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Diffstat (limited to 'fs/timerfd.c')
-rw-r--r--fs/timerfd.c102
1 files changed, 95 insertions, 7 deletions
diff --git a/fs/timerfd.c b/fs/timerfd.c
index 8c4fc1425b3e..f67acbdda5e8 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -22,16 +22,24 @@
#include <linux/anon_inodes.h>
#include <linux/timerfd.h>
#include <linux/syscalls.h>
+#include <linux/rcupdate.h>
struct timerfd_ctx {
struct hrtimer tmr;
ktime_t tintv;
+ ktime_t moffs;
wait_queue_head_t wqh;
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,
@@ -51,6 +59,63 @@ static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
return HRTIMER_NORESTART;
}
+/*
+ * Called when the clock was set to cancel the timers in the cancel
+ * list.
+ */
+void timerfd_clock_was_set(void)
+{
+ ktime_t moffs = ktime_get_monotonic_offset();
+ struct timerfd_ctx *ctx;
+ unsigned long flags;
+
+ 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 void timerfd_remove_cancel(struct timerfd_ctx *ctx)
+{
+ if (ctx->might_cancel) {
+ ctx->might_cancel = false;
+ spin_lock(&cancel_lock);
+ list_del_rcu(&ctx->clist);
+ spin_unlock(&cancel_lock);
+ }
+}
+
+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;
+}
+
+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);
+ }
+}
+
static ktime_t timerfd_get_remaining(struct timerfd_ctx *ctx)
{
ktime_t remaining;
@@ -59,11 +124,12 @@ static ktime_t timerfd_get_remaining(struct timerfd_ctx *ctx)
return remaining.tv64 < 0 ? ktime_set(0, 0): remaining;
}
-static void timerfd_setup(struct timerfd_ctx *ctx, int flags,
- const struct itimerspec *ktmr)
+static int timerfd_setup(struct timerfd_ctx *ctx, int flags,
+ const struct itimerspec *ktmr)
{
enum hrtimer_mode htmode;
ktime_t texp;
+ int clockid = ctx->clockid;
htmode = (flags & TFD_TIMER_ABSTIME) ?
HRTIMER_MODE_ABS: HRTIMER_MODE_REL;
@@ -72,19 +138,24 @@ static void timerfd_setup(struct timerfd_ctx *ctx, int flags,
ctx->expired = 0;
ctx->ticks = 0;
ctx->tintv = timespec_to_ktime(ktmr->it_interval);
- hrtimer_init(&ctx->tmr, ctx->clockid, htmode);
+ hrtimer_init(&ctx->tmr, clockid, htmode);
hrtimer_set_expires(&ctx->tmr, texp);
ctx->tmr.function = timerfd_tmrproc;
- if (texp.tv64 != 0)
+ if (texp.tv64 != 0) {
hrtimer_start(&ctx->tmr, texp, htmode);
+ if (timerfd_canceled(ctx))
+ return -ECANCELED;
+ }
+ return 0;
}
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;
}
@@ -118,8 +189,21 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
res = -EAGAIN;
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 (ctx->expired && ctx->tintv.tv64) {
/*
* If tintv.tv64 != 0, this is a periodic timer that
@@ -183,6 +267,7 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
init_waitqueue_head(&ctx->wqh);
ctx->clockid = clockid;
hrtimer_init(&ctx->tmr, clockid, HRTIMER_MODE_ABS);
+ ctx->moffs = ktime_get_monotonic_offset();
ufd = anon_inode_getfd("[timerfd]", &timerfd_fops, ctx,
O_RDWR | (flags & TFD_SHARED_FCNTL_FLAGS));
@@ -199,6 +284,7 @@ SYSCALL_DEFINE4(timerfd_settime, int, ufd, int, flags,
struct file *file;
struct timerfd_ctx *ctx;
struct itimerspec ktmr, kotmr;
+ int ret;
if (copy_from_user(&ktmr, utmr, sizeof(ktmr)))
return -EFAULT;
@@ -213,6 +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.
@@ -240,14 +328,14 @@ SYSCALL_DEFINE4(timerfd_settime, int, ufd, int, flags,
/*
* Re-program the timer to the new value ...
*/
- timerfd_setup(ctx, flags, &ktmr);
+ ret = timerfd_setup(ctx, flags, &ktmr);
spin_unlock_irq(&ctx->wqh.lock);
fput(file);
if (otmr && copy_to_user(otmr, &kotmr, sizeof(kotmr)))
return -EFAULT;
- return 0;
+ return ret;
}
SYSCALL_DEFINE2(timerfd_gettime, int, ufd, struct itimerspec __user *, otmr)