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evdev: Allow open() handler to be interrupted by a signal

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It is possible that the client list lock is taken by other process for too
long due to e.g. IO timeouts. Allow user to terminate open() in this case.

Reviewed by:	markj (as part of D27865)
This commit is contained in:
Vladimir Kondratyev 2020-04-22 01:38:14 +03:00
parent d276eae674
commit 3b8c8b35de
2 changed files with 15 additions and 5 deletions
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11
sys/dev/evdev/cdev.c
View File

@ -126,19 +126,20 @@ evdev_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
mtx_init(&client->ec_buffer_mtx, "evclient", "evdev", MTX_DEF);
knlist_init_mtx(&client->ec_selp.si_note, &client->ec_buffer_mtx);
ret = EVDEV_LIST_LOCK_SIG(evdev);
if (ret != 0)
goto out;
/* Avoid race with evdev_unregister */
EVDEV_LIST_LOCK(evdev);
if (dev->si_drv1 == NULL)
ret = ENODEV;
else
ret = evdev_register_client(evdev, client);
if (ret != 0)
evdev_revoke_client(client);
EVDEV_LIST_UNLOCK(evdev);
out:
if (ret == 0)
ret = devfs_set_cdevpriv(client, evdev_dtor);
else
client->ec_revoked = true;
if (ret != 0) {
debugf(client, "cannot register evdev client");

9
sys/dev/evdev/evdev_private.h
View File

@ -206,6 +206,15 @@ struct evdev_dev
else \
sx_assert(&(evdev)->ev_list_lock, MA_OWNED); \
} while (0)
static inline int
EVDEV_LIST_LOCK_SIG(struct evdev_dev *evdev)
{
if (evdev->ev_lock_type == EV_LOCK_MTX) {
EVDEV_LOCK(evdev);
return (0);
}
return (sx_xlock_sig(&evdev->ev_list_lock));
}
struct evdev_client
{