This is the new timerfd API as it is implemented by the following patch:
int timerfd_create(int clockid);
int timerfd_settime(int ufd, int flags,
const struct itimerspec *utmr,
struct itimerspec *otmr);
int timerfd_gettime(int ufd, struct itimerspec *otmr);
The timerfd_create() API creates an un-programmed timerfd fd. The "clockid"
parameter can be either CLOCK_MONOTONIC or CLOCK_REALTIME.
The timerfd_settime() API give new settings by the timerfd fd, by optionally
retrieving the previous expiration time (in case the "otmr" parameter is not NULL).
The time value specified in "utmr" is absolute, if the TFD_TIMER_ABSTIME bit
is set in the "flags" parameter. Otherwise it's a relative time.
The timerfd_gettime() API returns the next expiration time of the timer, or {0, 0}
if the timerfd has not been set yet.
Like the previous timerfd API implementation, read(2) and poll(2) are supported
(with the same interface).
Here's a simple test program I used to exercise the new timerfd APIs:
http://www.xmailserver.org/timerfd-test2.c
Signed-off-by: Davide Libenzi <[email protected]>
- Davide
---
fs/compat.c | 32 ++++++-
fs/timerfd.c | 197 ++++++++++++++++++++++++++++++-----------------
include/linux/compat.h | 7 +
include/linux/syscalls.h | 7 +
4 files changed, 164 insertions(+), 79 deletions(-)
Index: linux-2.6.mod/fs/timerfd.c
===================================================================
--- linux-2.6.mod.orig/fs/timerfd.c 2007-09-24 12:26:19.000000000 -0700
+++ linux-2.6.mod/fs/timerfd.c 2007-09-24 12:31:22.000000000 -0700
@@ -25,13 +25,15 @@
struct hrtimer tmr;
ktime_t tintv;
wait_queue_head_t wqh;
+ u64 ticks;
int expired;
+ int clockid;
};
/*
* 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 read.
+ * tintv.tv64 != 0) until the timer is accessed.
*/
static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
{
@@ -40,13 +42,14 @@
spin_lock_irqsave(&ctx->wqh.lock, flags);
ctx->expired = 1;
+ ctx->ticks++;
wake_up_locked(&ctx->wqh);
spin_unlock_irqrestore(&ctx->wqh.lock, flags);
return HRTIMER_NORESTART;
}
-static void timerfd_setup(struct timerfd_ctx *ctx, int clockid, int flags,
+static void timerfd_setup(struct timerfd_ctx *ctx, int flags,
const struct itimerspec *ktmr)
{
enum hrtimer_mode htmode;
@@ -57,8 +60,9 @@
texp = timespec_to_ktime(ktmr->it_value);
ctx->expired = 0;
+ ctx->ticks = 0;
ctx->tintv = timespec_to_ktime(ktmr->it_interval);
- hrtimer_init(&ctx->tmr, clockid, htmode);
+ hrtimer_init(&ctx->tmr, ctx->clockid, htmode);
ctx->tmr.expires = texp;
ctx->tmr.function = timerfd_tmrproc;
if (texp.tv64 != 0)
@@ -83,7 +87,7 @@
poll_wait(file, &ctx->wqh, wait);
spin_lock_irqsave(&ctx->wqh.lock, flags);
- if (ctx->expired)
+ if (ctx->ticks)
events |= POLLIN;
spin_unlock_irqrestore(&ctx->wqh.lock, flags);
@@ -102,11 +106,11 @@
return -EINVAL;
spin_lock_irq(&ctx->wqh.lock);
res = -EAGAIN;
- if (!ctx->expired && !(file->f_flags & O_NONBLOCK)) {
+ if (!ctx->ticks && !(file->f_flags & O_NONBLOCK)) {
__add_wait_queue(&ctx->wqh, &wait);
for (res = 0;;) {
set_current_state(TASK_INTERRUPTIBLE);
- if (ctx->expired) {
+ if (ctx->ticks) {
res = 0;
break;
}
@@ -121,22 +125,21 @@
__remove_wait_queue(&ctx->wqh, &wait);
__set_current_state(TASK_RUNNING);
}
- if (ctx->expired) {
- ctx->expired = 0;
- if (ctx->tintv.tv64 != 0) {
+ if (ctx->ticks) {
+ ticks = ctx->ticks;
+ if (ctx->expired && ctx->tintv.tv64) {
/*
* If tintv.tv64 != 0, this is a periodic timer that
* needs to be re-armed. We avoid doing it in the timer
* callback to avoid DoS attacks specifying a very
* short timer period.
