From: Corey Minyard <cminyard@xxxxxxxxxx>
This is for the read data pretimeout governor.
Signed-off-by: Corey Minyard <cminyard@xxxxxxxxxx>
---
drivers/watchdog/watchdog_core.c | 3 +
drivers/watchdog/watchdog_dev.c | 113 +++++++++++++++++++++++++++++++
include/linux/watchdog.h | 5 ++
3 files changed, 121 insertions(+)
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index 21e8085b848b..80149ac229fc 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -216,6 +216,9 @@ static int __watchdog_register_device(struct watchdog_device *wdd)
return id;
wdd->id = id;
+ spin_lock_init(&wdd->readlock);
+ init_waitqueue_head(&wdd->read_q);
+
ret = watchdog_dev_register(wdd);
if (ret) {
ida_simple_remove(&watchdog_ida, id);
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index dbd2ad4c9294..8e8304607a8c 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -44,6 +44,8 @@
#include <linux/types.h> /* For standard types (like size_t) */
#include <linux/watchdog.h> /* For watchdog specific items */
#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
+#include <linux/poll.h> /* For poll_table/... */
+#include <linux/sched/signal.h> /* For signal_pending */
#include <uapi/linux/sched/types.h> /* For struct sched_param */
@@ -929,12 +931,120 @@ static int watchdog_release(struct inode *inode, struct file *file)
return 0;
}
+static ssize_t watchdog_read(struct file *file,
+ char __user *buf,
+ size_t count,
+ loff_t *ppos)
+{
+ struct watchdog_core_data *wd_data = file->private_data;
+ struct watchdog_device *wdd;
+ int err = 0;
+ wait_queue_entry_t wait;
+ char dummy = 1;
+
+ if (count <= 0)
+ return 0;
+
+ mutex_lock(&wd_data->lock);
+
+ wdd = wd_data->wdd;
+ if (!wdd)
+ goto done;
+
+ /*
+ * Reading returns if the pretimeout has gone off, and it only does
+ * it once per pretimeout.
+ */
+ spin_lock_irq(&wdd->readlock);
+ while (!wdd->data_to_read) {
+ if (file->f_flags & O_NONBLOCK) {
+ err = -EAGAIN;
+ goto out;
+ }
+
+ init_waitqueue_entry(&wait, current);
+ add_wait_queue(&wdd->read_q, &wait);
+ set_current_state(TASK_INTERRUPTIBLE);
+ spin_unlock_irq(&wdd->readlock);
+ schedule();
+ spin_lock_irq(&wdd->readlock);
+ remove_wait_queue(&wdd->read_q, &wait);
+
+ if (signal_pending(current)) {
+ err = -ERESTARTSYS;
+ goto out;
+ }
+ }
+ dummy = wdd->data_to_read;
+ wdd->data_to_read = 0;
+
+ out:
+ spin_unlock_irq(&wdd->readlock);
+
+ if (err == 0) {
+ if (copy_to_user(buf, &dummy, 1))
+ err = -EFAULT;
+ else
+ err = 1;
+ }
+
+ done:
+ mutex_unlock(&wd_data->lock);
+
+ return err;
+}
+
+static __poll_t watchdog_poll(struct file *file, poll_table *wait)
+{
+ struct watchdog_core_data *wd_data = file->private_data;
+ struct watchdog_device *wdd;
+ __poll_t mask = 0;
+
+ mutex_lock(&wd_data->lock);
+
+ wdd = wd_data->wdd;
+ if (!wdd)
+ goto done;
+
+ poll_wait(file, &wdd->read_q, wait);
+
+ spin_lock_irq(&wdd->readlock);
+ if (wdd->data_to_read)
+ mask |= (EPOLLIN | EPOLLRDNORM);
+ spin_unlock_irq(&wdd->readlock);
+
+done:
+ mutex_unlock(&wd_data->lock);
+ return mask;
+}
+
+static int watchdog_fasync(int fd, struct file *file, int on)
+{
+ struct watchdog_core_data *wd_data = file->private_data;
+ struct watchdog_device *wdd;
+ int err = -ENODEV;
+
+ mutex_lock(&wd_data->lock);
+
+ wdd = wd_data->wdd;
+ if (!wdd)
+ goto done;
+
+ err = fasync_helper(fd, file, on, &wdd->fasync_q);
+done:
+ mutex_unlock(&wd_data->lock);
+ return err;
+}
+
static const struct file_operations watchdog_fops = {
.owner = THIS_MODULE,
.write = watchdog_write,
.unlocked_ioctl = watchdog_ioctl,
.open = watchdog_open,
.release = watchdog_release,
+ .read = watchdog_read,
+ .poll = watchdog_poll,
+ .fasync = watchdog_fasync,
};
static struct miscdevice watchdog_miscdev = {
@@ -970,6 +1080,9 @@ static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
if (IS_ERR_OR_NULL(watchdog_kworker))
return -ENODEV;
+ spin_lock_init(&wdd->readlock);
+ init_waitqueue_head(&wdd->read_q);
+
kthread_init_work(&wd_data->work, watchdog_ping_work);
hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
wd_data->timer.function = watchdog_timer_expired;
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index 417d9f37077a..e34501a822f0 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -117,6 +117,11 @@ struct watchdog_device {
#define WDOG_HW_RUNNING 3 /* True if HW watchdog running */
#define WDOG_STOP_ON_UNREGISTER 4 /* Should be stopped on unregister */
struct list_head deferred;
+
+ spinlock_t readlock;
+ bool data_to_read;
+ struct wait_queue_head read_q;
+ struct fasync_struct *fasync_q;
};
#define WATCHDOG_NOWAYOUT IS_BUILTIN(CONFIG_WATCHDOG_NOWAYOUT)
--
2.17.1
