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| author | Peter Zijlstra <peterz@infradead.org> | 2016-05-22 12:48:27 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-06-08 14:22:47 +0200 |
| commit | 331b6d8c7afc2e5b900b9dcd850c265e1ba8d8e7 (patch) | |
| tree | cf3060a9a96357e5f321e5ed28a5165717674f0d | |
| parent | locking/rtmutex: Only warn once on a trylock from bad context (diff) | |
| download | linux-331b6d8c7afc2e5b900b9dcd850c265e1ba8d8e7.tar.xz linux-331b6d8c7afc2e5b900b9dcd850c265e1ba8d8e7.zip | |
locking/barriers: Validate lockless_dereference() is used on a pointer type
Use the type to validate the argument @p is indeed a pointer type.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160522104827.GP3193@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | include/linux/compiler.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 793c0829e3a3..06f27fd9d760 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -545,10 +545,14 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s * Similar to rcu_dereference(), but for situations where the pointed-to * object's lifetime is managed by something other than RCU. That * "something other" might be reference counting or simple immortality. + * + * The seemingly unused void * variable is to validate @p is indeed a pointer + * type. All pointer types silently cast to void *. */ #define lockless_dereference(p) \ ({ \ typeof(p) _________p1 = READ_ONCE(p); \ + __maybe_unused const void * const _________p2 = _________p1; \ smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ (_________p1); \ }) |