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Date: Tue, 08 Jul 2014 20:01:50 +0100 From: Ben Hutchings <ben@...adent.org.uk> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org CC: akpm@...ux-foundation.org, "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>, "Johan Hovold" <jhovold@...il.com> Subject: [PATCH 3.2 034/125] USB: cdc-acm: fix write and suspend race 3.2.61-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Johan Hovold <jhovold@...il.com> 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@...il.com> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> Signed-off-by: Ben Hutchings <ben@...adent.org.uk> --- drivers/usb/class/cdc-acm.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1338,18 +1338,15 @@ static int acm_suspend(struct usb_interf 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); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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