Enable wakeup alarm timers via file descriptors. Hook up alarmtimer
to timerfd via clocks CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM,
and add needed functions to alarmtimer.
fs/timerfd.c | 131 +++++++++++++++++++++++++++++++++++++--------
include/linux/alarmtimer.h | 4 +
kernel/time/alarmtimer.c | 39 +++++++++++++
3 files changed, 150 insertions(+), 24 deletions(-)
Add functions needed for hooking up alarmtimer to timerfd:
* alarm_restart: Similar to hrtimer_restart, restart an alarmtimer after
the expires time has already been updated (as with alarm_forward).
* alarm_forward_now: Similar to hrtimer_forward_now, move the expires
time forward to an interval from the current time of the associated clock.
* alarm_start_relative: Start an alarmtimer with an expires time relative to
the current time of the associated clock.
* alarm_expires_remaining: Similar to hrtimer_expires_remaining, return the
amount of time remaining until alarm expiry.
Signed-off-by: Todd Poynor <[email protected]>
---
include/linux/alarmtimer.h | 4 ++++
kernel/time/alarmtimer.c | 39 ++++++++++++++++++++++++++++++++++++++-
2 files changed, 42 insertions(+), 1 deletion(-)
diff --git a/include/linux/alarmtimer.h b/include/linux/alarmtimer.h
index 9069694..a899402 100644
--- a/include/linux/alarmtimer.h
+++ b/include/linux/alarmtimer.h
@@ -44,10 +44,14 @@ struct alarm {
void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
enum alarmtimer_restart (*function)(struct alarm *, ktime_t));
int alarm_start(struct alarm *alarm, ktime_t start);
+int alarm_start_relative(struct alarm *alarm, ktime_t start);
+void alarm_restart(struct alarm *alarm);
int alarm_try_to_cancel(struct alarm *alarm);
int alarm_cancel(struct alarm *alarm);
u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval);
+u64 alarm_forward_now(struct alarm *alarm, ktime_t interval);
+ktime_t alarm_expires_remaining(const struct alarm *alarm);
/* Provide way to access the rtc device being used by alarmtimers */
struct rtc_device *alarmtimer_get_rtcdev(void);
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index f11d83b..3e5cba2 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -199,6 +199,12 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
}
+ktime_t alarm_expires_remaining(const struct alarm *alarm)
+{
+ struct alarm_base *base = &alarm_bases[alarm->type];
+ return ktime_sub(alarm->node.expires, base->gettime());
+}
+
#ifdef CONFIG_RTC_CLASS
/**
* alarmtimer_suspend - Suspend time callback
@@ -305,7 +311,7 @@ void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
}
/**
- * alarm_start - Sets an alarm to fire
+ * alarm_start - Sets an absolute alarm to fire
* @alarm: ptr to alarm to set
* @start: time to run the alarm
*/
@@ -325,6 +331,31 @@ int alarm_start(struct alarm *alarm, ktime_t start)
}
/**
+ * alarm_start_relative - Sets a relative alarm to fire
+ * @alarm: ptr to alarm to set
+ * @start: time relative to now to run the alarm
+ */
+int alarm_start_relative(struct alarm *alarm, ktime_t start)
+{
+ struct alarm_base *base = &alarm_bases[alarm->type];
+
+ start = ktime_add(start, base->gettime());
+ return alarm_start(alarm, start);
+}
+
+void alarm_restart(struct alarm *alarm)
+{
+ struct alarm_base *base = &alarm_bases[alarm->type];
+ unsigned long flags;
+
+ spin_lock_irqsave(&base->lock, flags);
+ hrtimer_set_expires(&alarm->timer, alarm->node.expires);
+ hrtimer_restart(&alarm->timer);
+ alarmtimer_enqueue(base, alarm);
+ spin_unlock_irqrestore(&base->lock, flags);
+}
+
+/**
* alarm_try_to_cancel - Tries to cancel an alarm timer
* @alarm: ptr to alarm to be canceled
*
@@ -394,6 +425,12 @@ u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
return overrun;
}
+u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
+{
+ struct alarm_base *base = &alarm_bases[alarm->type];
+
+ return alarm_forward(alarm, base->gettime(), interval);
+}
--
1.8.2.1
Add support for clocks CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM,
thereby enabling wakeup alarm timers via file descriptors.
Signed-off-by: Todd Poynor <[email protected]>
---
fs/timerfd.c | 131 ++++++++++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 108 insertions(+), 23 deletions(-)
diff --git a/fs/timerfd.c b/fs/timerfd.c
index 32b644f..9293121 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -8,6 +8,7 @@
*
*/
+#include <linux/alarmtimer.h>
#include <linux/file.h>
#include <linux/poll.h>
#include <linux/init.h>
@@ -26,7 +27,10 @@
#include <linux/rcupdate.h>
struct timerfd_ctx {
- struct hrtimer tmr;
+ union {
+ struct hrtimer tmr;
+ struct alarm alarm;
+ } t;
ktime_t tintv;
ktime_t moffs;
wait_queue_head_t wqh;
@@ -41,14 +45,19 @@ struct timerfd_ctx {
static LIST_HEAD(cancel_list);
static DEFINE_SPINLOCK(cancel_lock);
+static inline bool isalarm(struct timerfd_ctx *ctx)
+{
+ return ctx->clockid == CLOCK_REALTIME_ALARM ||
+ ctx->clockid == CLOCK_BOOTTIME_ALARM;
+}
+
/*
* 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,
* tintv.tv64 != 0) until the timer is accessed.
