diff options
| author | Johan Hovold <jhovold@gmail.com> | 2014-05-26 19:23:37 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-05-27 15:04:09 -0700 |
| commit | e144ed28bed10684f9aaec6325ed974d53f76110 (patch) | |
| tree | bac73dbef9647f9c5af0f1d852e1c89fe838c982 /drivers/usb/class/cdc-acm.c | |
| parent | 5a345c20c17d87099224a4be12e69e5bd7023dca (diff) | |
USB: cdc-acm: fix write and resume race
Fix race between write() and resume() due to improper locking that could
lead to writes being reordered.
Resume must be done atomically and susp_count be protected by the
write_lock in order to prevent racing with write(). This could otherwise
lead to writes being reordered if write() grabs the write_lock after
susp_count is decremented, but before the delayed urb is submitted.
Fixes: 11ea859d64b6 ("USB: additional power savings for cdc-acm devices
that support remote wakeup")
Cc: <stable@vger.kernel.org> # v2.6.27
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/class/cdc-acm.c')
| -rw-r--r-- | drivers/usb/class/cdc-acm.c | 23 |
1 files changed, 9 insertions, 14 deletions
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 3bd4226c13dc..e72a657a6177 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1541,27 +1541,20 @@ static int acm_resume(struct usb_interface *intf) struct acm *acm = usb_get_intfdata(intf); struct acm_wb *wb; int rv = 0; - int cnt; spin_lock_irq(&acm->read_lock); - acm->susp_count -= 1; - cnt = acm->susp_count; - spin_unlock_irq(&acm->read_lock); + spin_lock(&acm->write_lock); - if (cnt) - return 0; + if (--acm->susp_count) + goto out; if (test_bit(ASYNCB_INITIALIZED, &acm->port.flags)) { - rv = usb_submit_urb(acm->ctrlurb, GFP_NOIO); + rv = usb_submit_urb(acm->ctrlurb, GFP_ATOMIC); - spin_lock_irq(&acm->write_lock); if (acm->delayed_wb) { wb = acm->delayed_wb; acm->delayed_wb = NULL; - spin_unlock_irq(&acm->write_lock); acm_start_wb(acm, wb); - } else { - spin_unlock_irq(&acm->write_lock); } /* @@ -1569,12 +1562,14 @@ static int acm_resume(struct usb_interface *intf) * do the write path at all cost */ if (rv < 0) - goto err_out; + goto out; - rv = acm_submit_read_urbs(acm, GFP_NOIO); + rv = acm_submit_read_urbs(acm, GFP_ATOMIC); } +out: + spin_unlock(&acm->write_lock); + spin_unlock_irq(&acm->read_lock); -err_out: return rv; } |