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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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ConfigItem executes parent->takeChild(0)
while
ConfigList executes parent->takeTopLevelItem(0)
Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Recursive dependency issues with kconfig are unavoidable due to
some limitations with kconfig, since these issues are recurring
provide a hint to the user how they can resolve these dependency
issues and also document why such limitation exists.
While at it also document a bit of future prospects of ways to
enhance Kconfig, including providing formal semantics and evaluation
of use of a SAT solver. If you're interested in this work or prospects
of it check out the kconfig-sat project wiki [0] and mailing list [1].
[0] http://kernelnewbies.org/KernelProjects/kconfig-sat
[1] https://groups.google.com/d/forum/kconfig-sat
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: James Bottomley <jbottomley@odin.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mate Soos <soos.mate@gmail.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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rq_data_dir() returns either READ or WRITE (0 == READ, 1 == WRITE), not
a boolean value.
Now, admittedly the "!= 0" doesn't really change the value (0 stays as
zero, 1 stays as one), but it's not only redundant, it confuses gcc, and
causes gcc to warn about the construct
switch (rq_data_dir(req)) {
case READ:
...
case WRITE:
...
that we have in a few drivers.
Now, the gcc warning is silly and stupid (it seems to warn not about the
switch value having a different type from the case statements, but about
_any_ boolean switch value), but in this case the code itself is silly
and stupid too, so let's just change it, and get rid of warnings like
this:
drivers/block/hd.c: In function ‘hd_request’:
drivers/block/hd.c:630:11: warning: switch condition has boolean value [-Wswitch-bool]
switch (rq_data_dir(req)) {
The odd '!= 0' came in when "cmd_flags" got turned into a "u64" in
commit 5953316dbf90 ("block: make rq->cmd_flags be 64-bit") and is
presumably because the old code (that just did a logical 'and' with 1)
would then end up making the type of rq_data_dir() be u64 too.
But if we want to retain the old regular integer type, let's just cast
the result to 'int' rather than use that rather odd '!= 0'.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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We had to revert the pluggin in writeback_sb_inodes() because the
wb->list_lock is held, but we could easily plug at a higher level before
taking that lock, and unplug after releasing it. This does that.
Chris will run performance numbers, just to verify that this approach is
comparable to the alternative (we could just drop and re-take the lock
around the blk_finish_plug() rather than these two commits.
I'd have preferred waiting for actual performance numbers before picking
one approach over the other, but I don't want to release rc1 with the
known "sleeping function called from invalid context" issue, so I'll
pick this cleanup version for now. But if the numbers show that we
really want to plug just at the writeback_sb_inodes() level, and we
should just play ugly games with the spinlock, we'll switch to that.
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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I didn't notice this when merging the thermal code from Zhang, but his
merge (commit 5a924a07f882: "Merge branches 'thermal-core' and
'thermal-intel' of .git into next") of the thermal-core and
thermal-intel branches was wrong.
In thermal-core, commit 17e8351a7739 ("thermal: consistently use int for
temperatures") converted the thermal layer to use "int" for
temperatures.
But in parallel, in the thermal-intel branch commit d0a12625d2ff
("thermal: Add Intel PCH thermal driver") added support for the intel
PCH thermal sensor using the old interfaces that used "unsigned long"
pointers.
This resulted in warnings like this:
drivers/thermal/intel_pch_thermal.c:184:14: warning: initialization from incompatible pointer type [-Wincompatible-pointer-types]
.get_temp = pch_thermal_get_temp,
^
drivers/thermal/intel_pch_thermal.c:184:14: note: (near initialization for ‘tzd_ops.get_temp’)
drivers/thermal/intel_pch_thermal.c:186:19: warning: initialization from incompatible pointer type [-Wincompatible-pointer-types]
.get_trip_temp = pch_get_trip_temp,
^
drivers/thermal/intel_pch_thermal.c:186:19: note: (near initialization for ‘tzd_ops.get_trip_temp’)
This fixes it.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Newer bitfiles needs the reduced clk even for SMP builds
Cc: <stable@vger.kernel.org> #4.2
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Revert commit f83c7b5e9fd6 ("ocfs2/dlm: use list_for_each_entry instead
of list_for_each").
list_for_each_entry() will dereference its `pos' argument, which can be
NULL in dlm_process_recovery_data().
Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Reported-by: Fengguang Wu <fengguang.wu@gmail.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Commit 6b0f68e32ea8 ("mm: add utility for early copy from unmapped ram")
introduces a function copy_from_early_mem() into mm/early_ioremap.c
which itself calls early_memremap()/early_memunmap(). However, since
early_memunmap() has not been declared yet at this point in the .c file,
nor by any explicitly included header files, we are depending on a
transitive include of asm/early_ioremap.h to declare it, which is
fragile.
So instead, include this header explicitly.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The seq_<foo> function return values were frequently misused.
See: commit 1f33c41c03da ("seq_file: Rename seq_overflow() to
seq_has_overflowed() and make public")
All uses of these return values have been removed, so convert the
return types to void.
