diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-23 11:30:28 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-23 11:30:28 -0700 |
commit | 30cb6d5f2eb24d15d20139d5ceefaccc68734bd7 (patch) | |
tree | 773c5a98645e4b945343caddcfe5af365566ccc5 /fs | |
parent | 4867faab1e3eb8cc3f74e390357615d9b8e8cda6 (diff) | |
parent | 68fa61c026057a39d6ccb850aa8785043afbee02 (diff) |
Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
hrtimers: Reorder clock bases
hrtimers: Avoid touching inactive timer bases
hrtimers: Make struct hrtimer_cpu_base layout less stupid
timerfd: Manage cancelable timers in timerfd
clockevents: Move C3 stop test outside lock
alarmtimer: Drop device refcount after rtc_open()
alarmtimer: Check return value of class_find_device()
timerfd: Allow timers to be cancelled when clock was set
hrtimers: Prepare for cancel on clock was set timers
Diffstat (limited to 'fs')
-rw-r--r-- | fs/timerfd.c | 102 |
1 files changed, 95 insertions, 7 deletions
diff --git a/fs/timerfd.c b/fs/timerfd.c index 8c4fc1425b3..f67acbdda5e 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) |