This is a note to let you know that I've just added the patch titled
USB: usb_wwan: fix race between write and resume
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>From d9e93c08d8d985e5ef89436ebc9f4aad7e31559f Mon Sep 17 00:00:00 2001
From: xiao jin <[email protected]>
Date: Mon, 26 May 2014 19:23:14 +0200
Subject: USB: usb_wwan: fix race between write and resume
We find a race between write and resume. usb_wwan_resume run play_delayed()
and spin_unlock, but intfdata->suspended still is not set to zero.
At this time usb_wwan_write is called and anchor the urb to delay
list. Then resume keep running but the delayed urb have no chance
to be commit until next resume. If the time of next resume is far
away, tty will be blocked in tty_wait_until_sent during time. The
race also can lead to writes being reordered.
This patch put play_Delayed and intfdata->suspended together in the
spinlock, it's to avoid the write race during resume.
Fixes: 383cedc3bb43 ("USB: serial: full autosuspend support for the
option driver")
Signed-off-by: xiao jin <[email protected]>
Signed-off-by: Zhang, Qi1 <[email protected]>
Reviewed-by: David Cohen <[email protected]>
Cc: <[email protected]> # v2.6.32
Signed-off-by: Johan Hovold <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/usb/serial/usb_wwan.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/drivers/usb/serial/usb_wwan.c b/drivers/usb/serial/usb_wwan.c
index 47ad7550c5a6..112693a4100b 100644
--- a/drivers/usb/serial/usb_wwan.c
+++ b/drivers/usb/serial/usb_wwan.c
@@ -660,17 +660,15 @@ int usb_wwan_resume(struct usb_serial *serial)
}
}
+ spin_lock_irq(&intfdata->susp_lock);
for (i = 0; i < serial->num_ports; i++) {
/* walk all ports */
port = serial->port[i];
portdata = usb_get_serial_port_data(port);
/* skip closed ports */
- spin_lock_irq(&intfdata->susp_lock);
- if (!portdata || !portdata->opened) {
- spin_unlock_irq(&intfdata->susp_lock);
+ if (!portdata || !portdata->opened)
continue;
- }
for (j = 0; j < N_IN_URB; j++) {
urb = portdata->in_urbs[j];
@@ -683,9 +681,7 @@ int usb_wwan_resume(struct usb_serial *serial)
}
}
play_delayed(port);
- spin_unlock_irq(&intfdata->susp_lock);
}
- spin_lock_irq(&intfdata->susp_lock);
intfdata->suspended = 0;
spin_unlock_irq(&intfdata->susp_lock);
err_out:
--
1.9.0
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