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| author | David Herrmann <dh.herrmann@gmail.com> | 2014-07-29 17:14:15 +0200 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2014-08-25 03:28:05 -0500 |
| commit | 0e0d7520064c9f5668c030afafdbcab242176195 (patch) | |
| tree | 065b9a6d5e0cd495b315040941cc93df32a7617f /drivers/hid | |
| parent | cee5aa1f81b1e88d8de05df226bfd207041954c2 (diff) | |
| download | linux-0e0d7520064c9f5668c030afafdbcab242176195.tar.bz2 | |
HID: uhid: simplify report-cb shutdown
The report-query is blocking, so when user-space destroys a device we have
to wake up any blocking kernel context that is currently in the report-cb.
We used some broken correlation between @report_done and @running so far.
Replace it by a much more obvious use.
We now wake up the report-cb if either @report_done or @running is set.
wake_up() and wait_event() serve as implicit barriers (as they always do)
so no need to use smp_rmb/wmb directly.
Note that @report_done is never reset by anyone but the report-cb, thus
it cannot flip twice while we wait for it. And whenever we set @running,
we afterwards synchronously remove the HID device. Therefore, we wait for
all report-cbs to finish before we return. This way, @running can never
flip to true while we wait for it.
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers/hid')
| -rw-r--r-- | drivers/hid/uhid.c | 11 |
1 files changed, 2 insertions, 9 deletions
diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c index 0cb92e347258..16af4d382391 100644 --- a/drivers/hid/uhid.c +++ b/drivers/hid/uhid.c @@ -172,13 +172,9 @@ static int uhid_hid_get_raw(struct hid_device *hid, unsigned char rnum, spin_unlock_irqrestore(&uhid->qlock, flags); ret = wait_event_interruptible_timeout(uhid->report_wait, - atomic_read(&uhid->report_done), 5 * HZ); + atomic_read(&uhid->report_done) || !uhid->running, + 5 * HZ); - /* - * Make sure "uhid->running" is cleared on shutdown before - * "uhid->report_done" is set. - */ - smp_rmb(); if (!ret || !uhid->running) { ret = -EIO; } else if (ret < 0) { @@ -493,10 +489,7 @@ static int uhid_dev_destroy(struct uhid_device *uhid) if (!uhid->running) return -EINVAL; - /* clear "running" before setting "report_done" */ uhid->running = false; - smp_wmb(); - atomic_set(&uhid->report_done, 1); wake_up_interruptible(&uhid->report_wait); hid_destroy_device(uhid->hid); |