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timerfd: Add alarm timers
Add support for clocks CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM, thereby enabling wakeup alarm timers via file descriptors. Signed-off-by: Todd Poynor <toddpoynor@google.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
This commit is contained in:
Todd Poynor
John Stultz
parent
6cffe00f7d
commit
11ffa9d606
131
fs/timerfd.c
131
fs/timerfd.c
@ -8,6 +8,7 @@
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*
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*/
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#include <linux/alarmtimer.h>
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#include <linux/file.h>
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#include <linux/poll.h>
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#include <linux/init.h>
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@ -26,7 +27,10 @@
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#include <linux/rcupdate.h>
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struct timerfd_ctx {
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struct hrtimer tmr;
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union {
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struct hrtimer tmr;
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struct alarm alarm;
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} t;
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ktime_t tintv;
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ktime_t moffs;
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wait_queue_head_t wqh;
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@ -41,14 +45,19 @@ struct timerfd_ctx {
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static LIST_HEAD(cancel_list);
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static DEFINE_SPINLOCK(cancel_lock);
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static inline bool isalarm(struct timerfd_ctx *ctx)
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{
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return ctx->clockid == CLOCK_REALTIME_ALARM ||
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ctx->clockid == CLOCK_BOOTTIME_ALARM;
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}
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/*
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* This gets called when the timer event triggers. We set the "expired"
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* flag, but we do not re-arm the timer (in case it's necessary,
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* tintv.tv64 != 0) until the timer is accessed.
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*/
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static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
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static void timerfd_triggered(struct timerfd_ctx *ctx)
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{
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struct timerfd_ctx *ctx = container_of(htmr, struct timerfd_ctx, tmr);
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unsigned long flags;
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spin_lock_irqsave(&ctx->wqh.lock, flags);
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@ -56,10 +65,25 @@ static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
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ctx->ticks++;
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wake_up_locked(&ctx->wqh);
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spin_unlock_irqrestore(&ctx->wqh.lock, flags);
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}
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static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
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{
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struct timerfd_ctx *ctx = container_of(htmr, struct timerfd_ctx,
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t.tmr);
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timerfd_triggered(ctx);
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return HRTIMER_NORESTART;
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}
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static enum alarmtimer_restart timerfd_alarmproc(struct alarm *alarm,
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ktime_t now)
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{
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struct timerfd_ctx *ctx = container_of(alarm, struct timerfd_ctx,
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t.alarm);
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timerfd_triggered(ctx);
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return ALARMTIMER_NORESTART;
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}
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/*
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* Called when the clock was set to cancel the timers in the cancel
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* list. This will wake up processes waiting on these timers. The
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@ -107,8 +131,9 @@ static bool timerfd_canceled(struct timerfd_ctx *ctx)
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static void timerfd_setup_cancel(struct timerfd_ctx *ctx, int flags)
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{
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if (ctx->clockid == CLOCK_REALTIME && (flags & TFD_TIMER_ABSTIME) &&
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(flags & TFD_TIMER_CANCEL_ON_SET)) {
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if ((ctx->clockid == CLOCK_REALTIME ||
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ctx->clockid == CLOCK_REALTIME_ALARM) &&
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(flags & TFD_TIMER_ABSTIME) && (flags & TFD_TIMER_CANCEL_ON_SET)) {
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if (!ctx->might_cancel) {
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ctx->might_cancel = true;
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spin_lock(&cancel_lock);
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@ -124,7 +149,11 @@ static ktime_t timerfd_get_remaining(struct timerfd_ctx *ctx)
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{
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ktime_t remaining;
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remaining = hrtimer_expires_remaining(&ctx->tmr);
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if (isalarm(ctx))
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remaining = alarm_expires_remaining(&ctx->t.alarm);
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else
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remaining = hrtimer_expires_remaining(&ctx->t.tmr);
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return remaining.tv64 < 0 ? ktime_set(0, 0): remaining;
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}
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@ -142,11 +171,28 @@ static int timerfd_setup(struct timerfd_ctx *ctx, int flags,
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ctx->expired = 0;
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ctx->ticks = 0;
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ctx->tintv = timespec_to_ktime(ktmr->it_interval);
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hrtimer_init(&ctx->tmr, clockid, htmode);
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hrtimer_set_expires(&ctx->tmr, texp);
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ctx->tmr.function = timerfd_tmrproc;
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if (isalarm(ctx)) {
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alarm_init(&ctx->t.alarm,
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ctx->clockid == CLOCK_REALTIME_ALARM ?