*/
-static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
+static void timerfd_triggered(struct timerfd_ctx *ctx)
{
- struct timerfd_ctx *ctx = container_of(htmr, struct timerfd_ctx, tmr);
unsigned long flags;
spin_lock_irqsave(&ctx->wqh.lock, flags);
@@ -56,10 +65,25 @@ static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
ctx->ticks++;
wake_up_locked(&ctx->wqh);
spin_unlock_irqrestore(&ctx->wqh.lock, flags);
+}
+static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
+{
+ struct timerfd_ctx *ctx = container_of(htmr, struct timerfd_ctx,
+ t.tmr);
+ timerfd_triggered(ctx);
return HRTIMER_NORESTART;
}
+static enum alarmtimer_restart timerfd_alarmproc(struct alarm *alarm,
+ ktime_t now)
+{
+ struct timerfd_ctx *ctx = container_of(alarm, struct timerfd_ctx,
+ t.alarm);
+ timerfd_triggered(ctx);
+ return ALARMTIMER_NORESTART;
+}
+
/*
* Called when the clock was set to cancel the timers in the cancel
* list. This will wake up processes waiting on these timers. The
@@ -107,8 +131,9 @@ static bool timerfd_canceled(struct timerfd_ctx *ctx)
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->clockid == CLOCK_REALTIME ||
+ ctx->clockid == CLOCK_REALTIME_ALARM) &&
+ (flags & TFD_TIMER_ABSTIME) && (flags & TFD_TIMER_CANCEL_ON_SET)) {
if (!ctx->might_cancel) {
ctx->might_cancel = true;
spin_lock(&cancel_lock);
@@ -124,7 +149,11 @@ static ktime_t timerfd_get_remaining(struct timerfd_ctx *ctx)
{
ktime_t remaining;
- remaining = hrtimer_expires_remaining(&ctx->tmr);
+ if (isalarm(ctx))
+ remaining = alarm_expires_remaining(&ctx->t.alarm);
+ else
+ remaining = hrtimer_expires_remaining(&ctx->t.tmr);
+
return remaining.tv64 < 0 ? ktime_set(0, 0): remaining;
}
@@ -142,11 +171,28 @@ static int 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, clockid, htmode);
- hrtimer_set_expires(&ctx->tmr, texp);
- ctx->tmr.function = timerfd_tmrproc;
+
+ if (isalarm(ctx)) {
+ alarm_init(&ctx->t.alarm,
+ ctx->clockid == CLOCK_REALTIME_ALARM ?
+ ALARM_REALTIME : ALARM_BOOTTIME,
+ timerfd_alarmproc);
+ } else {
+ hrtimer_init(&ctx->t.tmr, clockid, htmode);
+ hrtimer_set_expires(&ctx->t.tmr, texp);
+ ctx->t.tmr.function = timerfd_tmrproc;
+ }
+
if (texp.tv64 != 0) {
- hrtimer_start(&ctx->tmr, texp, htmode);
+ if (isalarm(ctx)) {
+ if (flags & TFD_TIMER_ABSTIME)
+ alarm_start(&ctx->t.alarm, texp);
+ else
+ alarm_start_relative(&ctx->t.alarm, texp);
+ } else {
+ hrtimer_start(&ctx->t.tmr, texp, htmode);
+ }
+
if (timerfd_canceled(ctx))
return -ECANCELED;
}
@@ -158,7 +204,11 @@ 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);
+
+ if (isalarm(ctx))
+ alarm_cancel(&ctx->t.alarm);
+ else
+ hrtimer_cancel(&ctx->t.tmr);
kfree_rcu(ctx, rcu);
return 0;
}
@@ -215,9 +265,15 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
* callback to avoid DoS attacks specifying a very
* short timer period.
*/
- ticks += hrtimer_forward_now(&ctx->tmr,
- ctx->tintv) - 1;
- hrtimer_restart(&ctx->tmr);
+ if (isalarm(ctx)) {
+ ticks += alarm_forward_now(
+ &ctx->t.alarm, ctx->tintv) - 1;
+ alarm_restart(&ctx->t.alarm);
+ } else {
+ ticks += hrtimer_forward_now(&ctx->t.tmr,
+ ctx->tintv) - 1;
+ hrtimer_restart(&ctx->t.tmr);
+ }
}
ctx->expired = 0;
ctx->ticks = 0;
@@ -259,7 +315,9 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
if ((flags & ~TFD_CREATE_FLAGS) ||
(clockid != CLOCK_MONOTONIC &&
- clockid != CLOCK_REALTIME))
+ clockid != CLOCK_REALTIME &&
+ clockid != CLOCK_REALTIME_ALARM &&
+ clockid != CLOCK_BOOTTIME_ALARM))
return -EINVAL;
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
@@ -268,7 +326,15 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
init_waitqueue_head(&ctx->wqh);
ctx->clockid = clockid;
- hrtimer_init(&ctx->tmr, clockid, HRTIMER_MODE_ABS);
+
+ if (isalarm(ctx))
+ alarm_init(&ctx->t.alarm,
+ ctx->clockid == CLOCK_REALTIME_ALARM ?
