentation for blk_fill_rw()Chaitanya Kulkarni1-1/+1
Add missing ":" after rwbs function parameter documentation that fixes following warning :- ./kernel/trace/blktrace.c:1877: warning: Function parameter or member 'rwbs' not described in 'blk_fill_rwbs' Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Fixes: 1f83bb4b4914 ("blktrace: add blk_fill_rwbs documentation comment") Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-02-23blktrace: remove debugfs file dentries from struct blk_traceGreg Kroah-Hartman1-6/+2
These debugfs dentries do not need to be saved for anything as the whole directory and everything in it is properly cleaned up when the parent directory is removed. So remove them from struct blk_trace and don't save them when created as it's not necessary. Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: linux-block@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-02-22Merge tag 'trace-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-traceLinus Torvalds1-8/+9
Pull tracing updates from Steven Rostedt: - Update to the way irqs and preemption is tracked via the trace event PC field - Fix handling of unregistering event failing due to allocate memory. This is only triggered by failure injection, as it is pretty much guaranteed to have less than a page allocation succeed. - Do not show the useless "filter" or "enable" files for the "ftrace" trace system, as they have no effect on doing anything. - Add a warning if kprobes are registered more than once. - Synthetic events now have their fields parsed by semicolons. Old formats without semicolons will still work, but new features will require them. - New option to allow trace events to show %p without hashing in trace file. The trace file can only be read by root, and reading the raw event buffer did not have any pointers hashed, so this does not expose anything new. - New directory in tools called tools/tracing, where a new tool that reads sequential latency reports from the ftrace latency tracers. - Other minor fixes and cleanups. * tag 'trace-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (33 commits) kprobes: Fix to delay the kprobes jump optimization tracing/tools: Add the latency-collector to tools directory tracing: Make hash-ptr option default tracing: Add ptr-hash option to show the hashed pointer value tracing: Update the stage 3 of trace event macro comment tracing: Show real address for trace event arguments selftests/ftrace: Add '!event' synthetic event syntax check selftests/ftrace: Update synthetic event syntax errors tracing: Add a backward-compatibility check for synthetic event creation tracing: Update synth command errors tracing: Rework synthetic event command parsing tracing/dynevent: Delegate parsing to create function kprobes: Warn if the kprobe is reregistered ftrace: Remove unused ftrace_force_update() tracepoints: Code clean up tracepoints: Do not punish non static call users tracepoints: Remove unnecessary "data_args" macro parameter tracing: Do not create "enable" or "filter" files for ftrace event subsystem kernel: trace: preemptirq_delay_test: add cpu affinity tracepoint: Do not fail unregistering a probe due to memory failure ...
2021-02-22blktrace: add blk_fill_rwbs documentation commentChaitanya Kulkarni1-0/+10
blk_fill_rwbs() is an expoted function, add kernel style documentation comment. Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-02-22block: remove superfluous param in blk_fill_rwbs()Chaitanya Kulkarni1-1/+1
The last parameter for the function blk_fill_rwbs() was added in 5782138e47 ("tracing/events: convert block trace points to TRACE_EVENT()") in order to signal read request and use of that parameter was replaced with using switch case REQ_OP_READ with 1b9a9ab78b0 ("blktrace: use op accessors"), but the parameter was never removed. Remove the unused parameter and adjust the respective call sites. Fixes: 1b9a9ab78b0 ("blktrace: use op accessors") Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-02-02tracing: Merge irqflags + preempt counter.Sebastian Andrzej Siewior1-8/+9
