v4.19.13 snapshot.
diff --git a/fs/timerfd.c b/fs/timerfd.c
new file mode 100644
index 0000000..d69ad80
--- /dev/null
+++ b/fs/timerfd.c
@@ -0,0 +1,589 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * fs/timerfd.c
+ *
+ * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>
+ *
+ *
+ * Thanks to Thomas Gleixner for code reviews and useful comments.
+ *
+ */
+
+#include <linux/alarmtimer.h>
+#include <linux/file.h>
+#include <linux/poll.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/time.h>
+#include <linux/hrtimer.h>
+#include <linux/anon_inodes.h>
+#include <linux/timerfd.h>
+#include <linux/syscalls.h>
+#include <linux/compat.h>
+#include <linux/rcupdate.h>
+
+struct timerfd_ctx {
+ union {
+ struct hrtimer tmr;
+ struct alarm alarm;
+ } t;
+ ktime_t tintv;
+ ktime_t moffs;
+ wait_queue_head_t wqh;
+ u64 ticks;
+ int clockid;
+ short unsigned expired;
+ short unsigned settime_flags; /* to show in fdinfo */
+ struct rcu_head rcu;
+ struct list_head clist;
+ spinlock_t cancel_lock;
+ bool might_cancel;
+};
+
+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 != 0) until the timer is accessed.
+ */
+static void timerfd_triggered(struct timerfd_ctx *ctx)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&ctx->wqh.lock, flags);
+ ctx->expired = 1;
+ ctx->ticks++;
+ wake_up_locked_poll(&ctx->wqh, EPOLLIN);
+ 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
+ * wake-up requires ctx->ticks to be non zero, therefore we increment
+ * it before calling wake_up_locked().
+ */
+void timerfd_clock_was_set(void)
+{
+ ktime_t moffs = ktime_mono_to_real(0);
+ struct timerfd_ctx *ctx;
+ unsigned long flags;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(ctx, &cancel_list, clist) {
+ if (!ctx->might_cancel)
+ continue;
+ spin_lock_irqsave(&ctx->wqh.lock, flags);
+ if (ctx->moffs != moffs) {
+ ctx->moffs = KTIME_MAX;
+ ctx->ticks++;
+ wake_up_locked_poll(&ctx->wqh, EPOLLIN);
+ }
+ spin_unlock_irqrestore(&ctx->wqh.lock, flags);
+ }
+ rcu_read_unlock();
+}
+
+static void __timerfd_remove_cancel(struct timerfd_ctx *ctx)
+{
+ if (ctx->might_cancel) {
+ ctx->might_cancel = false;
+ spin_lock(&cancel_lock);
+ list_del_rcu(&ctx->clist);
+ spin_unlock(&cancel_lock);
+ }
+}
+
+static void timerfd_remove_cancel(struct timerfd_ctx *ctx)
+{
+ spin_lock(&ctx->cancel_lock);
+ __timerfd_remove_cancel(ctx);
+ spin_unlock(&ctx->cancel_lock);
+}
+
+static bool timerfd_canceled(struct timerfd_ctx *ctx)
+{
+ if (!ctx->might_cancel || ctx->moffs != KTIME_MAX)
+ return false;
+ ctx->moffs = ktime_mono_to_real(0);
+ return true;
+}
+
+static void timerfd_setup_cancel(struct timerfd_ctx *ctx, int flags)
+{
+ spin_lock(&ctx->cancel_lock);
+ 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);
+ list_add_rcu(&ctx->clist, &cancel_list);
+ spin_unlock(&cancel_lock);
+ }
+ } else {
+ __timerfd_remove_cancel(ctx);
+ }
+ spin_unlock(&ctx->cancel_lock);
+}
+
+static ktime_t timerfd_get_remaining(struct timerfd_ctx *ctx)
+{
+ ktime_t remaining;
+
+ if (isalarm(ctx))
+ remaining = alarm_expires_remaining(&ctx->t.alarm);
+ else
+ remaining = hrtimer_expires_remaining_adjusted(&ctx->t.tmr);
+
+ return remaining < 0 ? 0: remaining;
+}
+
+static int timerfd_setup(struct timerfd_ctx *ctx, int flags,
+ const struct itimerspec64 *ktmr)
+{
+ enum hrtimer_mode htmode;
+ ktime_t texp;
+ int clockid = ctx->clockid;
+
+ htmode = (flags & TFD_TIMER_ABSTIME) ?