+ ALARM_REALTIME : ALARM_BOOTTIME,
+ timerfd_alarmproc);
+ else
+ hrtimer_init(&ctx->t.tmr, clockid, HRTIMER_MODE_ABS);
+
ctx->moffs = ktime_get_monotonic_offset();
ufd = anon_inode_getfd("[timerfd]", &timerfd_fops, ctx,
@@ -305,8 +371,14 @@ static int do_timerfd_settime(int ufd, int flags,
*/
for (;;) {
spin_lock_irq(&ctx->wqh.lock);
- if (hrtimer_try_to_cancel(&ctx->tmr) >= 0)
- break;
+
+ if (isalarm(ctx)) {
+ if (alarm_try_to_cancel(&ctx->t.alarm) >= 0)
+ break;
+ } else {
+ if (hrtimer_try_to_cancel(&ctx->t.tmr) >= 0)
+ break;
+ }
spin_unlock_irq(&ctx->wqh.lock);
cpu_relax();
}
@@ -317,8 +389,12 @@ static int do_timerfd_settime(int ufd, int flags,
* We do not update "ticks" and "expired" since the timer will be
* re-programmed again in the following timerfd_setup() call.
*/
- if (ctx->expired && ctx->tintv.tv64)
- hrtimer_forward_now(&ctx->tmr, ctx->tintv);
+ if (ctx->expired && ctx->tintv.tv64) {
+ if (isalarm(ctx))
+ alarm_forward_now(&ctx->t.alarm, ctx->tintv);
+ else
+ hrtimer_forward_now(&ctx->t.tmr, ctx->tintv);
+ }
old->it_value = ktime_to_timespec(timerfd_get_remaining(ctx));
old->it_interval = ktime_to_timespec(ctx->tintv);
@@ -345,9 +421,18 @@ static int do_timerfd_gettime(int ufd, struct itimerspec *t)
spin_lock_irq(&ctx->wqh.lock);
if (ctx->expired && ctx->tintv.tv64) {
ctx->expired = 0;
- ctx->ticks +=
- hrtimer_forward_now(&ctx->tmr, ctx->tintv) - 1;
- hrtimer_restart(&ctx->tmr);
+
+ if (isalarm(ctx)) {
+ ctx->ticks +=
+ alarm_forward_now(
+ &ctx->t.alarm, ctx->tintv) - 1;
+ alarm_restart(&ctx->t.alarm);
+ } else {
+ ctx->ticks +=
+ hrtimer_forward_now(&ctx->t.tmr, ctx->tintv)
+ - 1;
+ hrtimer_restart(&ctx->t.tmr);
+ }
}
t->it_value = ktime_to_timespec(timerfd_get_remaining(ctx));
t->it_interval = ktime_to_timespec(ctx->tintv);
--
1.8.2.1
On 05/15/2013 02:38 PM, Todd Poynor wrote:
> Add functions needed for hooking up alarmtimer to timerfd:
>
> * alarm_restart: Similar to hrtimer_restart, restart an alarmtimer after
> the expires time has already been updated (as with alarm_forward).
>
> * alarm_forward_now: Similar to hrtimer_forward_now, move the expires
> time forward to an interval from the current time of the associated clock.
>
> * alarm_start_relative: Start an alarmtimer with an expires time relative to
> the current time of the associated clock.
>
> * alarm_expires_remaining: Similar to hrtimer_expires_remaining, return the
> amount of time remaining until alarm expiry.
>
> Signed-off-by: Todd Poynor <[email protected]>
Acked-by: John Stultz <[email protected]>
I'll queue this in my tree for 3.11, but I need to sort out which path
the timerfd code needs to go upstream.
thanks
-john
On 05/15/2013 02:38 PM, Todd Poynor wrote:
> Add support for clocks CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM,
> thereby enabling wakeup alarm timers via file descriptors.
>
> Signed-off-by: Todd Poynor <[email protected]>
This all looks great to me and has been on my own todo list for awhile.
As I said, I'll queue the alarmtimer changes, and if I can get some acks
from the fs folks, I'd be happy to queue the timerfd changes.
thanks
-john
On 05/15/2013 02:51 PM, John Stultz wrote:
> On 05/15/2013 02:38 PM, Todd Poynor wrote:
>> Add support for clocks CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM,
>> thereby enabling wakeup alarm timers via file descriptors.
>>
>> Signed-off-by: Todd Poynor <[email protected]>
>
> This all looks great to me and has been on my own todo list for awhile.
>
> As I said, I'll queue the alarmtimer changes, and if I can get some
> acks from the fs folks, I'd be happy to queue the timerfd changes.
>
Ping? Any fsdevel folks mind taking a look at this?
Or maybe to turn this around, are there any objections to this change
going in via tip/timers/core?
thanks
-john