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| author | Johan Hovold <jhovold@gmail.com> | 2014-05-26 19:23:36 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-05-27 15:04:08 -0700 |
| commit | 5a345c20c17d87099224a4be12e69e5bd7023dca (patch) | |
| tree | 8a5c3fd60129a12f9bd33e7f98dd4135e5bbf2c8 | |
| parent | 90419cfcb5d9c889b10dc51363c56a4d394d670e (diff) | |
| download | linux-5a345c20c17d87099224a4be12e69e5bd7023dca.tar.gz linux-5a345c20c17d87099224a4be12e69e5bd7023dca.tar.bz2 linux-5a345c20c17d87099224a4be12e69e5bd7023dca.zip | |
USB: cdc-acm: fix write and suspend race
Fix race between write() and suspend() which could lead to writes being
dropped (or I/O while suspended) if the device is runtime suspended
while a write request is being processed.
Specifically, suspend() releases the write_lock after determining the
device is idle but before incrementing the susp_count, thus leaving a
window where a concurrent write() can submit an urb.
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>
| -rw-r--r-- | drivers/usb/class/cdc-acm.c | 15 |
1 files changed, 6 insertions, 9 deletions
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 904efb6035b0..3bd4226c13dc 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1514,18 +1514,15 @@ static int acm_suspend(struct usb_interface *intf, pm_message_t message) struct acm *acm = usb_get_intfdata(intf); int cnt; + spin_lock_irq(&acm->read_lock); + spin_lock(&acm->write_lock); if (PMSG_IS_AUTO(message)) { - int b; - - spin_lock_irq(&acm->write_lock); - b = acm->transmitting; - spin_unlock_irq(&acm->write_lock); - if (b) + if (acm->transmitting) { + spin_unlock(&acm->write_lock); + spin_unlock_irq(&acm->read_lock); return -EBUSY; + } } - - spin_lock_irq(&acm->read_lock); - spin_lock(&acm->write_lock); cnt = acm->susp_count++; spin_unlock(&acm->write_lock); spin_unlock_irq(&acm->read_lock); |