*/
- ticks = (u64)
- hrtimer_forward(&ctx->tmr,
- hrtimer_cb_get_time(&ctx->tmr),
- ctx->tintv);
+ ticks += (u64) hrtimer_forward_now(&ctx->tmr,
+ ctx->tintv) - 1;
hrtimer_restart(&ctx->tmr);
- } else
- ticks = 1;
+ }
+ ctx->expired = 0;
+ ctx->ticks = 0;
}
spin_unlock_irq(&ctx->wqh.lock);
if (ticks)
@@ -150,76 +153,130 @@
.read = timerfd_read,
};
-asmlinkage long sys_timerfd(int ufd, int clockid, int flags,
- const struct itimerspec __user *utmr)
+static struct file *timerfd_fget(int fd)
+{
+ struct file *file;
+
+ file = fget(fd);
+ if (!file)
+ return ERR_PTR(-EBADF);
+ if (file->f_op != &timerfd_fops) {
+ fput(file);
+ return ERR_PTR(-EINVAL);
+ }
+
+ return file;
+}
+
+asmlinkage long sys_timerfd_create(int clockid)
{
- int error;
+ int error, ufd;
struct timerfd_ctx *ctx;
struct file *file;
struct inode *inode;
- struct itimerspec ktmr;
-
- if (copy_from_user(&ktmr, utmr, sizeof(ktmr)))
- return -EFAULT;
if (clockid != CLOCK_MONOTONIC &&
clockid != CLOCK_REALTIME)
return -EINVAL;
+
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+
+ init_waitqueue_head(&ctx->wqh);
+ ctx->clockid = clockid;
+ hrtimer_init(&ctx->tmr, clockid, HRTIMER_MODE_ABS);
+
+ error = anon_inode_getfd(&ufd, &inode, &file, "[timerfd]",
+ &timerfd_fops, ctx);
+ if (error) {
+ kfree(ctx);
+ return error;
+ }
+
+ return ufd;
+}
+
+asmlinkage long sys_timerfd_settime(int ufd, int flags,
+ const struct itimerspec __user *utmr,
+ struct itimerspec __user *otmr)
+{
+ struct file *file;
+ struct timerfd_ctx *ctx;
+ struct itimerspec ktmr, kotmr;
+
+ if (copy_from_user(&ktmr, utmr, sizeof(ktmr)))
+ return -EFAULT;
+
if (!timespec_valid(&ktmr.it_value) ||
!timespec_valid(&ktmr.it_interval))
return -EINVAL;
- if (ufd == -1) {
- ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
- if (!ctx)
- return -ENOMEM;
-
- init_waitqueue_head(&ctx->wqh);
-
- timerfd_setup(ctx, clockid, flags, &ktmr);
-
- /*
- * When we call this, the initialization must be complete, since
- * anon_inode_getfd() will install the fd.
- */
- error = anon_inode_getfd(&ufd, &inode, &file, "[timerfd]",
- &timerfd_fops, ctx);
- if (error)
- goto err_tmrcancel;
- } else {
- file = fget(ufd);
- if (!file)
- return -EBADF;
- ctx = file->private_data;
- if (file->f_op != &timerfd_fops) {
- fput(file);
- return -EINVAL;
- }
- /*
- * We need to stop the existing timer before reprogramming
- * it to the new values.
- */
- for (;;) {
- spin_lock_irq(&ctx->wqh.lock);
- if (hrtimer_try_to_cancel(&ctx->tmr) >= 0)
- break;
- spin_unlock_irq(&ctx->wqh.lock);
- cpu_relax();
- }
- /*
- * Re-program the timer to the new value ...
- */
- timerfd_setup(ctx, clockid, flags, &ktmr);
-
+ file = timerfd_fget(ufd);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+ ctx = file->private_data;
+
+ /*
+ * We need to stop the existing timer before reprogramming
+ * it to the new values.