The state of the interrupts (irqflags) and the preemption counter are both passed down to tracing_generic_entry_update(). Only one bit of irqflags is actually required: The on/off state. The complete 32bit of the preemption counter isn't needed. Just whether of the upper bits (softirq, hardirq and NMI) are set and the preemption depth is needed. The irqflags and the preemption counter could be evaluated early and the information stored in an integer `trace_ctx'. tracing_generic_entry_update() would use the upper bits as the TRACE_FLAG_* and the lower 8bit as the disabled-preemption depth (considering that one must be substracted from the counter in one special cases). The actual preemption value is not used except for the tracing record. The `irqflags' variable is mostly used only for the tracing record. An exception here is for instance wakeup_tracer_call() or probe_wakeup_sched_switch() which explicilty disable interrupts and use that `irqflags' to save (and restore) the IRQ state and to record the state. Struct trace_event_buffer has also the `pc' and flags' members which can be replaced with `trace_ctx' since their actual value is not used outside of trace recording. This will reduce tracing_generic_entry_update() to simply assign values to struct trace_entry. The evaluation of the TRACE_FLAG_* bits is moved to _tracing_gen_ctx_flags() which replaces preempt_count() and local_save_flags() invocations. As an example, ftrace_syscall_enter() may invoke: - trace_buffer_lock_reserve() -> … -> tracing_generic_entry_update() - event_trigger_unlock_commit() -> ftrace_trace_stack() -> … -> tracing_generic_entry_update() -> ftrace_trace_userstack() -> … -> tracing_generic_entry_update() In this case the TRACE_FLAG_* bits were evaluated three times. By using the `trace_ctx' they are evaluated once and assigned three times. A build with all tracers enabled on x86-64 with and without the patch: text data bss dec hex filename 21970669 17084168 7639260 46694097 2c87ed1 vmlinux.old 21970293 17084168 7639260 46693721 2c87d59 vmlinux.new text shrank by 379 bytes, data remained constant. Link: https://lkml.kernel.org/r/20210125194511.3924915-2-bigeasy@linutronix.de Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-01-24block: store a block_device pointer in struct bioChristoph Hellwig1-7/+9
Replace the gendisk pointer in struct bio with a pointer to the newly improved struct block device. From that the gendisk can be trivially accessed with an extra indirection, but it also allows to directly look up all information related to partition remapping. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-12-17Merge tag 'trace-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-traceLinus Torvalds1-2/+2
Pull tracing updates from Steven Rostedt: "The major update to this release is that there's a new arch config option called CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS. Currently, only x86_64 enables it. All the ftrace callbacks now take a struct ftrace_regs instead of a struct pt_regs. If the architecture has HAVE_DYNAMIC_FTRACE_WITH_ARGS enabled, then the ftrace_regs will have enough information to read the arguments of the function being traced, as well as access to the stack pointer. This way, if a user (like live kernel patching) only cares about the arguments, then it can avoid using the heavier weight "regs" callback, that puts in enough information in the struct ftrace_regs to simulate a breakpoint exception (needed for kprobes). A new config option that audits the timestamps of the ftrace ring buffer at most every event recorded. Ftrace recursion protection has been cleaned up to move the protection to the callback itself (this saves on an extra function call for those callbacks). Perf now handles its own RCU protection and does not depend on ftrace to do it for it (saving on that extra function call). New debug option to add "recursed_functions" file to tracefs that lists all the places that triggered the recursion protection of the function tracer. This will show where things need to be fixed as recursion slows down the function tracer. The eval enum mapping updates done at boot up are now offloaded to a work queue, as it caused a noticeable pause on slow embedded boards. Various clean ups and last minute fixes" * tag 'trace-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (33 commits) tracing: Offload eval map updates to a work queue Revert: "ring-buffer: Remove HAVE_64BIT_ALIGNED_ACCESS" ring-buffer: Add rb_check_bpage in __rb_allocate_pages ring-buffer: Fix two typos in comments tracing: Drop unneeded assignment in ring_buffer_resize() tracing: Disable ftrace selftests when any tracer is running seq_buf: Avoid type mismatch for seq_buf_init ring-buffer: Fix a typo in function description ring-buffer: Remove obsolete rb_event_is_commit() ring-buffer: Add test to validate the time stamp deltas ftrace/documentation: Fix RST C code blocks tracing: Clean up after filter logic rewriting tracing: Remove the useless value assignment in test_create_synth_event() livepatch: Use the default ftrace_ops instead of REGS when ARGS is available ftrace/x86: Allow for arguments to be passed in to ftrace_regs by default ftrace: Have the callbacks receive a struct ftrace_regs instead of pt_regs MAINTAINERS: assign ./fs/tracefs to TRACING tracing: Fix some typos in comments ftrace: Remove unused varible 'ret' ring-buffer: Add recording of ring buffer recursion into recursed_functions ...