+ HRTIMER_MODE_ABS: HRTIMER_MODE_REL;
+
+ texp = timespec64_to_ktime(ktmr->it_value);
+ ctx->expired = 0;
+ ctx->ticks = 0;
+ ctx->tintv = timespec64_to_ktime(ktmr->it_interval);
+
+ 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 != 0) {
+ 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;
+ }
+
+ ctx->settime_flags = flags & TFD_SETTIME_FLAGS;
+ return 0;
+}
+
+static int timerfd_release(struct inode *inode, struct file *file)
+{
+ struct timerfd_ctx *ctx = file->private_data;
+
+ timerfd_remove_cancel(ctx);
+
+ if (isalarm(ctx))
+ alarm_cancel(&ctx->t.alarm);
+ else
+ hrtimer_cancel(&ctx->t.tmr);
+ kfree_rcu(ctx, rcu);
+ return 0;
+}
+
+static __poll_t timerfd_poll(struct file *file, poll_table *wait)
+{
+ struct timerfd_ctx *ctx = file->private_data;
+ __poll_t events = 0;
+ unsigned long flags;
+
+ poll_wait(file, &ctx->wqh, wait);
+
+ spin_lock_irqsave(&ctx->wqh.lock, flags);
+ if (ctx->ticks)
+ events |= EPOLLIN;
+ spin_unlock_irqrestore(&ctx->wqh.lock, flags);
+
+ return events;
+}
+
+static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
+ loff_t *ppos)
+{
+ struct timerfd_ctx *ctx = file->private_data;
+ ssize_t res;
+ u64 ticks = 0;
+
+ if (count < sizeof(ticks))
+ return -EINVAL;
+ spin_lock_irq(&ctx->wqh.lock);
+ if (file->f_flags & O_NONBLOCK)
+ res = -EAGAIN;
+ else
+ res = wait_event_interruptible_locked_irq(ctx->wqh, ctx->ticks);
+
+ /*
+ * If clock has changed, we do not care about the
+ * ticks and we do not rearm the timer. Userspace must
+ * reevaluate anyway.
+ */
+ if (timerfd_canceled(ctx)) {
+ ctx->ticks = 0;
+ ctx->expired = 0;
+ res = -ECANCELED;
+ }
+
+ if (ctx->ticks) {
+ ticks = ctx->ticks;
+
+ if (ctx->expired && ctx->tintv) {
+ /*
+ * If tintv != 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.
+ */
+ 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;
+ }
+ spin_unlock_irq(&ctx->wqh.lock);
+ if (ticks)
+ res = put_user(ticks, (u64 __user *) buf) ? -EFAULT: sizeof(ticks);
+ return res;
+}
+
+#ifdef CONFIG_PROC_FS
+static void timerfd_show(struct seq_file *m, struct file *file)
+{
+ struct timerfd_ctx *ctx = file->private_data;
+ struct itimerspec t;
+
+ spin_lock_irq(&ctx->wqh.lock);
+ t.it_value = ktime_to_timespec(timerfd_get_remaining(ctx));
+ t.it_interval = ktime_to_timespec(ctx->tintv);
+ spin_unlock_irq(&ctx->wqh.lock);
+
+ seq_printf(m,
+ "clockid: %d\n"
+ "ticks: %llu\n"
+ "settime flags: 0%o\n"
+ "it_value: (%llu, %llu)\n"
+ "it_interval: (%llu, %llu)\n",
+ ctx->clockid,
+ (unsigned long long)ctx->ticks,
+ ctx->settime_flags,
+ (unsigned long long)t.it_value.tv_sec,
+ (unsigned long long)t.it_value.tv_nsec,
+ (unsigned long long)t.it_interval.tv_sec,
+ (unsigned long long)t.it_interval.tv_nsec);
+}
+#else
+#define timerfd_show NULL
+#endif
+
+#ifdef CONFIG_CHECKPOINT_RESTORE
+static long timerfd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ struct timerfd_ctx *ctx = file->private_data;
+ int ret = 0;
+
+ switch (cmd) {
+ case TFD_IOC_SET_TICKS: {
+ u64 ticks;
+
+ if (copy_from_user(&ticks, (u64 __user *)arg, sizeof(ticks)))
+ return -EFAULT;
+ if (!ticks)
+ return -EINVAL;
+
+ spin_lock_irq(&ctx->wqh.lock);
+ if (!timerfd_canceled(ctx)) {
+ ctx->ticks = ticks;
+ wake_up_locked_poll(&ctx->wqh, EPOLLIN);
+ } else
+ ret = -ECANCELED;
+ spin_unlock_irq(&ctx->wqh.lock);
+ break;
+ }
+ default:
+ ret = -ENOTTY;
+ break;
+ }
+
+ return ret;
+}
+#else
+#define timerfd_ioctl NULL
+#endif
+
+static const struct file_operations timerfd_fops = {
+ .release = timerfd_release,
+ .poll = timerfd_poll,
+ .read = timerfd_read,
+ .llseek = noop_llseek,
+ .show_fdinfo = timerfd_show,
+ .unlocked_ioctl = timerfd_ioctl,
+};
+
+static int timerfd_fget(int fd, struct fd *p)
+{
+ struct fd f = fdget(fd);
+ if (!f.file)
+ return -EBADF;
+ if (f.file->f_op != &timerfd_fops) {
+ fdput(f);
+ return -EINVAL;
+ }
+ *p = f;
+ return 0;
+}
+
+SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