+ */
+ for (;;) {
+ spin_lock_irq(&ctx->wqh.lock);
+ if (hrtimer_try_to_cancel(&ctx->tmr) >= 0)
+ break;
spin_unlock_irq(&ctx->wqh.lock);
- fput(file);
+ cpu_relax();
}
- return ufd;
+ /*
+ * If the timer is expired and it's periodic, we need to advance it
+ * because the caller may want to know the previous expiration time.
+ * 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);
+
+ kotmr.it_value = ktime_to_timespec(ctx->tmr.expires);
+ kotmr.it_interval = ktime_to_timespec(ctx->tintv);
+
+ /*
+ * Re-program the timer to the new value ...
+ */
+ timerfd_setup(ctx, flags, &ktmr);
-err_tmrcancel:
- hrtimer_cancel(&ctx->tmr);
- kfree(ctx);
- return error;
+ spin_unlock_irq(&ctx->wqh.lock);
+ fput(file);
+ if (otmr && copy_to_user(otmr, &kotmr, sizeof(kotmr)))
+ return -EFAULT;
+
+ return 0;
+}
+
+asmlinkage long sys_timerfd_gettime(int ufd, struct itimerspec __user *otmr)
+{
+ struct file *file;
+ struct timerfd_ctx *ctx;
+ struct itimerspec kotmr;
+
+ file = timerfd_fget(ufd);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+ ctx = file->private_data;
+
+ spin_lock_irq(&ctx->wqh.lock);
+ if (ctx->expired && ctx->tintv.tv64) {
+ ctx->expired = 0;
+ ctx->ticks += (u64)
+ hrtimer_forward_now(&ctx->tmr, ctx->tintv) - 1;
+ hrtimer_restart(&ctx->tmr);
+ }
+ kotmr.it_value = ktime_to_timespec(ctx->tmr.expires);
+ kotmr.it_interval = ktime_to_timespec(ctx->tintv);
+ spin_unlock_irq(&ctx->wqh.lock);
+ fput(file);
+
+ return copy_to_user(otmr, &kotmr, sizeof(kotmr)) ? -EFAULT: 0;
}
Index: linux-2.6.mod/include/linux/syscalls.h
===================================================================
--- linux-2.6.mod.orig/include/linux/syscalls.h 2007-09-24 12:26:19.000000000 -0700
+++ linux-2.6.mod/include/linux/syscalls.h 2007-09-24 12:30:17.000000000 -0700
@@ -607,8 +607,11 @@
size_t len);
asmlinkage long sys_getcpu(unsigned __user *cpu, unsigned __user *node, struct getcpu_cache __user *cache);
asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemask);
-asmlinkage long sys_timerfd(int ufd, int clockid, int flags,
- const struct itimerspec __user *utmr);
+asmlinkage long sys_timerfd_create(int clockid);
+asmlinkage long sys_timerfd_settime(int ufd, int flags,
+ const struct itimerspec __user *utmr,
+ struct itimerspec __user *otmr);
+asmlinkage long sys_timerfd_gettime(int ufd, struct itimerspec __user *otmr);
asmlinkage long sys_eventfd(unsigned int count);
asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len);
Index: linux-2.6.mod/fs/compat.c
===================================================================
--- linux-2.6.mod.orig/fs/compat.c 2007-09-24 12:26:19.000000000 -0700
+++ linux-2.6.mod/fs/compat.c 2007-09-24 12:30:17.000000000 -0700
@@ -2210,19 +2210,41 @@
#ifdef CONFIG_TIMERFD
-asmlinkage long compat_sys_timerfd(int ufd, int clockid, int flags,
- const struct compat_itimerspec __user *utmr)
+asmlinkage long compat_sys_timerfd_settime(int ufd, int flags,
+ const struct compat_itimerspec __user *utmr,
+ struct compat_itimerspec __user *otmr)
{
+ int error;
struct itimerspec t;
struct itimerspec __user *ut;
if (get_compat_itimerspec(&t, utmr))
return -EFAULT;
- ut = compat_alloc_user_space(sizeof(*ut));
- if (copy_to_user(ut, &t, sizeof(t)))
+ ut = compat_alloc_user_space(2 * sizeof(struct itimerspec));
+ if (copy_to_user(&ut[0], &t, sizeof(t)))
return -EFAULT;