2020-12-16Merge tag 'for-5.11/block-2020-12-14' of git://git.kernel.dk/linux-blockLinus Torvalds1-136/+45
Pull block updates from Jens Axboe: "Another series of killing more code than what is being added, again thanks to Christoph's relentless cleanups and tech debt tackling. This contains: - blk-iocost improvements (Baolin Wang) - part0 iostat fix (Jeffle Xu) - Disable iopoll for split bios (Jeffle Xu) - block tracepoint cleanups (Christoph Hellwig) - Merging of struct block_device and hd_struct (Christoph Hellwig) - Rework/cleanup of how block device sizes are updated (Christoph Hellwig) - Simplification of gendisk lookup and removal of block device aliasing (Christoph Hellwig) - Block device ioctl cleanups (Christoph Hellwig) - Removal of bdget()/blkdev_get() as exported API (Christoph Hellwig) - Disk change rework, avoid ->revalidate_disk() (Christoph Hellwig) - sbitmap improvements (Pavel Begunkov) - Hybrid polling fix (Pavel Begunkov) - bvec iteration improvements (Pavel Begunkov) - Zone revalidation fixes (Damien Le Moal) - blk-throttle limit fix (Yu Kuai) - Various little fixes" * tag 'for-5.11/block-2020-12-14' of git://git.kernel.dk/linux-block: (126 commits) blk-mq: fix msec comment from micro to milli seconds blk-mq: update arg in comment of blk_mq_map_queue blk-mq: add helper allocating tagset->tags Revert "block: Fix a lockdep complaint triggered by request queue flushing" nvme-loop: use blk_mq_hctx_set_fq_lock_class to set loop's lock class blk-mq: add new API of blk_mq_hctx_set_fq_lock_class block: disable iopoll for split bio block: Improve blk_revalidate_disk_zones() checks sbitmap: simplify wrap check sbitmap: replace CAS with atomic and sbitmap: remove swap_lock sbitmap: optimise sbitmap_deferred_clear() blk-mq: skip hybrid polling if iopoll doesn't spin blk-iocost: Factor out the base vrate change into a separate function blk-iocost: Factor out the active iocgs' state check into a separate function blk-iocost: Move the usage ratio calculation to the correct place blk-iocost: Remove unnecessary advance declaration blk-iocost: Fix some typos in comments blktrace: fix up a kerneldoc comment block: remove the request_queue to argument request based tracepoints ...
2020-12-15blktrace: make relay callbacks constJani Nikula1-1/+1
Now that relay_open() accepts const callbacks, make relay callbacks const. Link: https://lkml.kernel.org/r/7ff5ce0b735901eb4f10e13da2704f1d8c4a2507.1606153547.git.jani.nikula@intel.com Signed-off-by: Jani Nikula <jani.nikula@intel.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Jens Axboe <axboe@kernel.dk> Cc: Kalle Valo <kvalo@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-07blktrace: fix up a kerneldoc commentChristoph Hellwig1-1/+0
Fixes: a54895fa057c ("block: remove the request_queue to argument request based tracepoints") Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-12-04block: remove the request_queue to argument request based tracepointsChristoph Hellwig1-27/+17
The request_queue can trivially be derived from the request. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-12-04block: remove the request_queue argument to the block_bio_remap tracepointChristoph Hellwig1-9/+5
The request_queue can trivially be derived from the bio. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-12-04block: remove the request_queue argument to the block_split tracepointChristoph Hellwig1-3/+2
The request_queue can trivially be derived from the bio. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-12-04block: simplify and extend the block_bio_merge tracepoint classChristoph Hellwig1-31/+10
The block_bio_merge tracepoint class can be reused for most bio-based tracepoints. For that it just needs to lose the superfluous q and rq parameters. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-12-04block: remove the unused block_sleeprq tracepointChristoph Hellwig1-22/+0
The block_sleeprq tracepoint was only used by the legacy request code. Remove it now that the legacy request code is gone. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-12-01block: merge struct block_device and struct hd_structChristoph Hellwig1-35/+8