Miscellanea:
o Move seq_put_decimal_<type> and seq_escape prototypes closer the
other seq_vprintf prototypes
o Reorder seq_putc and seq_puts to return early on overflow
o Add argument names to seq_vprintf and seq_printf
o Update the seq_escape kernel-doc
o Convert a couple of leading spaces to tabs in seq_escape
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Update the membarrier syscall self-test to match the membarrier
interface. Extend coverage of the interface. Consider ENOSYS as a
"SKIP" test, since it is a valid configuration, but does not allow
testing the system call.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Pranith Kumar <bobby.prani@gmail.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Add a self test for the membarrier system call.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Here is an implementation of a new system call, sys_membarrier(), which
executes a memory barrier on all threads running on the system. It is
implemented by calling synchronize_sched(). It can be used to
distribute the cost of user-space memory barriers asymmetrically by
transforming pairs of memory barriers into pairs consisting of
sys_membarrier() and a compiler barrier. For synchronization primitives
that distinguish between read-side and write-side (e.g. userspace RCU
[1], rwlocks), the read-side can be accelerated significantly by moving
the bulk of the memory barrier overhead to the write-side.
The existing applications of which I am aware that would be improved by
this system call are as follows:
* Through Userspace RCU library (http://urcu.so)
- DNS server (Knot DNS) https://www.knot-dns.cz/
- Network sniffer (http://netsniff-ng.org/)
- Distributed object storage (https://sheepdog.github.io/sheepdog/)
- User-space tracing (http://lttng.org)
- Network storage system (https://www.gluster.org/)
- Virtual routers (https://events.linuxfoundation.org/sites/events/files/slides/DPDK_RCU_0MQ.pdf)
- Financial software (https://lkml.org/lkml/2015/3/23/189)
Those projects use RCU in userspace to increase read-side speed and
scalability compared to locking. Especially in the case of RCU used by
libraries, sys_membarrier can speed up the read-side by moving the bulk of
the memory barrier cost to synchronize_rcu().
* Direct users of sys_membarrier
- core dotnet garbage collector (https://github.com/dotnet/coreclr/issues/198)
Microsoft core dotnet GC developers are planning to use the mprotect()
side-effect of issuing memory barriers through IPIs as a way to implement
Windows FlushProcessWriteBuffers() on Linux. They are referring to
sys_membarrier in their github thread, specifically stating that
sys_membarrier() is what they are looking for.
To explain the benefit of this scheme, let's introduce two example threads:
Thread A (non-frequent, e.g. executing liburcu synchronize_rcu())
Thread B (frequent, e.g. executing liburcu
rcu_read_lock()/rcu_read_unlock())
In a scheme where all smp_mb() in thread A are ordering memory accesses
with respect to smp_mb() present in Thread B, we can change each
smp_mb() within Thread A into calls to sys_membarrier() and each
smp_mb() within Thread B into compiler barriers "barrier()".
Before the change, we had, for each smp_mb() pairs:
Thread A Thread B
previous mem accesses previous mem accesses
smp_mb() smp_mb()
following mem accesses following mem accesses
After the change, these pairs become:
Thread A Thread B
prev mem accesses prev mem accesses
sys_membarrier() barrier()
follow mem accesses follow mem accesses
As we can see, there are two possible scenarios: either Thread B memory
accesses do not happen concurrently with Thread A accesses (1), or they
do (2).
1) Non-concurrent Thread A vs Thread B accesses:
Thread A Thread B
prev mem accesses
sys_membarrier()
follow mem accesses
prev mem accesses
barrier()
follow mem accesses
In this case, thread B accesses will be weakly ordered. This is OK,
because at that point, thread A is not particularly interested in
ordering them with respect to its own accesses.
2) Concurrent Thread A vs Thread B accesses
Thread A Thread B
prev mem accesses prev mem accesses
sys_membarrier() barrier()
follow mem accesses follow mem accesses
In this case, thread B accesses, which are ensured to be in program
order thanks to the compiler barrier, will be "upgraded" to full
smp_mb() by synchronize_sched().
* Benchmarks
On Intel Xeon E5405 (8 cores)
(one thread is calling sys_membarrier, the other 7 threads are busy
looping)
1000 non-expedited sys_membarrier calls in 33s =3D 33 milliseconds/call.
* User-space user of this system call: Userspace RCU library
Both the signal-based and the sys_membarrier userspace RCU schemes
permit us to remove the memory barrier from the userspace RCU
rcu_read_lock() and rcu_read_unlock() primitives, thus significantly
accelerating them. These memory barriers are replaced by compiler
barriers on the read-side, and all matching memory barriers on the
write-side are turned into an invocation of a memory barrier on all
active threads in the process. By letting the kernel perform this
synchronization rather than dumbly sending a signal to every process
threads (as we currently do), we diminish the number of unnecessary wake
ups and only issue the memory barriers on active threads. Non-running
threads do not need to execute such barrier anyway, because these are
implied by the scheduler context switches.