+ error = sys_timerfd_settime(ufd, flags, &ut[0], &ut[1]);
+ if (!error && otmr)
+ error = (copy_from_user(&t, &ut[1], sizeof(struct itimerspec)) ||
+ put_compat_itimerspec(otmr, &t)) ? -EFAULT: 0;
- return sys_timerfd(ufd, clockid, flags, ut);
+ return error;
+}
+
+asmlinkage long compat_sys_timerfd_gettime(int ufd,
+ struct compat_itimerspec __user *otmr)
+{
+ int error;
+ struct itimerspec t;
+ struct itimerspec __user *ut;
+
+ ut = compat_alloc_user_space(sizeof(struct itimerspec));
+ error = sys_timerfd_gettime(ufd, ut);
+ if (!error)
+ error = (copy_from_user(&t, ut, sizeof(struct itimerspec)) ||
+ put_compat_itimerspec(otmr, &t)) ? -EFAULT: 0;
+
+ return error;
}
#endif /* CONFIG_TIMERFD */
Index: linux-2.6.mod/include/linux/compat.h
===================================================================
--- linux-2.6.mod.orig/include/linux/compat.h 2007-09-24 12:26:19.000000000 -0700
+++ linux-2.6.mod/include/linux/compat.h 2007-09-24 12:30:17.000000000 -0700
@@ -264,8 +264,11 @@
asmlinkage long compat_sys_signalfd(int ufd,
const compat_sigset_t __user *sigmask,
compat_size_t sigsetsize);
-asmlinkage long compat_sys_timerfd(int ufd, int clockid, int flags,
- const struct compat_itimerspec __user *utmr);
+asmlinkage long compat_sys_timerfd_settime(int ufd, int flags,
+ const struct compat_itimerspec __user *utmr,
+ struct compat_itimerspec __user *otmr);
+asmlinkage long compat_sys_timerfd_gettime(int ufd,
+ struct compat_itimerspec __user *otmr);
#endif /* CONFIG_COMPAT */
#endif /* _LINUX_COMPAT_H */
Davide Libenzi wrote:
> This is the new timerfd API as it is implemented by the following patch:
>
> int timerfd_create(int clockid);
> int timerfd_settime(int ufd, int flags,
> const struct itimerspec *utmr,
> struct itimerspec *otmr);
> int timerfd_gettime(int ufd, struct itimerspec *otmr);
>
> The timerfd_create() API creates an un-programmed timerfd fd. The "clockid"
> parameter can be either CLOCK_MONOTONIC or CLOCK_REALTIME.
> The timerfd_settime() API give new settings by the timerfd fd, by optionally
> retrieving the previous expiration time (in case the "otmr" parameter is not NULL).
> The time value specified in "utmr" is absolute, if the TFD_TIMER_ABSTIME bit
> is set in the "flags" parameter. Otherwise it's a relative time.
> The timerfd_gettime() API returns the next expiration time of the timer, or {0, 0}
> if the timerfd has not been set yet.
> Like the previous timerfd API implementation, read(2) and poll(2) are supported
> (with the same interface).
> Here's a simple test program I used to exercise the new timerfd APIs:
>
> http://www.xmailserver.org/timerfd-test2.c
>
>
>
> Signed-off-by: Davide Libenzi <[email protected]>
>
>
> - Davide
>
>
> ---
> fs/compat.c | 32 ++++++-
> fs/timerfd.c | 197 ++++++++++++++++++++++++++++++-----------------
> include/linux/compat.h | 7 +
> include/linux/syscalls.h | 7 +
> 4 files changed, 164 insertions(+), 79 deletions(-)
>
> Index: linux-2.6.mod/fs/timerfd.c
> ===================================================================
> --- linux-2.6.mod.orig/fs/timerfd.c 2007-09-24 12:26:19.000000000 -0700
> +++ linux-2.6.mod/fs/timerfd.c 2007-09-24 12:31:22.000000000 -0700
> @@ -25,13 +25,15 @@
> struct hrtimer tmr;
> ktime_t tintv;
> wait_queue_head_t wqh;
> + u64 ticks;
> int expired;
> + int clockid;
> };
>
> /*
> * 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 read.
