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@@ -25,13 +25,15 @@ struct timerfd_ctx {
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struct hrtimer tmr;
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ktime_t tintv;
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wait_queue_head_t wqh;
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+ u64 ticks;
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int expired;
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+ int clockid;
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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 read.
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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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{
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@@ -40,13 +42,24 @@ static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
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spin_lock_irqsave(&ctx->wqh.lock, flags);
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ctx->expired = 1;
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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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return HRTIMER_NORESTART;
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}
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-static void timerfd_setup(struct timerfd_ctx *ctx, int clockid, int flags,
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+static ktime_t timerfd_get_remaining(struct timerfd_ctx *ctx)
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+{
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+ ktime_t now, remaining;
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+
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+ now = ctx->tmr.base->get_time();
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+ remaining = ktime_sub(ctx->tmr.expires, now);
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+
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+ return remaining.tv64 < 0 ? ktime_set(0, 0): remaining;
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+}
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+
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+static void timerfd_setup(struct timerfd_ctx *ctx, int flags,
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const struct itimerspec *ktmr)
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{
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enum hrtimer_mode htmode;
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@@ -57,8 +70,9 @@ static void timerfd_setup(struct timerfd_ctx *ctx, int clockid, int flags,
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texp = timespec_to_ktime(ktmr->it_value);
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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_init(&ctx->tmr, ctx->clockid, htmode);
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ctx->tmr.expires = texp;
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ctx->tmr.function = timerfd_tmrproc;
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if (texp.tv64 != 0)
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@@ -83,7 +97,7 @@ static unsigned int timerfd_poll(struct file *file, poll_table *wait)
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poll_wait(file, &ctx->wqh, wait);
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spin_lock_irqsave(&ctx->wqh.lock, flags);
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- if (ctx->expired)
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+ if (ctx->ticks)
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events |= POLLIN;
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spin_unlock_irqrestore(&ctx->wqh.lock, flags);
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@@ -102,11 +116,11 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
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return -EINVAL;
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spin_lock_irq(&ctx->wqh.lock);
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res = -EAGAIN;
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- if (!ctx->expired && !(file->f_flags & O_NONBLOCK)) {
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+ if (!ctx->ticks && !(file->f_flags & O_NONBLOCK)) {
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__add_wait_queue(&ctx->wqh, &wait);
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for (res = 0;;) {
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set_current_state(TASK_INTERRUPTIBLE);
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- if (ctx->expired) {
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+ if (ctx->ticks) {
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res = 0;
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break;
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}
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@@ -121,22 +135,21 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
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__remove_wait_queue(&ctx->wqh, &wait);
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__set_current_state(TASK_RUNNING);
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}
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- if (ctx->expired) {
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- ctx->expired = 0;
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- if (ctx->tintv.tv64 != 0) {
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+ if (ctx->ticks) {
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+ ticks = ctx->ticks;
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+ if (ctx->expired && ctx->tintv.tv64) {
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/*
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* If tintv.tv64 != 0, this is a periodic timer that
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* needs to be re-armed. We avoid doing it in the timer
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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 = (u64)
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- hrtimer_forward(&ctx->tmr,
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- hrtimer_cb_get_time(&ctx->tmr),
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- ctx->tintv);
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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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- } else
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- ticks = 1;
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+ }
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+ ctx->expired = 0;
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+ ctx->ticks = 0;
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}
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spin_unlock_irq(&ctx->wqh.lock);
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if (ticks)
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@@ -150,76 +163,132 @@ static const struct file_operations timerfd_fops = {
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.read = timerfd_read,
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};
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-asmlinkage long sys_timerfd(int ufd, int clockid, int flags,
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- const struct itimerspec __user *utmr)
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+static struct file *timerfd_fget(int fd)
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+{
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+ struct file *file;
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+
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+ file = fget(fd);
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+ if (!file)
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+ return ERR_PTR(-EBADF);
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+ if (file->f_op != &timerfd_fops) {
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+ fput(file);
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+ return ERR_PTR(-EINVAL);
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+ }
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+
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+ return file;
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+}
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+
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+asmlinkage long sys_timerfd_create(int clockid, int flags)
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{
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- int error;
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+ int error, ufd;
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struct timerfd_ctx *ctx;
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struct file *file;
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struct inode *inode;
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- struct itimerspec ktmr;
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-
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- if (copy_from_user(&ktmr, utmr, sizeof(ktmr)))
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- return -EFAULT;
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+ if (flags)
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+ return -EINVAL;
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if (clockid != CLOCK_MONOTONIC &&
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clockid != CLOCK_REALTIME)
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return -EINVAL;
