11 Jan, 2012
1 commit
-
We can place this in definitions that we expect the compiler to remove by
dead code elimination. If this assertion fails, we get a nice error
message at build time.The GCC function attribute error("message") was added in version 4.3, so
we define a new macro __linktime_error(message) to expand to this for
GCC-4.3 and later. This will give us an error diagnostic from the
compiler on the line that fails. For other compilers
__linktime_error(message) expands to nothing, and we have to be content
with a link time error, but at least we will still get a build error.BUILD_BUG() expands to the undefined function __build_bug_failed() and
will fail at link time if the compiler ever emits code for it. On GCC-4.3
and later, attribute((error())) is used so that the failure will be noted
at compile time instead.Signed-off-by: David Daney
Acked-by: David Rientjes
Cc: DM
Cc: Ralf Baechle
Acked-by: David Howells
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
20 Aug, 2010
1 commit
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This commit provides definitions for the __rcu annotation defined earlier.
This annotation permits sparse to check for correct use of RCU-protected
pointers. If a pointer that is annotated with __rcu is accessed
directly (as opposed to via rcu_dereference(), rcu_assign_pointer(),
or one of their variants), sparse can be made to complain. To enable
such complaints, use the new default-disabled CONFIG_SPARSE_RCU_POINTER
kernel configuration option. Please note that these sparse complaints are
intended to be a debugging aid, -not- a code-style-enforcement mechanism.There are special rcu_dereference_protected() and rcu_access_pointer()
accessors for use when RCU read-side protection is not required, for
example, when no other CPU has access to the data structure in question
or while the current CPU hold the update-side lock.This patch also updates a number of docbook comments that were showing
their age.Signed-off-by: Arnd Bergmann
Signed-off-by: Paul E. McKenney
Cc: Christopher Li
Reviewed-by: Josh Triplett
15 Jun, 2010
1 commit
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This commit defines an __rcu API, but provides only vacuous definitions
for it. This breaks dependencies among most of the subsequent patches,
allowing them to reach mainline asynchronously via whatever trees are
appropriate.Signed-off-by: Arnd Bergmann
Signed-off-by: Paul E. McKenney
Cc: Christopher Li
Cc: Josh Triplett
05 Jan, 2010
1 commit
-
Conflicts:
arch/powerpc/platforms/pseries/hvCall.S
include/linux/percpu.h
06 Dec, 2009
3 commits
-
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
include/linux/compiler-gcc4.h: Fix build bug - gcc-4.0.2 doesn't understand __builtin_object_size
x86/alternatives: No need for alternatives-asm.h to re-invent stuff already in asm.h
x86/alternatives: Check replacementlen t use the strict copy checks when branch profiling is in use
x86, 64-bit: Move K8 B step iret fixup to fault entry asm
x86: Generate cmpxchg build failures
x86: Add a Kconfig option to turn the copy_from_user warnings into errors
x86: Turn the copy_from_user check into an (optional) compile time warning
x86: Use __builtin_memset and __builtin_memcpy for memset/memcpy
x86: Use __builtin_object_size() to validate the buffer size for copy_from_user() -
…el/git/tip/linux-2.6-tip
* 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (40 commits)
tracing: Separate raw syscall from syscall tracer
ring-buffer-benchmark: Add parameters to set produce/consumer priorities
tracing, function tracer: Clean up strstrip() usage
ring-buffer benchmark: Run producer/consumer threads at nice +19
tracing: Remove the stale include/trace/power.h
tracing: Only print objcopy version warning once from recordmcount
tracing: Prevent build warning: 'ftrace_graph_buf' defined but not used
ring-buffer: Move access to commit_page up into function used
tracing: do not disable interrupts for trace_clock_local
ring-buffer: Add multiple iterations between benchmark timestamps
kprobes: Sanitize struct kretprobe_instance allocations
tracing: Fix to use __always_unused attribute
compiler: Introduce __always_unused
tracing: Exit with error if a weak function is used in recordmcount.pl
tracing: Move conditional into update_funcs() in recordmcount.pl
tracing: Add regex for weak functions in recordmcount.pl
tracing: Move mcount section search to front of loop in recordmcount.pl
tracing: Fix objcopy revision check in recordmcount.pl
tracing: Check absolute path of input file in recordmcount.pl
tracing: Correct the check for number of arguments in recordmcount.pl
... -
Starting with version 4.5, GCC has a new built-in function
__builtin_unreachable() that can be used in places like the kernel's
BUG() where inline assembly is used to transfer control flow. This
eliminated the need for an endless loop in these places.The patch adds a new macro 'unreachable()' that will expand to either
__builtin_unreachable() or an endless loop depending on the compiler
version.Change from v1: Simplify unreachable() for non-GCC 4.5 case.