> + * tintv.tv64 != 0) until the timer is accessed.
> */
> static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
> {
> @@ -40,13 +42,14 @@
>
> spin_lock_irqsave(&ctx->wqh.lock, flags);
> ctx->expired = 1;
> + ctx->ticks++;
> wake_up_locked(&ctx->wqh);
> spin_unlock_irqrestore(&ctx->wqh.lock, flags);
>
> return HRTIMER_NORESTART;
> }
>
> -static void timerfd_setup(struct timerfd_ctx *ctx, int clockid, int flags,
> +static void timerfd_setup(struct timerfd_ctx *ctx, int flags,
> const struct itimerspec *ktmr)
> {
> enum hrtimer_mode htmode;
> @@ -57,8 +60,9 @@
>
> texp = timespec_to_ktime(ktmr->it_value);
> ctx->expired = 0;
> + ctx->ticks = 0;
> ctx->tintv = timespec_to_ktime(ktmr->it_interval);
> - hrtimer_init(&ctx->tmr, clockid, htmode);
> + hrtimer_init(&ctx->tmr, ctx->clockid, htmode);
> ctx->tmr.expires = texp;
> ctx->tmr.function = timerfd_tmrproc;
> if (texp.tv64 != 0)
> @@ -83,7 +87,7 @@
> poll_wait(file, &ctx->wqh, wait);
>
> spin_lock_irqsave(&ctx->wqh.lock, flags);
> - if (ctx->expired)
> + if (ctx->ticks)
> events |= POLLIN;
> spin_unlock_irqrestore(&ctx->wqh.lock, flags);
>
> @@ -102,11 +106,11 @@
> return -EINVAL;
> spin_lock_irq(&ctx->wqh.lock);
> res = -EAGAIN;
> - if (!ctx->expired && !(file->f_flags & O_NONBLOCK)) {
> + if (!ctx->ticks && !(file->f_flags & O_NONBLOCK)) {
> __add_wait_queue(&ctx->wqh, &wait);
> for (res = 0;;) {
> set_current_state(TASK_INTERRUPTIBLE);
> - if (ctx->expired) {
> + if (ctx->ticks) {
> res = 0;
> break;
> }
> @@ -121,22 +125,21 @@
> __remove_wait_queue(&ctx->wqh, &wait);
> __set_current_state(TASK_RUNNING);
> }
> - if (ctx->expired) {
> - ctx->expired = 0;
> - if (ctx->tintv.tv64 != 0) {
> + if (ctx->ticks) {
> + ticks = ctx->ticks;
> + if (ctx->expired && ctx->tintv.tv64) {
> /*
> * If tintv.tv64 != 0, this is a periodic timer that
> * needs to be re-armed. We avoid doing it in the timer
> * callback to avoid DoS attacks specifying a very
> * short timer period.
> */
> - ticks = (u64)
> - hrtimer_forward(&ctx->tmr,
> - hrtimer_cb_get_time(&ctx->tmr),
> - ctx->tintv);
> + ticks += (u64) hrtimer_forward_now(&ctx->tmr,
> + ctx->tintv) - 1;
> hrtimer_restart(&ctx->tmr);
> - } else
> - ticks = 1;
> + }
> + ctx->expired = 0;
> + ctx->ticks = 0;
> }
> spin_unlock_irq(&ctx->wqh.lock);
> if (ticks)
> @@ -150,76 +153,130 @@
> .read = timerfd_read,
> };
>
> -asmlinkage long sys_timerfd(int ufd, int clockid, int flags,
> - const struct itimerspec __user *utmr)
> +static struct file *timerfd_fget(int fd)
> +{
> + struct file *file;
> +
> + file = fget(fd);
> + if (!file)
> + return ERR_PTR(-EBADF);
> + if (file->f_op != &timerfd_fops) {
> + fput(file);
> + return ERR_PTR(-EINVAL);
> + }
> +
> + return file;
> +}
> +
> +asmlinkage long sys_timerfd_create(int clockid)
> {
> - int error;
> + int error, ufd;
> struct timerfd_ctx *ctx;
> struct file *file;