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+
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+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
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+ if (!ctx)
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+ return -ENOMEM;
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+
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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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+
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+ error = anon_inode_getfd(&ufd, &inode, &file, "[timerfd]",
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+ &timerfd_fops, ctx);
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+ if (error) {
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+ kfree(ctx);
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+ return error;
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+ }
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+
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+ return ufd;
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+}
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+
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+asmlinkage long sys_timerfd_settime(int ufd, int flags,
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+ const struct itimerspec __user *utmr,
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+ struct itimerspec __user *otmr)
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+{
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+ struct file *file;
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+ struct timerfd_ctx *ctx;
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+ struct itimerspec ktmr, kotmr;
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+
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+ if (copy_from_user(&ktmr, utmr, sizeof(ktmr)))
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+ return -EFAULT;
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+
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if (!timespec_valid(&ktmr.it_value) ||
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!timespec_valid(&ktmr.it_interval))
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return -EINVAL;
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- if (ufd == -1) {
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- ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
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- if (!ctx)
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- return -ENOMEM;
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-
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- init_waitqueue_head(&ctx->wqh);
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-
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- timerfd_setup(ctx, clockid, flags, &ktmr);
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-
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- /*
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- * When we call this, the initialization must be complete, since
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- * anon_inode_getfd() will install the fd.
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- */
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- error = anon_inode_getfd(&ufd, &inode, &file, "[timerfd]",
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- &timerfd_fops, ctx);
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- if (error)
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- goto err_tmrcancel;
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- } else {
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- file = fget(ufd);
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- if (!file)
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- return -EBADF;
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- ctx = file->private_data;
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- if (file->f_op != &timerfd_fops) {
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- fput(file);
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- return -EINVAL;
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- }
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- /*
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- * We need to stop the existing timer before reprogramming
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- * it to the new values.
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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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- spin_unlock_irq(&ctx->wqh.lock);
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- cpu_relax();
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- }
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- /*
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- * Re-program the timer to the new value ...
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- */
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- timerfd_setup(ctx, clockid, flags, &ktmr);
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+ file = timerfd_fget(ufd);
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+ if (IS_ERR(file))
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+ return PTR_ERR(file);
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+ ctx = file->private_data;
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+ /*
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+ * We need to stop the existing timer before reprogramming
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+ * it to the new values.
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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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spin_unlock_irq(&ctx->wqh.lock);
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- fput(file);
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+ cpu_relax();
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}
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- return ufd;
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+ /*
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+ * If the timer is expired and it's periodic, we need to advance it
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+ * because the caller may want to know the previous expiration time.
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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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-err_tmrcancel:
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- hrtimer_cancel(&ctx->tmr);
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- kfree(ctx);
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- return error;
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+ kotmr.it_value = ktime_to_timespec(timerfd_get_remaining(ctx));
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+ kotmr.it_interval = ktime_to_timespec(ctx->tintv);
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+
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+ /*
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+ * Re-program the timer to the new value ...
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+ */
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+ timerfd_setup(ctx, flags, &ktmr);
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+
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+ spin_unlock_irq(&ctx->wqh.lock);
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+ fput(file);
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+ if (otmr && copy_to_user(otmr, &kotmr, sizeof(kotmr)))
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+ return -EFAULT;
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+
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+ return 0;
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+}
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+
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+asmlinkage long sys_timerfd_gettime(int ufd, struct itimerspec __user *otmr)
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+{
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+ struct file *file;
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+ struct timerfd_ctx *ctx;
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+ struct itimerspec kotmr;
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+
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+ file = timerfd_fget(ufd);
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+ if (IS_ERR(file))
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+ return PTR_ERR(file);
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+ ctx = file->private_data;
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+
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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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+ }
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+ kotmr.it_value = ktime_to_timespec(timerfd_get_remaining(ctx));
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+ kotmr.it_interval = ktime_to_timespec(ctx->tintv);
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+ spin_unlock_irq(&ctx->wqh.lock);
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+ fput(file);
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+
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+ return copy_to_user(otmr, &kotmr, sizeof(kotmr)) ? -EFAULT: 0;
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}
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Davide Libenzi