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author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-08-12 20:54:21 (GMT) |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-09-16 17:08:03 (GMT) |
commit | c847f14217d5aec5336272a54a32ffcf6e06ddcb (patch) | |
tree | 865d138fe6a772c37c4928518b257bb14834c793 /kernel/rcu/tiny.c | |
parent | 1772947bd0126661866069157e95197e9c0020e9 (diff) | |
download | linux-c847f14217d5aec5336272a54a32ffcf6e06ddcb.tar.xz |
rcu: Avoid misordering in nocb_leader_wait()
The NOCB follower wakeup ordering depends on the store to the tail
pointer happening before the wakeup. However, because atomic_long_add()
does not return a value, it does not provide ordering guarantees, and
the locking in wake_up() only guarantees that the store will happen
before the unlock, which might be too late. Even though this is only a
theoretical issue, this commit adds a smp_mb__after_atomic() after the
final atomic_long_add() to provide the needed ordering guarantee.
Reported-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Diffstat (limited to 'kernel/rcu/tiny.c')
0 files changed, 0 insertions, 0 deletions