Signed-off-by: David Daney
Acked-by: Ralf Baechle
Signed-off-by: Linus Torvalds
02 Nov, 2009
1 commit
-
I wrote some code which is used as compile-time checker, and the
code should be elided after compile.So I need to annotate the code as "always unused", compared to
"maybe unused".Signed-off-by: Li Zefan
Cc: Steven Rostedt
Cc: Frederic Weisbecker
Cc: Linus Torvalds
LKML-Reference:
Signed-off-by: Ingo Molnar
29 Oct, 2009
1 commit
-
We have to make __kernel "__attribute__((address_space(0)))" so we can
cast to it.tj: * put_cpu_var() update.
* Annotations added to dynamic allocator interface.
Signed-off-by: Rusty Russell
Cc: Al Viro
Signed-off-by: Tejun Heo
03 Oct, 2009
1 commit
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For automated testing it is useful to have the option to turn
the warnings on copy_from_user() etc checks into errors:In function ‘copy_from_user’,
inlined from ‘fd_copyin’ at drivers/block/floppy.c:3080,
inlined from ‘fd_ioctl’ at drivers/block/floppy.c:3503:
linux/arch/x86/include/asm/uaccess_32.h:213:
error: call to ‘copy_from_user_overflow’ declared with attribute error:
copy_from_user buffer size is not provably correctSigned-off-by: Arjan van de Ven
Cc: Linus Torvalds
Cc: Andrew Morton
LKML-Reference:
Signed-off-by: Ingo Molnar
01 Oct, 2009
1 commit
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A previous patch added the buffer size check to copy_from_user().
One of the things learned from analyzing the result of the previous
patch is that in general, gcc is really good at proving that the
code contains sufficient security checks to not need to do a
runtime check. But that for those cases where gcc could not prove
this, there was a relatively high percentage of real security
issues.This patch turns the case of "gcc cannot prove" into a compile time
warning, as long as a sufficiently new gcc is in use that supports
this. The objective is that these warnings will trigger developers
checking new cases out before a security hole enters a linux kernel
release.Signed-off-by: Arjan van de Ven
Cc: Linus Torvalds
Cc: "David S. Miller"
Cc: James Morris
Cc: Jan Beulich
LKML-Reference:
Signed-off-by: Ingo Molnar
26 Sep, 2009
1 commit
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gcc (4.x) supports the __builtin_object_size() builtin, which
reports the size of an object that a pointer point to, when known
at compile time. If the buffer size is not known at compile time, a
constant -1 is returned.This patch uses this feature to add a sanity check to
copy_from_user(); if the target buffer is known to be smaller than
the copy size, the copy is aborted and a WARNing is emitted in
memory debug mode.These extra checks compile away when the object size is not known,
or if both the buffer size and the copy length are constants.Signed-off-by: Arjan van de Ven
LKML-Reference:
Signed-off-by: Ingo Molnar
12 Jun, 2009
1 commit
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Impact: new API
__builtin_types_compatible_p() is a little awkward to use: it takes two
types rather than types or variables, and it's just damn long.(typeof(type) == type, so this works on types as well as vars).