Instead of having two structures that represent each block device with different life time rules, merge them into a single one. This also greatly simplifies the reference counting rules, as we can use the inode reference count as the main reference count for the new struct block_device, with the device model reference front ending it for device model interaction. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-12-01block: move the start_sect field to struct block_deviceChristoph Hellwig1-8/+3
Move the start_sect field to struct block_device in preparation of killing struct hd_struct. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-12-01block: remove the nr_sects field in struct hd_structChristoph Hellwig1-1/+1
Now that the hd_struct always has a block device attached to it, there is no need for having two size field that just get out of sync. Additionally the field in hd_struct did not use proper serialization, possibly allowing for torn writes. By only using the block_device field this problem also gets fixed. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Coly Li <colyli@suse.de> [bcache] Acked-by: Chao Yu <yuchao0@huawei.com> [f2fs] Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-11-10tracing: Fix some typos in commentsQiujun Huang1-2/+2
s/detetector/detector/ s/enfoced/enforced/ s/writen/written/ s/actualy/actually/ s/bascially/basically/ s/Regarldess/Regardless/ s/zeroes/zeros/ s/followd/followed/ s/incrememented/incremented/ s/separatelly/separately/ s/accesible/accessible/ s/sythetic/synthetic/ s/enabed/enabled/ s/heurisitc/heuristic/ s/assocated/associated/ s/otherwides/otherwise/ s/specfied/specified/ s/seaching/searching/ s/hierachry/hierarchy/ s/internel/internal/ s/Thise/This/ Link: https://lkml.kernel.org/r/20201029150554.3354-1-hqjagain@gmail.com Signed-off-by: Qiujun Huang <hqjagain@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-10-05block: add a bdget_part helperChristoph Hellwig1-7/+2
All remaining callers of bdget() outside of fs/block_dev.c want to get a reference to the struct block_device for a given struct hd_struct. Add a helper just for that and then mark bdget static. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-25block: add a bdev_is_partition helperChristoph Hellwig1-1/+1
Add a littler helper to make the somewhat arcane bd_contains checks a little more obvious. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-07blktrace: make function blk_trace_bio_get_cgid() staticWang Hai1-1/+1
The sparse tool complains as follows: kernel/trace/blktrace.c:796:5: warning: symbol 'blk_trace_bio_get_cgid' was not declared. Should it be static? This function is not used outside of blktrace.c, so this commit marks it static. Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Wang Hai <wanghai38@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-08-23treewide: Use fallthrough pseudo-keywordGustavo A. R. Silva1-1/+1
Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-06-25blktrace: Provide event for request mergingJan Kara1-0/+10
Currently blk-mq does not report any event when two requests get merged in the elevator. This then results in difficult to understand sequence of events like: ... 8,0 34 1579 0.608765271 2718 I WS 215023504 + 40 [dbench] 8,0 34 1584 0.609184613 2719 A WS 215023544 + 56 <- (8,4) 2160568 8,0 34 1585 0.609184850 2719 Q WS 215023544 + 56 [dbench] 8,0 34 1586 0.609188524 2719 G WS 215023544 + 56 [dbench] 8,0 3 602 0.609684162 773 D WS 215023504 + 96 [kworker/3:1H] 8,0 34 1591 0.609843593 0 C WS 215023504 + 96 [0] and you can only guess (after quite some headscratching since the above excerpt is intermixed with a lot of other IO) that request 215023544+56 got merged to request 215023504+40. Provide proper event for request merging like we used to do in the legacy block layer. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-24block: create the request_queue debugfs_dir on registrationLuis Chamberlain1-32/+26