> struct inode *inode;
> - struct itimerspec ktmr;
> -
> - if (copy_from_user(&ktmr, utmr, sizeof(ktmr)))
> - return -EFAULT;
>
> if (clockid != CLOCK_MONOTONIC &&
> clockid != CLOCK_REALTIME)
> return -EINVAL;
> +
> + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> + if (!ctx)
> + return -ENOMEM;
> +
> + init_waitqueue_head(&ctx->wqh);
> + ctx->clockid = clockid;
> + hrtimer_init(&ctx->tmr, clockid, HRTIMER_MODE_ABS);
> +
> + error = anon_inode_getfd(&ufd, &inode, &file, "[timerfd]",
> + &timerfd_fops, ctx);
> + if (error) {
> + kfree(ctx);
> + return error;
> + }
> +
> + return ufd;
> +}
> +
> +asmlinkage long sys_timerfd_settime(int ufd, int flags,
> + const struct itimerspec __user *utmr,
> + struct itimerspec __user *otmr)
> +{
> + struct file *file;
> + struct timerfd_ctx *ctx;
> + struct itimerspec ktmr, kotmr;
> +
> + if (copy_from_user(&ktmr, utmr, sizeof(ktmr)))
> + return -EFAULT;
> +
> if (!timespec_valid(&ktmr.it_value) ||
> !timespec_valid(&ktmr.it_interval))
> return -EINVAL;
>
> - if (ufd == -1) {
> - ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
> - if (!ctx)
> - return -ENOMEM;
> -
> - init_waitqueue_head(&ctx->wqh);
> -
> - timerfd_setup(ctx, clockid, flags, &ktmr);
> -
> - /*
> - * When we call this, the initialization must be complete, since
> - * anon_inode_getfd() will install the fd.
> - */
> - error = anon_inode_getfd(&ufd, &inode, &file, "[timerfd]",
> - &timerfd_fops, ctx);
> - if (error)
> - goto err_tmrcancel;
> - } else {
> - file = fget(ufd);
> - if (!file)
> - return -EBADF;
> - ctx = file->private_data;
> - if (file->f_op != &timerfd_fops) {
> - fput(file);
> - return -EINVAL;
> - }
> - /*
> - * We need to stop the existing timer before reprogramming
> - * it to the new values.
> - */
> - for (;;) {
> - spin_lock_irq(&ctx->wqh.lock);
> - if (hrtimer_try_to_cancel(&ctx->tmr) >= 0)
> - break;
> - spin_unlock_irq(&ctx->wqh.lock);
> - cpu_relax();
> - }
> - /*
> - * Re-program the timer to the new value ...
> - */
> - timerfd_setup(ctx, clockid, flags, &ktmr);
> -
> + file = timerfd_fget(ufd);
> + if (IS_ERR(file))
> + return PTR_ERR(file);
> + ctx = file->private_data;
> +
> + /*
> + * We need to stop the existing timer before reprogramming
> + * it to the new values.
> + */
> + for (;;) {
> + spin_lock_irq(&ctx->wqh.lock);
> + if (hrtimer_try_to_cancel(&ctx->tmr) >= 0)
> + break;
> spin_unlock_irq(&ctx->wqh.lock);
> - fput(file);
> + cpu_relax();
> }
>
> - return ufd;
> + /*
> + * If the timer is expired and it's periodic, we need to advance it
> + * because the caller may want to know the previous expiration time.
> + * 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);
> +
> + kotmr.it_value = ktime_to_timespec(ctx->tmr.expires);
> + kotmr.it_interval = ktime_to_timespec(ctx->tintv);
> +
> + /*
> + * Re-program the timer to the new value ...