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ALARM_REALTIME : ALARM_BOOTTIME,
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timerfd_alarmproc);
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} else {
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hrtimer_init(&ctx->t.tmr, clockid, htmode);
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hrtimer_set_expires(&ctx->t.tmr, texp);
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ctx->t.tmr.function = timerfd_tmrproc;
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}
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if (texp.tv64 != 0) {
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hrtimer_start(&ctx->tmr, texp, htmode);
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if (isalarm(ctx)) {
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if (flags & TFD_TIMER_ABSTIME)
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alarm_start(&ctx->t.alarm, texp);
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else
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alarm_start_relative(&ctx->t.alarm, texp);
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} else {
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hrtimer_start(&ctx->t.tmr, texp, htmode);
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}
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if (timerfd_canceled(ctx))
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return -ECANCELED;
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}
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@ -158,7 +204,11 @@ static int timerfd_release(struct inode *inode, struct file *file)
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struct timerfd_ctx *ctx = file->private_data;
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timerfd_remove_cancel(ctx);
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hrtimer_cancel(&ctx->tmr);
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if (isalarm(ctx))
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alarm_cancel(&ctx->t.alarm);
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else
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hrtimer_cancel(&ctx->t.tmr);
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kfree_rcu(ctx, rcu);
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return 0;
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}
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@ -215,9 +265,15 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
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* callback to avoid DoS attacks specifying a very
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* short timer period.
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*/
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ticks += hrtimer_forward_now(&ctx->tmr,
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ctx->tintv) - 1;
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hrtimer_restart(&ctx->tmr);
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if (isalarm(ctx)) {
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ticks += alarm_forward_now(
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&ctx->t.alarm, ctx->tintv) - 1;
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alarm_restart(&ctx->t.alarm);
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} else {
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ticks += hrtimer_forward_now(&ctx->t.tmr,
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ctx->tintv) - 1;
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hrtimer_restart(&ctx->t.tmr);
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}
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}
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ctx->expired = 0;
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ctx->ticks = 0;
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@ -259,7 +315,9 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
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if ((flags & ~TFD_CREATE_FLAGS) ||
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(clockid != CLOCK_MONOTONIC &&
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clockid != CLOCK_REALTIME))
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clockid != CLOCK_REALTIME &&
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clockid != CLOCK_REALTIME_ALARM &&
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clockid != CLOCK_BOOTTIME_ALARM))
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return -EINVAL;
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ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
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@ -268,7 +326,15 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
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init_waitqueue_head(&ctx->wqh);
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ctx->clockid = clockid;
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hrtimer_init(&ctx->tmr, clockid, HRTIMER_MODE_ABS);
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if (isalarm(ctx))
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alarm_init(&ctx->t.alarm,
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ctx->clockid == CLOCK_REALTIME_ALARM ?
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ALARM_REALTIME : ALARM_BOOTTIME,
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timerfd_alarmproc);
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else
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hrtimer_init(&ctx->t.tmr, clockid, HRTIMER_MODE_ABS);
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ctx->moffs = ktime_get_monotonic_offset();
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ufd = anon_inode_getfd("[timerfd]", &timerfd_fops, ctx,
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@ -305,8 +371,14 @@ static int do_timerfd_settime(int ufd, int flags,
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*/
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for (;;) {
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spin_lock_irq(&ctx->wqh.lock);
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if (hrtimer_try_to_cancel(&ctx->tmr) >= 0)
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break;
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if (isalarm(ctx)) {
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if (alarm_try_to_cancel(&ctx->t.alarm) >= 0)
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break;
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} else {
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if (hrtimer_try_to_cancel(&ctx->t.tmr) >= 0)
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break;
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}
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spin_unlock_irq(&ctx->wqh.lock);
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cpu_relax();
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}
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@ -317,8 +389,12 @@ static int do_timerfd_settime(int ufd, int flags,
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* We do not update "ticks" and "expired" since the timer will be
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* re-programmed again in the following timerfd_setup() call.
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*/
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if (ctx->expired && ctx->tintv.tv64)
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hrtimer_forward_now(&ctx->tmr, ctx->tintv);
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if (ctx->expired && ctx->tintv.tv64) {
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if (isalarm(ctx))
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alarm_forward_now(&ctx->t.alarm, ctx->tintv);
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else
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hrtimer_forward_now(&ctx->t.tmr, ctx->tintv);
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}
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old->it_value = ktime_to_timespec(timerfd_get_remaining(ctx));
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old->it_interval = ktime_to_timespec(ctx->tintv);
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@ -345,9 +421,18 @@ static int do_timerfd_gettime(int ufd, struct itimerspec *t)
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spin_lock_irq(&ctx->wqh.lock);
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if (ctx->expired && ctx->tintv.tv64) {
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ctx->expired = 0;
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ctx->ticks +=
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hrtimer_forward_now(&ctx->tmr, ctx->tintv) - 1;
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hrtimer_restart(&ctx->tmr);
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if (isalarm(ctx)) {
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ctx->ticks +=
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alarm_forward_now(
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&ctx->t.alarm, ctx->tintv) - 1;
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alarm_restart(&ctx->t.alarm);
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} else {
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ctx->ticks +=
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hrtimer_forward_now(&ctx->t.tmr, ctx->tintv)
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- 1;
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hrtimer_restart(&ctx->t.tmr);
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}
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}
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t->it_value = ktime_to_timespec(timerfd_get_remaining(ctx));
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t->it_interval = ktime_to_timespec(ctx->tintv);
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