xfs: remove confusing ail cursor wrapper

[~andy/linux] / fs / timerfd.c

diff --git a/fs/timerfd.c b/fs/timerfd.c
index 7e14c9e7c4ee97b8a15700d463846777a9592ac8..f67acbdda5e8c13fce54e51f72fe0882f2fa94da 100644 (file)
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -22,6 +22,7 @@
 #include <linux/anon_inodes.h>
 #include <linux/timerfd.h>
 #include <linux/syscalls.h>
+#include <linux/rcupdate.h>
 
 struct timerfd_ctx {
        struct hrtimer tmr;
@@ -31,9 +32,14 @@ struct timerfd_ctx {
        u64 ticks;
        int expired;
        int clockid;
+       struct rcu_head rcu;
+       struct list_head clist;
        bool might_cancel;
 };
 
+static LIST_HEAD(cancel_list);
+static DEFINE_SPINLOCK(cancel_lock);
+
 /*
  * This gets called when the timer event triggers. We set the "expired"
  * flag, but we do not re-arm the timer (in case it's necessary,
@@ -53,28 +59,69 @@ static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
        return HRTIMER_NORESTART;
 }
 
-static ktime_t timerfd_get_remaining(struct timerfd_ctx *ctx)
+/*
+ * Called when the clock was set to cancel the timers in the cancel
+ * list.
+ */
+void timerfd_clock_was_set(void)
 {
-       ktime_t remaining;
+       ktime_t moffs = ktime_get_monotonic_offset();
+       struct timerfd_ctx *ctx;
+       unsigned long flags;
 
-       remaining = hrtimer_expires_remaining(&ctx->tmr);
-       return remaining.tv64 < 0 ? ktime_set(0, 0): remaining;
+       rcu_read_lock();
+       list_for_each_entry_rcu(ctx, &cancel_list, clist) {
+               if (!ctx->might_cancel)
+                       continue;
+               spin_lock_irqsave(&ctx->wqh.lock, flags);
+               if (ctx->moffs.tv64 != moffs.tv64) {
+                       ctx->moffs.tv64 = KTIME_MAX;
+                       wake_up_locked(&ctx->wqh);
+               }
+               spin_unlock_irqrestore(&ctx->wqh.lock, flags);
+       }
+       rcu_read_unlock();
 }
 
-static bool timerfd_canceled(struct timerfd_ctx *ctx)
+static void timerfd_remove_cancel(struct timerfd_ctx *ctx)
 {
-       ktime_t moffs;
+       if (ctx->might_cancel) {
+               ctx->might_cancel = false;
+               spin_lock(&cancel_lock);
+               list_del_rcu(&ctx->clist);
+               spin_unlock(&cancel_lock);
+       }
+}
 
-       if (!ctx->might_cancel)
+static bool timerfd_canceled(struct timerfd_ctx *ctx)
+{
+       if (!ctx->might_cancel || ctx->moffs.tv64 != KTIME_MAX)
                return false;
+       ctx->moffs = ktime_get_monotonic_offset();
+       return true;
+}
 
-       moffs = ktime_get_monotonic_offset();
+static void timerfd_setup_cancel(struct timerfd_ctx *ctx, int flags)
+{
+       if (ctx->clockid == CLOCK_REALTIME && (flags & TFD_TIMER_ABSTIME) &&
+           (flags & TFD_TIMER_CANCEL_ON_SET)) {
+               if (!ctx->might_cancel) {
+                       ctx->might_cancel = true;
+                       spin_lock(&cancel_lock);
+                       list_add_rcu(&ctx->clist, &cancel_list);
+                       spin_unlock(&cancel_lock);
+               }
+       } else if (ctx->might_cancel) {
+               timerfd_remove_cancel(ctx);
+       }
+}
 
-       if (moffs.tv64 == ctx->moffs.tv64)
-               return false;
+static ktime_t timerfd_get_remaining(struct timerfd_ctx *ctx)
+{
+       ktime_t remaining;
 
-       ctx->moffs = moffs;
-       return true;
+       remaining = hrtimer_expires_remaining(&ctx->tmr);
+       return remaining.tv64 < 0 ? ktime_set(0, 0): remaining;
 }
 
 static int timerfd_setup(struct timerfd_ctx *ctx, int flags,
@@ -87,13 +134,6 @@ static int timerfd_setup(struct timerfd_ctx *ctx, int flags,
        htmode = (flags & TFD_TIMER_ABSTIME) ?
                HRTIMER_MODE_ABS: HRTIMER_MODE_REL;
 
-       ctx->might_cancel = false;
-       if (htmode == HRTIMER_MODE_ABS && ctx->clockid == CLOCK_REALTIME &&
-           (flags & TFD_TIMER_CANCELON_SET)) {
-               clockid = CLOCK_REALTIME_COS;
-               ctx->might_cancel = true;
-       }
-
        texp = timespec_to_ktime(ktmr->it_value);
        ctx->expired = 0;
        ctx->ticks = 0;
@@ -113,8 +153,9 @@ static int timerfd_release(struct inode *inode, struct file *file)
 {
        struct timerfd_ctx *ctx = file->private_data;
 
+       timerfd_remove_cancel(ctx);
        hrtimer_cancel(&ctx->tmr);
-       kfree(ctx);
+       kfree_rcu(ctx, rcu);
        return 0;
 }
 
@@ -149,20 +190,20 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
        else
                res = wait_event_interruptible_locked_irq(ctx->wqh, ctx->ticks);
 
+       /*
+        * If clock has changed, we do not care about the
+        * ticks and we do not rearm the timer. Userspace must
+        * reevaluate anyway.
+        */
+       if (timerfd_canceled(ctx)) {
+               ctx->ticks = 0;
+               ctx->expired = 0;
+               res = -ECANCELED;
+       }
+
        if (ctx->ticks) {
                ticks = ctx->ticks;
 
-               /*
-                * If clock has changed, we do not care about the
-                * ticks and we do not rearm the timer. Userspace must
-                * reevaluate anyway.
-                */
-               if (timerfd_canceled(ctx)) {
-                       ticks = 0;
-                       ctx->expired = 0;
-                       res = -ECANCELED;
-               }
-
                if (ctx->expired && ctx->tintv.tv64) {
                        /*
                         * If tintv.tv64 != 0, this is a periodic timer that
@@ -258,6 +299,8 @@ SYSCALL_DEFINE4(timerfd_settime, int, ufd, int, flags,
                return PTR_ERR(file);
        ctx = file->private_data;
 
+       timerfd_setup_cancel(ctx, flags);
+
        /*
         * We need to stop the existing timer before reprogramming
         * it to the new values.