We were only creating the request_queue debugfs_dir only for make_request block drivers (multiqueue), but never for request-based block drivers. We did this as we were only creating non-blktrace additional debugfs files on that directory for make_request drivers. However, since blktrace *always* creates that directory anyway, we special-case the use of that directory on blktrace. Other than this being an eye-sore, this exposes request-based block drivers to the same debugfs fragile race that used to exist with make_request block drivers where if we start adding files onto that directory we can later run a race with a double removal of dentries on the directory if we don't deal with this carefully on blktrace. Instead, just simplify things by always creating the request_queue debugfs_dir on request_queue registration. Rename the mutex also to reflect the fact that this is used outside of the blktrace context. Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-24blktrace: ensure our debugfs dir existsLuis Chamberlain1-0/+12
We make an assumption that a debugfs directory exists, but since this can fail ensure it exists before allowing blktrace setup to complete. Otherwise we end up stuffing blktrace files on the debugfs root directory. In the worst case scenario this *in theory* can create an eventual panic *iff* in the future a similarly named file is created prior on the debugfs root directory. This theoretical crash can happen due to a recursive removal followed by a specific dentry removal. This doesn't fix any known crash, however I have seen the files go into the main debugfs root directory in cases where the debugfs directory was not created due to other internal bugs with blktrace now fixed. blktrace is also completely useless without this directory, so this ensures to userspace we only setup blktrace if the kernel can stuff files where they are supposed to go into. debugfs directory creations typically aren't checked for, and we have maintainers doing sweep removals of these checks, but since we need this check to ensure proper userspace blktrace functionality we make sure to annotate the justification for the check. Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-24blktrace: fix debugfs use after freeLuis Chamberlain1-6/+12
On commit 6ac93117ab00 ("blktrace: use existing disk debugfs directory") merged on v4.12 Omar fixed the original blktrace code for request-based drivers (multiqueue). This however left in place a possible crash, if you happen to abuse blktrace while racing to remove / add a device. We used to use asynchronous removal of the request_queue, and with that the issue was easier to reproduce. Now that we have reverted to synchronous removal of the request_queue, the issue is still possible to reproduce, its however just a bit more difficult. We essentially run two instances of break-blktrace which add/remove a loop device, and setup a blktrace and just never tear the blktrace down. We do this twice in parallel. This is easily reproduced with the script run_0004.sh from break-blktrace [0]. We can end up with two types of panics each reflecting where we race, one a failed blktrace setup: [ 252.426751] debugfs: Directory 'loop0' with parent 'block' already present! [ 252.432265] BUG: kernel NULL pointer dereference, address: 00000000000000a0 [ 252.436592] #PF: supervisor write access in kernel mode [ 252.439822] #PF: error_code(0x0002) - not-present page [ 252.442967] PGD 0 P4D 0 [ 252.444656] Oops: 0002 [#1] SMP NOPTI [ 252.446972] CPU: 10 PID: 1153 Comm: break-blktrace Tainted: G E 5.7.0-rc2-next-20200420+ #164 [ 252.452673] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014 [ 252.456343] RIP: 0010:down_write+0x15/0x40 [ 252.458146] Code: eb ca e8 ae 22 8d ff cc cc cc cc cc cc cc cc cc cc cc cc cc cc 0f 1f 44 00 00 55 48 89 fd e8 52 db ff ff 31 c0 ba 01 00 00 00 <f0> 48 0f b1 55 00 75 0f 48 8b 04 25 c0 8b 01 00 48 89 45 08 5d [ 252.463638] RSP: 0018:ffffa626415abcc8 EFLAGS: 00010246 [ 252.464950] RAX: 0000000000000000 RBX: ffff958c25f0f5c0 RCX: ffffff8100000000 [ 252.466727] RDX: 0000000000000001 RSI: ffffff8100000000 RDI: 00000000000000a0 [ 252.468482] RBP: 00000000000000a0 R08: 0000000000000000 R09: 0000000000000001 [ 252.470014] R10: 0000000000000000 R11: ffff958d1f9227ff R12: 0000000000000000 [ 252.471473] R13: ffff958c25ea5380 R14: ffffffff8cce15f1 R15: 00000000000000a0 [ 252.473346] FS: 