@@ -1447,27 +1447,20 @@ 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);
}
/*
@@ -1475,12 +1468,14 @@ 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;
}
This is a note to let you know that I have just added a patch titled USB: cdc-acm: fix write and resume race to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.11.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From e1f91ef102f28fa47cce38249a0497914b6908a0 Mon Sep 17 00:00:00 2001 From: Johan Hovold <jhovold@gmail.com> Date: Mon, 26 May 2014 19:23:37 +0200 Subject: USB: cdc-acm: fix write and resume race commit e144ed28bed10684f9aaec6325ed974d53f76110 upstream. 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") Signed-off-by: Johan Hovold <jhovold@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/usb/class/cdc-acm.c | 23 +++++++++-------------- 1 file changed, 9 insertions(+), 14 deletions(-) -- 1.9.1