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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2016-05-01 18:46:54 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2016-06-15 15:31:28 -0700 |
| commit | 3a37f7275cda5ad25c1fe9be8f20c76c60d175fa (patch) | |
| tree | 89e64cf1b726c48daf24663dd15be033589c7dba | |
| parent | 810ce8b5df1c8338065f2ae1d2ec08cc566fbb8b (diff) | |
| download | op-kernel-dev-3a37f7275cda5ad25c1fe9be8f20c76c60d175fa.zip op-kernel-dev-3a37f7275cda5ad25c1fe9be8f20c76c60d175fa.tar.gz | |
rcu: No ordering for rcu_assign_pointer() of NULL
This commit does a compile-time check for rcu_assign_pointer() of NULL,
and uses WRITE_ONCE() rather than smp_store_release() in that case.
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| -rw-r--r-- | include/linux/rcupdate.h | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index c61b6b9..a8af797 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -650,7 +650,16 @@ static inline void rcu_preempt_sleep_check(void) * please be careful when making changes to rcu_assign_pointer() and the * other macros that it invokes. */ -#define rcu_assign_pointer(p, v) smp_store_release(&p, RCU_INITIALIZER(v)) +#define rcu_assign_pointer(p, v) \ +({ \ + uintptr_t _r_a_p__v = (uintptr_t)(v); \ + \ + if (__builtin_constant_p(v) && (_r_a_p__v) == (uintptr_t)NULL) \ + WRITE_ONCE((p), (typeof(p))(_r_a_p__v)); \ + else \ + smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \ + _r_a_p__v; \ +}) /** * rcu_access_pointer() - fetch RCU pointer with no dereferencing |