> + */
> + timerfd_setup(ctx, flags, &ktmr);
>
> -err_tmrcancel:
> - hrtimer_cancel(&ctx->tmr);
> - kfree(ctx);
> - return error;
> + spin_unlock_irq(&ctx->wqh.lock);
> + fput(file);
> + if (otmr && copy_to_user(otmr, &kotmr, sizeof(kotmr)))
> + return -EFAULT;
> +
> + return 0;
> +}
> +
> +asmlinkage long sys_timerfd_gettime(int ufd, struct itimerspec __user *otmr)
> +{
> + struct file *file;
> + struct timerfd_ctx *ctx;
> + struct itimerspec kotmr;
> +
> + file = timerfd_fget(ufd);
> + if (IS_ERR(file))
> + return PTR_ERR(file);
> + ctx = file->private_data;
> +
> + spin_lock_irq(&ctx->wqh.lock);
> + if (ctx->expired && ctx->tintv.tv64) {
> + ctx->expired = 0;
> + ctx->ticks += (u64)
> + hrtimer_forward_now(&ctx->tmr, ctx->tintv) - 1;
> + hrtimer_restart(&ctx->tmr);
> + }
> + kotmr.it_value = ktime_to_timespec(ctx->tmr.expires);
> + kotmr.it_interval = ktime_to_timespec(ctx->tintv);
> + spin_unlock_irq(&ctx->wqh.lock);
> + fput(file);
> +
> + return copy_to_user(otmr, &kotmr, sizeof(kotmr)) ? -EFAULT: 0;
> }
>
> Index: linux-2.6.mod/include/linux/syscalls.h
> ===================================================================
> --- linux-2.6.mod.orig/include/linux/syscalls.h 2007-09-24 12:26:19.000000000 -0700
> +++ linux-2.6.mod/include/linux/syscalls.h 2007-09-24 12:30:17.000000000 -0700
> @@ -607,8 +607,11 @@
> size_t len);
> asmlinkage long sys_getcpu(unsigned __user *cpu, unsigned __user *node, struct getcpu_cache __user *cache);
> asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemask);
> -asmlinkage long sys_timerfd(int ufd, int clockid, int flags,
> - const struct itimerspec __user *utmr);
> +asmlinkage long sys_timerfd_create(int clockid);
> +asmlinkage long sys_timerfd_settime(int ufd, int flags,
> + const struct itimerspec __user *utmr,
> + struct itimerspec __user *otmr);
> +asmlinkage long sys_timerfd_gettime(int ufd, struct itimerspec __user *otmr);
> asmlinkage long sys_eventfd(unsigned int count);
> asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len);
>
> Index: linux-2.6.mod/fs/compat.c
> ===================================================================
> --- linux-2.6.mod.orig/fs/compat.c 2007-09-24 12:26:19.000000000 -0700
> +++ linux-2.6.mod/fs/compat.c 2007-09-24 12:30:17.000000000 -0700
> @@ -2210,19 +2210,41 @@
>
> #ifdef CONFIG_TIMERFD
>
> -asmlinkage long compat_sys_timerfd(int ufd, int clockid, int flags,
> - const struct compat_itimerspec __user *utmr)
> +asmlinkage long compat_sys_timerfd_settime(int ufd, int flags,
> + const struct compat_itimerspec __user *utmr,
> + struct compat_itimerspec __user *otmr)
> {
> + int error;
> struct itimerspec t;
> struct itimerspec __user *ut;
>
> if (get_compat_itimerspec(&t, utmr))
> return -EFAULT;
> - ut = compat_alloc_user_space(sizeof(*ut));
> - if (copy_to_user(ut, &t, sizeof(t)))
> + ut = compat_alloc_user_space(2 * sizeof(struct itimerspec));
> + if (copy_to_user(&ut[0], &t, sizeof(t)))
> return -EFAULT;
> + error = sys_timerfd_settime(ufd, flags, &ut[0], &ut[1]);
> + if (!error && otmr)
> + error = (copy_from_user(&t, &ut[1], sizeof(struct itimerspec)) ||
> + put_compat_itimerspec(otmr, &t)) ? -EFAULT: 0;
I guess this should work as well (and looks clearer):
if (!error && otmr)
if ( copy_from_user(&t, &ut[1], sizeof(struct itimerspec)) ||
put_compat_itimerspec(otmr, &t))
error = -EFAULT;
>
> - return sys_timerfd(ufd, clockid, flags, ut);
> + return error;
> +}
> +
> +asmlinkage long compat_sys_timerfd_gettime(int ufd,
> + struct compat_itimerspec __user *otmr)
> +{
> + int error;
> + struct itimerspec t;
> + struct itimerspec __user *ut;
> +
> + ut = compat_alloc_user_space(sizeof(struct itimerspec));
> + error = sys_timerfd_gettime(ufd, ut);
> + if (!error)
> + error = (copy_from_user(&t, ut, sizeof(struct itimerspec)) ||
> + put_compat_itimerspec(otmr, &t)) ? -EFAULT: 0;
or:
if (!error)