Signed-off-by: Rusty Russell
07 Apr, 2009
2 commits
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Fix the branch tracer barfing on comma statements within if ()
statements.Signed-off-by: Ingo Molnar
-
One of the changes between kernels 2.6.28 and 2.6.29 is that a branch profiler
has been added for if() statements. Unfortunately this patch makes the sparse
output unusable with CONFIG_TRACE_BRANCH_PROFILING=y: when branch profiling is
enabled, sparse prints so much false positives that the real issues are no
longer visible. This behavior can be reproduced as follows:
* enable CONFIG_TRACE_BRANCH_PROFILING, e.g. by running make allyesconfig or
make allmodconfig.
* run make C=2Result: a huge number of the following sparse warnings.
...
include/linux/cpumask.h:547:2: warning: symbol '______r' shadows an earlier one
include/linux/cpumask.h:547:2: originally declared here
...The patch below fixes this by disabling branch profiling while analyzing the
kernel code with sparse.See also:
* http://lkml.org/lkml/2008/11/21/18
* http://bugzilla.kernel.org/show_bug.cgi?id=12925Signed-off-by: Bart Van Assche
Cc: Andrew Morton
Cc: Steven Rostedt
LKML-Reference:
Signed-off-by: Ingo Molnar
18 Mar, 2009
1 commit
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Impact: better performance for if branch tracer
Use an array to count the hit and misses of a conditional instead
of using another conditional. This cuts down on saturation of branch
predictions and increases performance of modern pipelined architectures.Signed-off-by: Witold Baryluk
Signed-off-by: Steven Rostedt
03 Jan, 2009
1 commit
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- include the gcc version-dependent header files from the generic gcc
header file, rather than the other way around (iow: don't make the
non-gcc header file have to know about gcc versions)- don't include compiler-gcc4.h for gcc 5 (for whenever it gets
released). That's just confusing and made us do odd things in the
gcc4 header file (testing that we really had version 4!)- generate the name from the __GNUC__ version directly, rather than
having a mess of #if conditionals.Signed-off-by: Linus Torvalds
23 Nov, 2008
3 commits
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Impact: feature to profile if statements
This patch adds a branch profiler for all if () statements.
The results will be found in:/debugfs/tracing/profile_branch
For example:
miss hit % Function File Line
------- --------- - -------- ---- ----
0 1 100 x86_64_start_reservations head64.c 127
0 1 100 copy_bootdata head64.c 69
1 0 0 x86_64_start_kernel head64.c 111
32 0 0 set_intr_gate desc.h 319
1 0 0 reserve_ebda_region head.c 51
1 0 0 reserve_ebda_region head.c 47
0 1 100 reserve_ebda_region head.c 42
0 0 X maxcpus main.c 165Miss means the branch was not taken. Hit means the branch was taken.
The percent is the percentage the branch was taken.This adds a significant amount of overhead and should only be used
by those analyzing their system.Signed-off-by: Steven Rostedt
Signed-off-by: Ingo Molnar -
Impact: clean up to make one profiler of like and unlikely tracer
The likely and unlikely profiler prints out the file and line numbers
of the annotated branches that it is profiling. It shows the number
of times it was correct or incorrect in its guess. Having two
different files or sections for that matter to tell us if it was a
likely or unlikely is pretty pointless. We really only care if
it was correct or not.Signed-off-by: Steven Rostedt
Signed-off-by: Ingo Molnar -
Impact: clean up of branch check
The unlikely/likely profiler does an extra assign of the f.line.
