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authorLinus Torvalds <torvalds@linux-foundation.org>2016-07-25 12:41:29 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-25 12:41:29 -0700
commitc86ad14d305d2429c3da19462440bac50c183def (patch)
treebd794cd72476661faf82c440063c217bb978ce44 /net
parenta2303849a6b4b7ba59667091e00d6bb194071d9a (diff)
parentf06628638cf6e75f179742b6c1b35076965b9fdd (diff)
Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar: "The locking tree was busier in this cycle than the usual pattern - a couple of major projects happened to coincide. The main changes are: - implement the atomic_fetch_{add,sub,and,or,xor}() API natively across all SMP architectures (Peter Zijlstra) - add atomic_fetch_{inc/dec}() as well, using the generic primitives (Davidlohr Bueso) - optimize various aspects of rwsems (Jason Low, Davidlohr Bueso, Waiman Long) - optimize smp_cond_load_acquire() on arm64 and implement LSE based atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() on arm64 (Will Deacon) - introduce smp_acquire__after_ctrl_dep() and fix various barrier mis-uses and bugs (Peter Zijlstra) - after discovering ancient spin_unlock_wait() barrier bugs in its implementation and usage, strengthen its semantics and update/fix usage sites (Peter Zijlstra) - optimize mutex_trylock() fastpath (Peter Zijlstra) - ... misc fixes and cleanups" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (67 commits) locking/atomic: Introduce inc/dec variants for the atomic_fetch_$op() API locking/barriers, arch/arm64: Implement LDXR+WFE based smp_cond_load_acquire() locking/static_keys: Fix non static symbol Sparse warning locking/qspinlock: Use __this_cpu_dec() instead of full-blown this_cpu_dec() locking/atomic, arch/tile: Fix tilepro build locking/atomic, arch/m68k: Remove comment locking/atomic, arch/arc: Fix build locking/Documentation: Clarify limited control-dependency scope locking/atomic, arch/rwsem: Employ atomic_long_fetch_add() locking/atomic, arch/qrwlock: Employ atomic_fetch_add_acquire() locking/atomic, arch/mips: Convert to _relaxed atomics locking/atomic, arch/alpha: Convert to _relaxed atomics locking/atomic: Remove the deprecated atomic_{set,clear}_mask() functions locking/atomic: Remove linux/atomic.h:atomic_fetch_or() locking/atomic: Implement atomic{,64,_long}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() locking/atomic: Fix atomic64_relaxed() bits locking/atomic, arch/xtensa: Implement atomic_fetch_{add,sub,and,or,xor}() locking/atomic, arch/x86: Implement atomic{,64}_fetch_{add,sub,and,or,xor}() locking/atomic, arch/tile: Implement atomic{,64}_fetch_{add,sub,and,or,xor}() locking/atomic, arch/sparc: Implement atomic{,64}_fetch_{add,sub,and,or,xor}() ...
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/nf_conntrack_core.c23
1 files changed, 22 insertions, 1 deletions
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 9f530adad10d..4cbda4bd8926 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -83,6 +83,13 @@ void nf_conntrack_lock(spinlock_t *lock) __acquires(lock)
spin_lock(lock);
while (unlikely(nf_conntrack_locks_all)) {
spin_unlock(lock);
+
+ /*
+ * Order the 'nf_conntrack_locks_all' load vs. the
+ * spin_unlock_wait() loads below, to ensure
+ * that 'nf_conntrack_locks_all_lock' is indeed held:
+ */
+ smp_rmb(); /* spin_lock(&nf_conntrack_locks_all_lock) */
spin_unlock_wait(&nf_conntrack_locks_all_lock);
spin_lock(lock);
}
@@ -128,6 +135,14 @@ static void nf_conntrack_all_lock(void)
spin_lock(&nf_conntrack_locks_all_lock);
nf_conntrack_locks_all = true;
+ /*
+ * Order the above store of 'nf_conntrack_locks_all' against
+ * the spin_unlock_wait() loads below, such that if
+ * nf_conntrack_lock() observes 'nf_conntrack_locks_all'
+ * we must observe nf_conntrack_locks[] held:
+ */
+ smp_mb(); /* spin_lock(&nf_conntrack_locks_all_lock) */
+
for (i = 0; i < CONNTRACK_LOCKS; i++) {
spin_unlock_wait(&nf_conntrack_locks[i]);
}
@@ -135,7 +150,13 @@ static void nf_conntrack_all_lock(void)
static void nf_conntrack_all_unlock(void)
{
- nf_conntrack_locks_all = false;
+ /*
+ * All prior stores must be complete before we clear
+ * 'nf_conntrack_locks_all'. Otherwise nf_conntrack_lock()
+ * might observe the false value but not the entire
+ * critical section:
+ */
+ smp_store_release(&nf_conntrack_locks_all, false);
spin_unlock(&nf_conntrack_locks_all_lock);
}