+{
+ int ufd;
+ struct timerfd_ctx *ctx;
+
+ /* Check the TFD_* constants for consistency. */
+ BUILD_BUG_ON(TFD_CLOEXEC != O_CLOEXEC);
+ BUILD_BUG_ON(TFD_NONBLOCK != O_NONBLOCK);
+
+ if ((flags & ~TFD_CREATE_FLAGS) ||
+ (clockid != CLOCK_MONOTONIC &&
+ clockid != CLOCK_REALTIME &&
+ clockid != CLOCK_REALTIME_ALARM &&
+ clockid != CLOCK_BOOTTIME &&
+ clockid != CLOCK_BOOTTIME_ALARM))
+ return -EINVAL;
+
+ if ((clockid == CLOCK_REALTIME_ALARM ||
+ clockid == CLOCK_BOOTTIME_ALARM) &&
+ !capable(CAP_WAKE_ALARM))
+ return -EPERM;
+
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+
+ init_waitqueue_head(&ctx->wqh);
+ spin_lock_init(&ctx->cancel_lock);
+ ctx->clockid = clockid;
+
+ 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_mono_to_real(0);
+
+ ufd = anon_inode_getfd("[timerfd]", &timerfd_fops, ctx,
+ O_RDWR | (flags & TFD_SHARED_FCNTL_FLAGS));
+ if (ufd < 0)
+ kfree(ctx);
+
+ return ufd;
+}
+
+static int do_timerfd_settime(int ufd, int flags,
+ const struct itimerspec64 *new,
+ struct itimerspec64 *old)
+{
+ struct fd f;
+ struct timerfd_ctx *ctx;
+ int ret;
+
+ if ((flags & ~TFD_SETTIME_FLAGS) ||
+ !itimerspec64_valid(new))
+ return -EINVAL;
+
+ ret = timerfd_fget(ufd, &f);
+ if (ret)
+ return ret;
+ ctx = f.file->private_data;
+
+ if (isalarm(ctx) && !capable(CAP_WAKE_ALARM)) {
+ fdput(f);
+ return -EPERM;
+ }
+
+ timerfd_setup_cancel(ctx, flags);
+
+ /*
+ * We need to stop the existing timer before reprogramming
+ * it to the new values.
+ */
+ for (;;) {
+ spin_lock_irq(&ctx->wqh.lock);
+
+ 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();
+ }
+
+ /*
+ * 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) {
+ 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_timespec64(timerfd_get_remaining(ctx));
+ old->it_interval = ktime_to_timespec64(ctx->tintv);
+
+ /*
+ * Re-program the timer to the new value ...
+ */
+ ret = timerfd_setup(ctx, flags, new);
+
+ spin_unlock_irq(&ctx->wqh.lock);
+ fdput(f);
+ return ret;
+}
+
+static int do_timerfd_gettime(int ufd, struct itimerspec64 *t)
+{
+ struct fd f;
+ struct timerfd_ctx *ctx;
+ int ret = timerfd_fget(ufd, &f);
+ if (ret)
+ return ret;
+ ctx = f.file->private_data;
+
+ spin_lock_irq(&ctx->wqh.lock);
+ if (ctx->expired && ctx->tintv) {
+ ctx->expired = 0;
+
+ 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_timespec64(timerfd_get_remaining(ctx));
+ t->it_interval = ktime_to_timespec64(ctx->tintv);
+ spin_unlock_irq(&ctx->wqh.lock);
+ fdput(f);
+ return 0;
+}
+
+SYSCALL_DEFINE4(timerfd_settime, int, ufd, int, flags,
+ const struct __kernel_itimerspec __user *, utmr,
+ struct __kernel_itimerspec __user *, otmr)
+{
+ struct itimerspec64 new, old;
+ int ret;
+
+ if (get_itimerspec64(&new, utmr))
+ return -EFAULT;
+ ret = do_timerfd_settime(ufd, flags, &new, &old);
+ if (ret)
+ return ret;
+ if (otmr && put_itimerspec64(&old, otmr))
+ return -EFAULT;
+
+ return ret;
+}
+
+SYSCALL_DEFINE2(timerfd_gettime, int, ufd, struct __kernel_itimerspec __user *, otmr)
+{
+ struct itimerspec64 kotmr;
+ int ret = do_timerfd_gettime(ufd, &kotmr);
+ if (ret)
+ return ret;
+ return put_itimerspec64(&kotmr, otmr) ? -EFAULT : 0;
+}
+
+#ifdef CONFIG_COMPAT_32BIT_TIME
+COMPAT_SYSCALL_DEFINE4(timerfd_settime, int, ufd, int, flags,
+ const struct compat_itimerspec __user *, utmr,
+ struct compat_itimerspec __user *, otmr)
+{
+ struct itimerspec64 new, old;
+ int ret;
+
+ if (get_compat_itimerspec64(&new, utmr))
+ return -EFAULT;
+ ret = do_timerfd_settime(ufd, flags, &new, &old);
+ if (ret)
+ return ret;
+ if (otmr && put_compat_itimerspec64(&old, otmr))
+ return -EFAULT;
+ return ret;
+}
+
+COMPAT_SYSCALL_DEFINE2(timerfd_gettime, int, ufd,
+ struct compat_itimerspec __user *, otmr)
+{
+ struct itimerspec64 kotmr;
+ int ret = do_timerfd_gettime(ufd, &kotmr);
+ if (ret)
+ return ret;
+ return put_compat_itimerspec64(&kotmr, otmr) ? -EFAULT : 0;
+}
+#endif