This is not needed since it is already calculated at compile time.Signed-off-by: Steven Rostedt
Signed-off-by: Ingo Molnar
13 Nov, 2008
1 commit
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Impact: name change of unlikely tracer and profiler
Ingo Molnar suggested changing the config from UNLIKELY_PROFILE
to BRANCH_PROFILING. I never did like the "unlikely" name so I
went one step farther, and renamed all the unlikely configurations
to a "BRANCH" variant.Signed-off-by: Steven Rostedt
Signed-off-by: Ingo Molnar
12 Nov, 2008
2 commits
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Impact: fix bootup crash
the branch tracer missed arch/x86/vdso/vclock_gettime.c from
disabling tracing, which caused such bootup crashes:[ 201.840097] init[1]: segfault at 7fffed3fe7c0 ip 00007fffed3fea2e sp 000077
also clean up the ugly ifdefs in arch/x86/kernel/vsyscall_64.c by
creating DISABLE_UNLIKELY_PROFILE facility for code to turn off
instrumentation on a per file basis.Signed-off-by: Ingo Molnar
-
Impact: new unlikely/likely profiler
Andrew Morton recently suggested having an in-kernel way to profile
likely and unlikely macros. This patch achieves that goal.When configured, every(*) likely and unlikely macro gets a counter attached
to it. When the condition is hit, the hit and misses of that condition
are recorded. These numbers can later be retrieved by:/debugfs/tracing/profile_likely - All likely markers
/debugfs/tracing/profile_unlikely - All unlikely markers.# cat /debug/tracing/profile_unlikely | head
correct incorrect % Function File Line
------- --------- - -------- ---- ----
2167 0 0 do_arch_prctl process_64.c 832
0 0 0 do_arch_prctl process_64.c 804
2670 0 0 IS_ERR err.h 34
71230 5693 7 __switch_to process_64.c 673
76919 0 0 __switch_to process_64.c 639
43184 33743 43 __switch_to process_64.c 624
12740 64181 83 __switch_to process_64.c 594
12740 64174 83 __switch_to process_64.c 590# cat /debug/tracing/profile_unlikely | \
awk '{ if ($3 > 25) print $0; }' |head -20
44963 35259 43 __switch_to process_64.c 624
12762 67454 84 __switch_to process_64.c 594
12762 67447 84 __switch_to process_64.c 590
1478 595 28 syscall_get_error syscall.h 51
0 2821 100 syscall_trace_leave ptrace.c 1567
0 1 100 native_smp_prepare_cpus smpboot.c 1237
86338 265881 75 calc_delta_fair sched_fair.c 408
210410 108540 34 calc_delta_mine sched.c 1267
0 54550 100 sched_info_queued sched_stats.h 222
51899 66435 56 pick_next_task_fair sched_fair.c 1422
6 10 62 yield_task_fair sched_fair.c 982
7325 2692 26 rt_policy sched.c 144
0 1270 100 pre_schedule_rt sched_rt.c 1261
1268 48073 97 pick_next_task_rt sched_rt.c 884
0 45181 100 sched_info_dequeued sched_stats.h 177
0 15 100 sched_move_task sched.c 8700
0 15 100 sched_move_task sched.c 8690
53167 33217 38 schedule sched.c 4457
0 80208 100 sched_info_switch sched_stats.h 270
30585 49631 61 context_switch sched.c 2619# cat /debug/tracing/profile_likely | awk '{ if ($3 > 25) print $0; }'
39900 36577 47 pick_next_task sched.c 4397
20824 15233 42 switch_mm mmu_context_64.h 18
0 7 100 __cancel_work_timer workqueue.c 560
617 66484 99 clocksource_adjust timekeeping.c 456
0 346340 100 audit_syscall_exit auditsc.c 1570
38 347350 99 audit_get_context auditsc.c 732
0 345244 100 audit_syscall_entry auditsc.c 1541
38 1017 96 audit_free auditsc.c 1446
0 1090 100 audit_alloc auditsc.c 862
2618 1090 29 audit_alloc auditsc.c 858
0 6 100 move_masked_irq migration.c 9
1 198 99 probe_sched_wakeup trace_sched_switch.c 58
2 2 50 probe_wakeup trace_sched_wakeup.c 227
0 2 100 probe_wakeup_sched_switch trace_sched_wakeup.c 144
4514 2090 31 __grab_cache_page filemap.c 2149
12882 228786 94 mapping_unevictable pagemap.h 50
4 11 73 __flush_cpu_slab slub.c 1466
627757 330451 34 slab_free slub.c 1731
2959 61245 95 dentry_lru_del_init dcache.c 153
946 1217 56 load_elf_binary binfmt_elf.c 904
102 82 44 disk_put_part genhd.h 206
1 1 50 dst_gc_task dst.c 82
0 19 100 tcp_mss_split_point tcp_output.c 1126As you can see by the above, there's a bit of work to do in rethinking
the use of some unlikelys and likelys. Note: the unlikely case had 71 hits
that were more than 25%.Note: After submitting my first version of this patch, Andrew Morton
showed me a version written by Daniel Walker, where I picked up
the following ideas from:1) Using __builtin_constant_p to avoid profiling fixed values.
