From: tip-bot for Peter Zijlstra <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: tglx@linutronix.de, peterz@infradead.org,
akpm@linux-foundation.org, hpa@zytor.com,
paulmck@linux.vnet.ibm.com, adobriyan@gmail.com,
mingo@kernel.org, torvalds@linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: [tip:locking/core] locking/barriers: Validate lockless_dereference() is used on a pointer type
Date: Wed, 8 Jun 2016 07:19:38 -0700 [thread overview]
Message-ID: <tip-331b6d8c7afc2e5b900b9dcd850c265e1ba8d8e7@git.kernel.org> (raw)
In-Reply-To: <20160522104827.GP3193@twins.programming.kicks-ass.net>
Commit-ID: 331b6d8c7afc2e5b900b9dcd850c265e1ba8d8e7
Gitweb: http://git.kernel.org/tip/331b6d8c7afc2e5b900b9dcd850c265e1ba8d8e7
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Sun, 22 May 2016 12:48:27 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 8 Jun 2016 14:22:47 +0200
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>
---
include/linux/compiler.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 793c082..06f27fd 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); \
})
next prev parent reply other threads:[~2016-06-08 14:20 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-21 20:14 [PATCH] seqlock: fix raw_read_seqcount_latch() Alexey Dobriyan
2016-05-22 10:48 ` Peter Zijlstra
2016-05-22 18:50 ` Alexey Dobriyan
2016-05-23 9:36 ` Peter Zijlstra
2016-05-25 19:57 ` Tejun Heo
2016-05-25 20:11 ` [PATCH] percpu: Revert ("percpu: Replace smp_read_barrier_depends() with lockless_dereference()") Tejun Heo
2016-06-03 10:58 ` [tip:locking/core] locking/barriers: Validate lockless_dereference() is used on a pointer type tip-bot for Peter Zijlstra
2016-06-06 21:31 ` Mateusz Guzik
2016-06-07 7:10 ` Peter Zijlstra
2016-06-08 14:19 ` tip-bot for Peter Zijlstra [this message]
2016-05-27 11:11 ` [PATCH] seqlock: fix raw_read_seqcount_latch() Peter Zijlstra
2016-06-03 10:46 ` [tip:locking/core] locking/seqcount: Re-fix raw_read_seqcount_latch() tip-bot for Peter Zijlstra
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