Commit d68c277b authored May 23, 2013 by UCHINO Satoshi Committed by Felipe Balbi Jun 10, 2013

usb: gadget: f_mass_storage: add missing memory barrier for thread_wakeup_needed



Without this memory barrier, the file-storage thread may fail to
escape from the following while loop, because it may observe new
common->thread_wakeup_needed and old bh->state which are updated by
the callback functions.

	/* Wait for the CBW to arrive */
	while (bh->state != BUF_STATE_FULL) {
		rc = sleep_thread(common);
		if (rc)
			return rc;
	}

Cc: stable@vger.kernel.org
Signed-off-by: UCHINO Satoshi <satoshi.uchino@toshiba.co.jp>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

parent eb127cb5

drivers/usb/gadget/f_mass_storage.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -413,6 +413,7 @@ static int fsg_set_halt(struct fsg_dev fsg, struct usb_ep ep)
		/* Caller must hold fsg->lock */
		static void wakeup_thread(struct fsg_common *common)
		{
		smp_wmb(); /* ensure the write of bh->state is complete */
		/* Tell the main thread that something has happened */
		common->thread_wakeup_needed = 1;
		if (common->thread_task)
		@@ -632,6 +633,7 @@ static int sleep_thread(struct fsg_common *common)
		}
		__set_current_state(TASK_RUNNING);
		common->thread_wakeup_needed = 0;
		smp_rmb(); /* ensure the latest bh->state is visible */
		return rc;
		}