2) Using __FILE__ instead of instruction pointers.
3) Using the preprocessor to stop all profiling of likely
annotations from vsyscall_64.c.Thanks to Andrew Morton, Arjan van de Ven, Theodore Tso and Ingo Molnar
for their feed back on this patch.(*) Not ever unlikely is recorded, those that are used by vsyscalls
(a few of them) had to have profiling disabled.Signed-off-by: Steven Rostedt
Cc: Andrew Morton
Cc: Frederic Weisbecker
Cc: Theodore Tso
Cc: Arjan van de Ven
Cc: Steven Rostedt
Signed-off-by: Ingo Molnar
14 Oct, 2008
1 commit
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The notrace define belongs in compiler.h so that it can be used in
init.hSigned-off-by: Steven Rostedt
Signed-off-by: Ingo Molnar
18 Aug, 2008
1 commit
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Remove the redundant definition of ACCESS_ONCE() from rcupreempt.c in
favor of the one in compiler.h. Also merge the comment header from
rcupreempt.c's definition into that in compiler.h.Signed-off-by: Paul E. McKenney
Signed-off-by: Ingo Molnar
11 May, 2008
1 commit
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It actually makes much more sense there, and we do tend to need it for
non-RCU usage too. Moving it to will allow some
other cases that have open-coded the same logic to use the same helper
function that RCU has used.Signed-off-by: Linus Torvalds
05 Mar, 2008
1 commit
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People are adding `noinline' in various places to prevent excess stack
consumption due to gcc inlining. But once this is done, it is quite unobvious
why the `noinline' is present in the code. We can comment each and every
site, or we can use noinline_for_stack.Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
29 Jan, 2008
2 commits
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Remove the deprecated __attribute_used__.
[Introduce __section in a few places to silence checkpatch /sam]
Signed-off-by: Adrian Bunk
Signed-off-by: Sam Ravnborg -
Add a new helper: __section() that makes a section definition
much shorter and more readable.Signed-off-by: Sam Ravnborg
26 Oct, 2007
1 commit
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The __deprecated marker is quite useful in highlighting the remnants of
old APIs that want removing.However, it is quite normal for one or more years to pass, before the
(usually ancient, bitrotten) code in question is either updated or
deleted.Thus, like __must_check, add a Kconfig option that permits the silencing
of this compiler warning.This change mimics the ifdef-ery and Kconfig defaults of MUST_CHECK as
closely as possible.Signed-off-by: Jeff Garzik
Signed-off-by: Linus Torvalds
19 Oct, 2007
1 commit
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To be consistent with the use of attributes in the rest of the kernel
replace all use of __attribute_pure__ with __pure and delete the definition
of __attribute_pure__.Signed-off-by: Ralf Baechle
Cc: Russell King
Acked-by: Mauro Carvalho Chehab
Cc: Bryan Wu
Cc: Paul Mackerras
Cc: Benjamin Herrenschmidt
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
27 Jul, 2007
1 commit
-
Signed-off-by: Al Viro
Signed-off-by: Linus Torvalds
22 Jul, 2007
1 commit
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gcc 4.3 supports a new __attribute__((__cold__)) to mark functions cold. Any
path directly leading to a call of this function will be unlikely. And gcc
will try to generate smaller code for the function itself.Please use with care. The code generation advantage isn't large and in most
cases it is not worth uglifying code with this.This patch marks some common error functions like panic(), printk()
as cold. This will longer term make many unlikely()s unnecessary, although
we can keep them for now for older compilers.BUG is not marked cold because there is currently no way to tell
gcc to mark a inline function told.Also all __init and __exit functions are marked cold. With a non -Os
build this will tell the compiler to generate slightly smaller code
for them. I think it currently only uses less alignments for labels,
but that might change in the future.One disadvantage over *likely() is that they cannot be easily instrumented
to verify them.Another drawback is that only the latest gcc 4.3 snapshots support this.