Results in liburcu:
Operations in 10s, 6 readers, 2 writers:
memory barriers in reader: 1701557485 reads, 2202847 writes
signal-based scheme: 9830061167 reads, 6700 writes
sys_membarrier: 9952759104 reads, 425 writes
sys_membarrier (dyn. check): 7970328887 reads, 425 writes
The dynamic sys_membarrier availability check adds some overhead to
the read-side compared to the signal-based scheme, but besides that,
sys_membarrier slightly outperforms the signal-based scheme. However,
this non-expedited sys_membarrier implementation has a much slower grace
period than signal and memory barrier schemes.
Besides diminishing the number of wake-ups, one major advantage of the
membarrier system call over the signal-based scheme is that it does not
need to reserve a signal. This plays much more nicely with libraries,
and with processes injected into for tracing purposes, for which we
cannot expect that signals will be unused by the application.
An expedited version of this system call can be added later on to speed
up the grace period. Its implementation will likely depend on reading
the cpu_curr()->mm without holding each CPU's rq lock.
This patch adds the system call to x86 and to asm-generic.
[1] http://urcu.so
membarrier(2) man page:
MEMBARRIER(2) Linux Programmer's Manual MEMBARRIER(2)
NAME
membarrier - issue memory barriers on a set of threads
SYNOPSIS
#include <linux/membarrier.h>
int membarrier(int cmd, int flags);
DESCRIPTION
The cmd argument is one of the following:
MEMBARRIER_CMD_QUERY
Query the set of supported commands. It returns a bitmask of
supported commands.
MEMBARRIER_CMD_SHARED
Execute a memory barrier on all threads running on the system.
Upon return from system call, the caller thread is ensured that
all running threads have passed through a state where all memory
accesses to user-space addresses match program order between
entry to and return from the system call (non-running threads
are de facto in such a state). This covers threads from all pro=E2=80=90
cesses running on the system. This command returns 0.
The flags argument needs to be 0. For future extensions.
All memory accesses performed in program order from each targeted
thread is guaranteed to be ordered with respect to sys_membarrier(). If
we use the semantic "barrier()" to represent a compiler barrier forcing
memory accesses to be performed in program order across the barrier,
and smp_mb() to represent explicit memory barriers forcing full memory
ordering across the barrier, we have the following ordering table for
each pair of barrier(), sys_membarrier() and smp_mb():
The pair ordering is detailed as (O: ordered, X: not ordered):
barrier() smp_mb() sys_membarrier()
barrier() X X O
smp_mb() X O O
sys_membarrier() O O O
RETURN VALUE
On success, these system calls return zero. On error, -1 is returned,
and errno is set appropriately. For a given command, with flags
argument set to 0, this system call is guaranteed to always return the
same value until reboot.
ERRORS
ENOSYS System call is not implemented.
EINVAL Invalid arguments.
Linux 2015-04-15 MEMBARRIER(2)
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Miell <nmiell@comcast.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Pranith Kumar <bobby.prani@gmail.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix the following warning when compiling extract-cert:
scripts/extract-cert.c: In function `write_cert':
scripts/extract-cert.c:89:2: warning: format not a string literal and no format arguments [-Wformat-security]
ERR(!i2d_X509_bio(wb, x509), cert_dst);
^
whereby the ERR() macro is taking cert_dst as the format string. "%s"
should be used as the format string as the path could contain special
characters.
Signed-off-by: David Howells <dhowells@redhat.com>
Reported-by: Jim Davis <jim.epost@gmail.com>
Acked-by : David Woodhouse <david.woodhouse@intel.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This reverts commit d353d7587d02116b9732d5c06615aed75a4d3a47.
Doing the block layer plug/unplug inside writeback_sb_inodes() is
broken, because that function is actually called with a spinlock held:
wb->list_lock, as pointed out by Chris Mason.
Chris suggested just dropping and re-taking the spinlock around the
blk_finish_plug() call (the plgging itself can happen under the
spinlock), and that would technically work, but is just disgusting.
We do something fairly similar - but not quite as disgusting because we
at least have a better reason for it - in writeback_single_inode(), so
it's not like the caller can depend on the lock being held over the
call, but in this case there just isn't any good reason for that
"release and re-take the lock" pattern.
[ In general, we should really strive to avoid the "release and retake"
pattern for locks, because in the general case it can easily cause
subtle bugs when the caller caches any state around the call that
might be invalidated by dropping the lock even just temporarily. ]
But in this case, the plugging should be easy to just move up to the
callers before the spinlock is taken, which should even improve the
effectiveness of the plug. So there is really no good reason to play
games with locking here.
I'll send off a test-patch so that Dave Chinner can verify that that
plug movement works. In the meantime this just reverts the problematic
commit and adds a comment to the function so that we hopefully don't
make this mistake again.
Reported-by: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Boris Barbulovski
Luis R. Rodriguez
Linus Torvalds
Vineet Gupta
Andrew Morton
Ard Biesheuvel
Joe Perches
Mathieu Desnoyers
Pranith Kumar
David Howells