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| author |   Johannes Thumshirn <jthumshirn@suse.de> | 2018-05-17 13:52:50 +0200 |
|---|---|---|
| committer |   Keith Busch <keith.busch@intel.com> | 2018-05-23 08:58:27 -0600 |
| commit | 978628ec795b18179e74ef12cfcd35bae569d13e (patch) | |
| tree | 3ed0f150c086817e072083703cdb6f23011d8ce2 | |
| parent | blkdev_report_zones_ioctl(): Use vmalloc() to allocate large buffers (diff) | |
| download | linux-dev-978628ec795b18179e74ef12cfcd35bae569d13e.tar.xz linux-dev-978628ec795b18179e74ef12cfcd35bae569d13e.zip | |
nvme: fix lockdep warning in nvme_mpath_clear_current_path
When running blktest's nvme/005 with a lockdep enabled kernel the test
case fails due to the following lockdep splat in dmesg:
=============================
WARNING: suspicious RCU usage
4.17.0-rc5 #881 Not tainted
-----------------------------
drivers/nvme/host/nvme.h:457 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
3 locks held by kworker/u32:5/1102:
#0: (ptrval) ((wq_completion)"nvme-wq"){+.+.}, at: process_one_work+0x152/0x5c0
#1: (ptrval) ((work_completion)(&ctrl->scan_work)){+.+.}, at: process_one_work+0x152/0x5c0
#2: (ptrval) (&subsys->lock#2){+.+.}, at: nvme_ns_remove+0x43/0x1c0 [nvme_core]
The only caller of nvme_mpath_clear_current_path() is nvme_ns_remove()
which holds the subsys lock so it's likely a false positive, but when
using rcu_access_pointer(), we're telling rcu and lockdep that we're
only after the pointer falue.
Fixes: 32acab3181c7 ("nvme: implement multipath access to nvme subsystems")
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Suggested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
| -rw-r--r-- | drivers/nvme/host/nvme.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index 35d9915829e2..ec6e4acc4d48 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -22,6 +22,7 @@ #include <linux/lightnvm.h> #include <linux/sed-opal.h> #include <linux/fault-inject.h> +#include <linux/rcupdate.h> extern unsigned int nvme_io_timeout; #define NVME_IO_TIMEOUT (nvme_io_timeout * HZ) @@ -449,7 +450,7 @@ static inline void nvme_mpath_clear_current_path(struct nvme_ns *ns) { struct nvme_ns_head *head = ns->head; - if (head && ns == srcu_dereference(head->current_path, &head->srcu)) + if (head && ns == rcu_access_pointer(head->current_path)) rcu_assign_pointer(head->current_path, NULL); } struct nvme_ns *nvme_find_path(struct nvme_ns_head *head); |