2 files changed, 165 insertions, 74 deletions

diff --git a/fs/compat.c b/fs/compat.c
index 5216c3fd7517..69baca5ad608 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -2206,19 +2206,41 @@ asmlinkage long compat_sys_signalfd(int ufd,
 
 #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 error;
+}
+
+asmlinkage long compat_sys_timerfd_gettime(int ufd,
+                                   struct compat_itimerspec __user *otmr)
+{
+        int error;
+        struct itimerspec t;
+        struct itimerspec __user *ut;
 
-        return sys_timerfd(ufd, clockid, flags, 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 */
diff --git a/fs/timerfd.c b/fs/timerfd.c
index 61983f3b107c..10c80b59ec4b 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -25,13 +25,15 @@ struct timerfd_ctx {
         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 +42,24 @@ static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
 
         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 ktime_t timerfd_get_remaining(struct timerfd_ctx *ctx)
+{
+        ktime_t now, remaining;
+
+        now = ctx->tmr.base->get_time();
+        remaining = ktime_sub(ctx->tmr.expires, now);
+
+        return remaining.tv64 < 0 ? ktime_set(0, 0): remaining;
+}
+
+static void timerfd_setup(struct timerfd_ctx *ctx, int flags,
                           const struct itimerspec *ktmr)
 {
         enum hrtimer_mode htmode;
@@ -57,8 +70,9 @@ static void timerfd_setup(struct timerfd_ctx *ctx, int clockid, int flags,
 
         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 +97,7 @@ static unsigned int timerfd_poll(struct file *file, poll_table *wait)
         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 +116,11 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
                 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 +135,21 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
                 __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 += 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 +163,132 @@ static const struct file_operations timerfd_fops = {
         .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 flags)
 {
-        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 (flags)
+                return -EINVAL;
         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);
 
-err_tmrcancel:
-        hrtimer_cancel(&ctx->tmr);
-        kfree(ctx);
-        return error;
+        kotmr.it_value = ktime_to_timespec(timerfd_get_remaining(ctx));
+        kotmr.it_interval = ktime_to_timespec(ctx->tintv);
+
+        /*
+         * Re-program the timer to the new value ...
+         */
+        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;
+}
+
+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 +=
+                        hrtimer_forward_now(&ctx->tmr, ctx->tintv) - 1;
+                hrtimer_restart(&ctx->tmr);
+        }
+        kotmr.it_value = ktime_to_timespec(timerfd_get_remaining(ctx));
+        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;
 }