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author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2013-08-23 09:40:42 -0700 |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2013-09-23 09:13:49 -0700 |
commit | 2a855b644c310d5db5a80b8816c0c7748c167977 (patch) | |
tree | c39eb7a56033c40a380b45b8928ab377722e6b02 /kernel/rcutree.c | |
parent | 829511d8aa7a2179bba57ab4ab277d6f9c77ae5b (diff) | |
download | op-kernel-dev-2a855b644c310d5db5a80b8816c0c7748c167977.zip op-kernel-dev-2a855b644c310d5db5a80b8816c0c7748c167977.tar.gz |
rcu: Make list_splice_init_rcu() account for RCU readers
The list_splice_init_rcu() function allows a list visible to RCU readers
to be spliced into another list visible to RCU readers. This is OK,
except for the use of INIT_LIST_HEAD(), which does pointer updates
without doing anything to make those updates safe for concurrent readers.
Of course, most of the time INIT_LIST_HEAD() is being used in reader-free
contexts, such as initialization or cleanup, so it is OK for it to update
pointers in an unsafe-for-RCU-readers manner. This commit therefore
creates an INIT_LIST_HEAD_RCU() that uses ACCESS_ONCE() to make the updates
reader-safe. The reason that we can use ACCESS_ONCE() instead of the more
typical rcu_assign_pointer() is that list_splice_init_rcu() is updating the
pointers to reference something that is already visible to readers, so
that there is no problem with pre-initialized values.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree.c')
0 files changed, 0 insertions, 0 deletions