00007f2e69dee540(0000) GS:ffff958c2fc80000(0000) knlGS:0000000000000000 [ 252.475225] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 252.476267] CR2: 00000000000000a0 CR3: 0000000427d10004 CR4: 0000000000360ee0 [ 252.477526] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 252.478776] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 252.479866] Call Trace: [ 252.480322] simple_recursive_removal+0x4e/0x2e0 [ 252.481078] ? debugfs_remove+0x60/0x60 [ 252.481725] ? relay_destroy_buf+0x77/0xb0 [ 252.482662] debugfs_remove+0x40/0x60 [ 252.483518] blk_remove_buf_file_callback+0x5/0x10 [ 252.484328] relay_close_buf+0x2e/0x60 [ 252.484930] relay_open+0x1ce/0x2c0 [ 252.485520] do_blk_trace_setup+0x14f/0x2b0 [ 252.486187] __blk_trace_setup+0x54/0xb0 [ 252.486803] blk_trace_ioctl+0x90/0x140 [ 252.487423] ? do_sys_openat2+0x1ab/0x2d0 [ 252.488053] blkdev_ioctl+0x4d/0x260 [ 252.488636] block_ioctl+0x39/0x40 [ 252.489139] ksys_ioctl+0x87/0xc0 [ 252.489675] __x64_sys_ioctl+0x16/0x20 [ 252.490380] do_syscall_64+0x52/0x180 [ 252.491032] entry_SYSCALL_64_after_hwframe+0x44/0xa9 And the other on the device removal: [ 128.528940] debugfs: Directory 'loop0' with parent 'block' already present! [ 128.615325] BUG: kernel NULL pointer dereference, address: 00000000000000a0 [ 128.619537] #PF: supervisor write access in kernel mode [ 128.622700] #PF: error_code(0x0002) - not-present page [ 128.625842] PGD 0 P4D 0 [ 128.627585] Oops: 0002 [#1] SMP NOPTI [ 128.629871] CPU: 12 PID: 544 Comm: break-blktrace Tainted: G E 5.7.0-rc2-next-20200420+ #164 [ 128.635595] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014 [ 128.640471] RIP: 0010:down_write+0x15/0x40 [ 128.643041] Code: eb ca e8 ae 22 8d ff cc cc cc cc cc cc cc cc cc cc cc cc cc cc 0f 1f 44 00 00 55 48 89 fd e8 52 db ff ff 31 c0 ba 01 00 00 00 <f0> 48 0f b1 55 00 75 0f 65 48 8b 04 25 c0 8b 01 00 48 89 45 08 5d [ 128.650180] RSP: 0018:ffffa9c3c05ebd78 EFLAGS: 00010246 [ 128.651820] RAX: 0000000000000000 RBX: ffff8ae9a6370240 RCX: ffffff8100000000 [ 128.653942] RDX: 0000000000000001 RSI: ffffff8100000000 RDI: 00000000000000a0 [ 128.655720] RBP: 00000000000000a0 R08: 0000000000000002 R09: ffff8ae9afd2d3d0 [ 128.657400] R10: 0000000000000056 R11: 0000000000000000 R12: 0000000000000000 [ 128.659099] R13: 0000000000000000 R14: 0000000000000003 R15: 00000000000000a0 [ 128.660500] FS: 00007febfd995540(0000) GS:ffff8ae9afd00000(0000) knlGS:0000000000000000 [ 128.662204] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 128.663426] CR2: 00000000000000a0 CR3: 0000000420042003 CR4: 0000000000360ee0 [ 128.664776] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 128.666022] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 128.667282] Call Trace: [ 128.667801] simple_recursive_removal+0x4e/0x2e0 [ 128.668663] ? debugfs_remove+0x60/0x60 [ 128.669368] debugfs_remove+0x40/0x60 [ 128.669985] blk_trace_free+0xd/0x50 [ 128.670593] __blk_trace_remove+0x27/0x40 [ 128.671274] blk_trace_shutdown+0x30/0x40 [ 128.671935] blk_release_queue+0x95/0xf0 [ 128.672589] kobject_put+0xa5/0x1b0 [ 128.673188] disk_release+0xa2/0xc0 [ 128.673786] device_release+0x28/0x80 [ 128.674376] kobject_put+0xa5/0x1b0 [ 128.674915] loop_remove+0x39/0x50 [loop] [ 128.675511] loop_control_ioctl+0x113/0x130 [loop] [ 128.676199] ksys_ioctl+0x87/0xc0 [ 128.676708] __x64_sys_ioctl+0x16/0x20 [ 128.677274] do_syscall_64+0x52/0x180 [ 128.677823] entry_SYSCALL_64_after_hwframe+0x44/0xa9 The common theme here is: debugfs: Directory 'loop0' with parent 'block' already present This crash happens because of how blktrace uses the debugfs directory where it places its files. Upon init we always create the same directory which would be needed by blktrace but we only do this for make_request drivers (multiqueue) block drivers. When you race a removal of these devices with a blktrace setup you end up in a situation where the make_request recursive debugfs removal will sweep away the blktrace files and then later blktrace will also try to remove individual dentries which are already NULL. The inverse is also possible and hence the two types of use after frees. We don't create the block debugfs directory