Unfortunately we cannot detect this using the preprocessor. This means older
snapshots will fail now. I don't think that's a problem because they are
unreleased compilers that nobody should be using.gcc also has a __hot__ attribute, but I don't see any sense in using
this in the kernel right now. But someday I hope gcc will be able
to use more aggressive optimizing for hot functions even in -Os,
if that happens it should be added.Includes compile fix from Thomas Gleixner.
Cc: Jan Hubicka
Signed-off-by: Andi Kleen
Signed-off-by: Linus Torvalds
22 May, 2007
1 commit
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The ifdef tests were broken. Assume it acts like gcc 4
Signed-off-by: Andi Kleen
Signed-off-by: Linus Torvalds
10 May, 2007
1 commit
-
__used is defined to be __attribute__((unused)) for all pre-3.3 gcc
compilers to suppress warnings for unused functions because perhaps they
are referenced only in inline assembly. It is defined to be
__attribute__((used)) for gcc 3.3 and later so that the code is still
emitted for such functions.__maybe_unused is defined to be __attribute__((unused)) for both function
and variable use if it could possibly be unreferenced due to the evaluation
of preprocessor macros. Function prototypes shall be marked with
__maybe_unused if the actual definition of the function is dependant on
preprocessor macros.No update to compiler-intel.h is necessary because ICC supports both
__attribute__((used)) and __attribute__((unused)) as specified by the gcc
manual.__attribute_used__ is deprecated and will be removed once all current
code is converted to using __used.Cc: Rusty Russell
Cc: Adrian Bunk
Signed-off-by: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
27 Mar, 2007
1 commit
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Change prototypes for __chk_user_ptr and __chk_io_ptr to take const
void* instead of void*, so that code can pass "const void *" to them.(Right now sparse does not warn about passing const void* to void*
functions, but that is a separate bug that I believe Josh is working on,
and once sparse does check this, the changed prototypes will be
necessary.)Signed-off-by: Russ Cox
Signed-off-by: Josh Triplett
Acked-by: Christopher Li
Signed-off-by: Linus Torvalds
13 Dec, 2006
1 commit
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The kernel doesn't compile with GCC
Signed-off-by: Adrian Bunk
01 Oct, 2006
1 commit
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The lock annotation macros __acquires, __releases, __acquire, and __release
all currently throw away the lock expression passed as an argument. Now
that sparse can parse __context__ and __attribute__((context)) with a
context expression, pass the lock expression down to sparse as the context
expression. This requires a version of sparse from GIT commit
37475a6c1c3e66219e68d912d5eb833f4098fd72 or later.Signed-off-by: Josh Triplett
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
30 Sep, 2006
1 commit
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Currently, __acquire and __release take a lock expression, but __cond_lock
takes only a condition, not the lock acquired if the expression evaluates
to true. Change __cond_lock to accept a lock expression, and change all
the callers to pass in a lock expression.Signed-off-by: Josh Triplett
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
26 Sep, 2006
1 commit
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Those 1500 warnings can be a bit of a pain. Add a config option to shut them
up.Signed-off-by: Andrew Morton
Signed-off-by: Greg Kroah-Hartman
