timerfd: Protect the might cancel mechanism proper

[pandora-kernel.git] / fs / timerfd.c

diff --git a/fs/timerfd.c b/fs/timerfd.c
index dffeb37..b2c7dd7 100644 (file)
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -34,6 +34,7 @@ struct timerfd_ctx {
        int clockid;
        struct rcu_head rcu;
        struct list_head clist;
+       spinlock_t cancel_lock;
        bool might_cancel;
 };
 
@@ -86,7 +87,7 @@ void timerfd_clock_was_set(void)
        rcu_read_unlock();
 }
 
-static void timerfd_remove_cancel(struct timerfd_ctx *ctx)
+static void __timerfd_remove_cancel(struct timerfd_ctx *ctx)
 {
        if (ctx->might_cancel) {
                ctx->might_cancel = false;
@@ -96,6 +97,13 @@ static void timerfd_remove_cancel(struct timerfd_ctx *ctx)
        }
 }
 
+static void timerfd_remove_cancel(struct timerfd_ctx *ctx)
+{
+       spin_lock(&ctx->cancel_lock);
+       __timerfd_remove_cancel(ctx);
+       spin_unlock(&ctx->cancel_lock);
+}
+
 static bool timerfd_canceled(struct timerfd_ctx *ctx)
 {
        if (!ctx->might_cancel || ctx->moffs.tv64 != KTIME_MAX)
@@ -106,6 +114,7 @@ static bool timerfd_canceled(struct timerfd_ctx *ctx)
 
 static void timerfd_setup_cancel(struct timerfd_ctx *ctx, int flags)
 {
+       spin_lock(&ctx->cancel_lock);
        if (ctx->clockid == CLOCK_REALTIME && (flags & TFD_TIMER_ABSTIME) &&
            (flags & TFD_TIMER_CANCEL_ON_SET)) {
                if (!ctx->might_cancel) {
@@ -114,16 +123,17 @@ static void timerfd_setup_cancel(struct timerfd_ctx *ctx, int flags)
                        list_add_rcu(&ctx->clist, &cancel_list);
                        spin_unlock(&cancel_lock);
                }
-       } else if (ctx->might_cancel) {
-               timerfd_remove_cancel(ctx);
+       } else {
+               __timerfd_remove_cancel(ctx);
        }
+       spin_unlock(&ctx->cancel_lock);
 }
 
 static ktime_t timerfd_get_remaining(struct timerfd_ctx *ctx)
 {
        ktime_t remaining;
 
-       remaining = hrtimer_expires_remaining(&ctx->tmr);
+       remaining = hrtimer_expires_remaining_adjusted(&ctx->tmr);
        return remaining.tv64 < 0 ? ktime_set(0, 0): remaining;
 }
 
@@ -268,6 +278,7 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
                return -ENOMEM;
 
        init_waitqueue_head(&ctx->wqh);
+       spin_lock_init(&ctx->cancel_lock);
        ctx->clockid = clockid;
        hrtimer_init(&ctx->tmr, clockid, HRTIMER_MODE_ABS);
        ctx->moffs = ktime_get_monotonic_offset();