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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-09-18 17:45:22 +0200
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-10-06 20:16:42 +0200
commit7f5f873c6a0772970d5fee1f364231207051ecd8 (patch)
treeca06a26b0a485a63cf42417a12dea443a0df103c /kernel/rcu/tree.c
parentrcu: Remove deprecated rcu_lockdep_assert() (diff)
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rculist: Use WRITE_ONCE() when deleting from reader-visible list
The various RCU list-deletion macros (list_del_rcu(), hlist_del_init_rcu(), hlist_del_rcu(), hlist_bl_del_init_rcu(), hlist_bl_del_rcu(), hlist_nulls_del_init_rcu(), and hlist_nulls_del_rcu()) do plain stores into the ->next pointer of the preceding list elemment. Unfortunately, the compiler is within its rights to (for example) use byte-at-a-time writes to update the pointer, which would fatally confuse concurrent readers. This patch therefore adds the needed WRITE_ONCE() macros. KernelThreadSanitizer (KTSAN) reported the __hlist_del() issue, which is a problem when __hlist_del() is invoked by hlist_del_rcu(). Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'kernel/rcu/tree.c')
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