if ( copy_from_user(&t, &ut, sizeof(struct itimerspec)) ||
put_compat_itimerspec(otmr, &t))
error = -EFAULT;
> +
> + return error;
> }
>
> #endif /* CONFIG_TIMERFD */
> Index: linux-2.6.mod/include/linux/compat.h
> ===================================================================
> --- linux-2.6.mod.orig/include/linux/compat.h 2007-09-24 12:26:19.000000000 -0700
> +++ linux-2.6.mod/include/linux/compat.h 2007-09-24 12:30:17.000000000 -0700
> @@ -264,8 +264,11 @@
> asmlinkage long compat_sys_signalfd(int ufd,
> const compat_sigset_t __user *sigmask,
> compat_size_t sigsetsize);
> -asmlinkage long compat_sys_timerfd(int ufd, int clockid, int flags,
> - const struct compat_itimerspec __user *utmr);
> +asmlinkage long compat_sys_timerfd_settime(int ufd, int flags,
> + const struct compat_itimerspec __user *utmr,
> + struct compat_itimerspec __user *otmr);
> +asmlinkage long compat_sys_timerfd_gettime(int ufd,
> + struct compat_itimerspec __user *otmr);
>
> #endif /* CONFIG_COMPAT */
> #endif /* _LINUX_COMPAT_H */
>
> -
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> Please read the FAQ at http://www.tux.org/lkml/
>
One quick question:
> Like the previous timerfd API implementation, read(2) and poll(2) are supported
> (with the same interface).
Looking at that interface, it appears that a process doing a read() on a
timerfd with no timer set will block for a very long time. It's an
obvious "don't do that" situation, but perhaps we could help an
occasional developer get a clue by returning something like -EINVAL when
the timer has not been set?
jon
On Tue, 25 Sep 2007, Jonathan Corbet wrote:
> One quick question:
>
> > Like the previous timerfd API implementation, read(2) and poll(2) are supported
> > (with the same interface).
>
> Looking at that interface, it appears that a process doing a read() on a
> timerfd with no timer set will block for a very long time. It's an
> obvious "don't do that" situation, but perhaps we could help an
> occasional developer get a clue by returning something like -EINVAL when
> the timer has not been set?
That is the same as you try to read once more after an expired timer. You
won't wake up until the next timer event will show up. That is, after at
most TP time for periodic timers, or after the time the next
timerfd_settime() will setup.
I'd like to keep the "timerfd not set yet" and the "timerfd already
expired and not re-armed" acting the same way. That is, wait till next
event happen (unless O_NONBLOCK of course).
- Davide
Davide Libenzi wrote:
> On Tue, 25 Sep 2007, Jonathan Corbet wrote:
>
>> One quick question:
>>
>>> Like the previous timerfd API implementation, read(2) and poll(2) are supported
>>> (with the same interface).
>> Looking at that interface, it appears that a process doing a read() on a
>> timerfd with no timer set will block for a very long time. It's an
>> obvious "don't do that" situation, but perhaps we could help an
>> occasional developer get a clue by returning something like -EINVAL when
>> the timer has not been set?
>
> That is the same as you try to read once more after an expired timer. You
> won't wake up until the next timer event will show up. That is, after at
> most TP time for periodic timers, or after the time the next
> timerfd_settime() will setup.
> I'd like to keep the "timerfd not set yet" and the "timerfd already
> expired and not re-armed" acting the same way. That is, wait till next
> event happen (unless O_NONBLOCK of course).
Yes. The timer_settime() and read() might for example be done in separate
threads, and it would make sense for the read() to block until the timer
has been armed.
Cheers,
Michael
--
Michael Kerrisk
maintainer of Linux man pages Sections 2, 3, 4, 5, and 7
Want to help with man page maintenance? Grab the latest tarball at
http://www.kernel.org/pub/linux/docs/manpages/
read the HOWTOHELP file and grep the source files for 'FIXME'.