on init for these types of block devices: * request-based block driver block devices * every possible partition * scsi-generic And so, this race should in theory only be possible with make_request drivers. We can fix the UAF by simply re-using the debugfs directory for make_request drivers (multiqueue) and only creating the ephemeral directory for the other type of block devices. The new clarifications on relying on the q->blk_trace_mutex *and* also checking for q->blk_trace *prior* to processing a blktrace ensures the debugfs directories are only created if no possible directory name clashes are possible. This goes tested with: o nvme partitions o ISCSI with tgt, and blktracing against scsi-generic with: o block o tape o cdrom o media changer o blktests This patch is part of the work which disputes the severity of CVE-2019-19770 which shows this issue is not a core debugfs issue, but a misuse of debugfs within blktace. Fixes: 6ac93117ab00 ("blktrace: use existing disk debugfs directory") Reported-by: syzbot+603294af2d01acfdd6da@syzkaller.appspotmail.com Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Bart Van Assche <bvanassche@acm.org> Cc: Omar Sandoval <osandov@fb.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Nicolai Stange <nstange@suse.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: "James E.J. Bottomley" <jejb@linux.ibm.com> Cc: yu kuai <yukuai3@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-24blktrace: annotate required lock on do_blk_trace_setup()Luis Chamberlain1-0/+2
Ensure it is clear which lock is required on do_blk_trace_setup(). Suggested-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-17blktrace: Avoid sparse warnings when assigning q->blk_traceJan Kara1-11/+8
Mostly for historical reasons, q->blk_trace is assigned through xchg() and cmpxchg() atomic operations. Although this is correct, sparse complains about this because it violates rcu annotations since commit c780e86dd48e ("blktrace: Protect q->blk_trace with RCU") which started to use rcu for accessing q->blk_trace. Furthermore there's no real need for atomic operations anymore since all changes to q->blk_trace happen under q->blk_trace_mutex and since it also makes more sense to check if q->blk_trace is set with the mutex held earlier. So let's just replace xchg() with rcu_replace_pointer() and cmpxchg() with explicit check and rcu_assign_pointer(). This makes the code more efficient and sparse happy. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-17blktrace: break out of blktrace setup on concurrent callsLuis Chamberlain1-0/+13
We use one blktrace per request_queue, that means one per the entire disk. So we cannot run one blktrace on say /dev/vda and then /dev/vda1, or just two calls on /dev/vda. We check for concurrent setup only at the very end of the blktrace setup though. If we try to run two concurrent blktraces on the same block device the second one will fail, and the first one seems to go on. However when one tries to kill the first one one will see things like this: The kernel will show these: ``` debugfs: File 'dropped' in directory 'nvme1n1' already present! debugfs: File 'msg' in directory 'nvme1n1' already present! debugfs: File 'trace0' in directory 'nvme1n1' already present! `` And userspace just sees this error message for the second call: ``` blktrace /dev/nvme1n1 BLKTRACESETUP(2) /dev/nvme1n1 failed: 5/Input/output error ``` The first userspace process #1 will also claim that the files were taken underneath their nose as well. The files are taken away form the first process given that when the second blktrace fails, it will follow up with a BLKTRACESTOP and BLKTRACETEARDOWN. This means that even if go-happy process #1 is waiting for blktrace data, we *have* been asked to take teardown the blktrace. This can easily be reproduced with break-blktrace [0] run_0005.sh test. Just break out early if we know we're already going to fail, this will prevent trying to create the files all over again, which we know still exist. [0] https://github.com/mcgrof/break-blktrace Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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