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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2015-02-21 21:45:03 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-02-21 21:45:03 +0300 |
| commit | 10436cf8812edadcc1813dbda39a69e9965caee6 (patch) | |
| tree | 5659ab914ddda91fac03556cc8d38f13fe87e185 /arch/x86/xen | |
| parent | 5fbe4c224ce3e2e62bd487158dfd1e89f9ae3e11 (diff) | |
| parent | d6abfdb2022368d8c6c4be3f11a06656601a6cc2 (diff) | |
| download | linux-10436cf8812edadcc1813dbda39a69e9965caee6.tar.xz | |
Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Ingo Molnar:
"Two fixes: the paravirt spin_unlock() corruption/crash fix, and an
rtmutex NULL dereference crash fix"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/spinlocks/paravirt: Fix memory corruption on unlock
locking/rtmutex: Avoid a NULL pointer dereference on deadlock
Diffstat (limited to 'arch/x86/xen')
| -rw-r--r-- | arch/x86/xen/spinlock.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c index 23b45eb9a89c..956374c1edbc 100644 --- a/arch/x86/xen/spinlock.c +++ b/arch/x86/xen/spinlock.c @@ -41,7 +41,7 @@ static u8 zero_stats; static inline void check_zero(void) { u8 ret; - u8 old = ACCESS_ONCE(zero_stats); + u8 old = READ_ONCE(zero_stats); if (unlikely(old)) { ret = cmpxchg(&zero_stats, old, 0); /* This ensures only one fellow resets the stat */ @@ -112,6 +112,7 @@ __visible void xen_lock_spinning(struct arch_spinlock *lock, __ticket_t want) struct xen_lock_waiting *w = this_cpu_ptr(&lock_waiting); int cpu = smp_processor_id(); u64 start; + __ticket_t head; unsigned long flags; /* If kicker interrupts not initialized yet, just spin */ @@ -159,11 +160,15 @@ __visible void xen_lock_spinning(struct arch_spinlock *lock, __ticket_t want) */ __ticket_enter_slowpath(lock); + /* make sure enter_slowpath, which is atomic does not cross the read */ + smp_mb__after_atomic(); + /* * check again make sure it didn't become free while * we weren't looking */ - if (ACCESS_ONCE(lock->tickets.head) == want) { + head = READ_ONCE(lock->tickets.head); + if (__tickets_equal(head, want)) { add_stats(TAKEN_SLOW_PICKUP, 1); goto out; } @@ -204,8 +209,8 @@ static void xen_unlock_kick(struct arch_spinlock *lock, __ticket_t next) const struct xen_lock_waiting *w = &per_cpu(lock_waiting, cpu); /* Make sure we read lock before want */ - if (ACCESS_ONCE(w->lock) == lock && - ACCESS_ONCE(w->want) == next) { + if (READ_ONCE(w->lock) == lock && + READ_ONCE(w->want) == next) { add_stats(RELEASED_SLOW_KICKED, 1); xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR); break; |