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authorJohan Hovold <jhovold@gmail.com>2014-05-26 19:23:36 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-06-26 15:10:28 -0400
commitbe7978bb5b91ef7168a93cf91acd672dfb65f0d0 (patch)
tree9a79d7836887761448eae32685808906e30de7e1
parent6fa2946224569a4f3f975f86193c02c754acc9d8 (diff)
downloadlinux-linaro-stable-be7978bb5b91ef7168a93cf91acd672dfb65f0d0.tar.gz
USB: cdc-acm: fix write and suspend race
commit 5a345c20c17d87099224a4be12e69e5bd7023dca upstream. 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") 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.c15
1 files changed, 6 insertions, 9 deletions
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index f509888b7ad0..a4573b93c8f2 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1441,18 +1441,15 @@ 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);