Patch "usb: gadget: f_mass_storage: add missing memory barrier for thread_wakeup_needed" has been added to the 3.10-stable tree

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This is a note to let you know that I've just added the patch titled

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

to the 3.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-gadget-f_mass_storage-add-missing-memory-barrier-for-thread_wakeup_needed.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From d68c277b501889b3a50c179d1c3d704db7947b83 Mon Sep 17 00:00:00 2001
From: UCHINO Satoshi <satoshi.uchino@xxxxxxxxxxxxx>
Date: Thu, 23 May 2013 11:10:11 +0900
Subject: usb: gadget: f_mass_storage: add missing memory barrier for thread_wakeup_needed

From: UCHINO Satoshi <satoshi.uchino@xxxxxxxxxxxxx>

commit d68c277b501889b3a50c179d1c3d704db7947b83 upstream.

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;
	}

Signed-off-by: UCHINO Satoshi <satoshi.uchino@xxxxxxxxxxxxx>
Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
Signed-off-by: Felipe Balbi <balbi@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/gadget/f_mass_storage.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/usb/gadget/f_mass_storage.c
+++ b/drivers/usb/gadget/f_mass_storage.c
@@ -413,6 +413,7 @@ static int fsg_set_halt(struct fsg_dev *
 /* 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_commo
 	}
 	__set_current_state(TASK_RUNNING);
 	common->thread_wakeup_needed = 0;
+	smp_rmb();	/* ensure the latest bh->state is visible */
 	return rc;
 }
 


Patches currently in stable-queue which might be from satoshi.uchino@xxxxxxxxxxxxx are

queue-3.10/usb-gadget-f_mass_storage-add-missing-memory-barrier-for-thread_wakeup_needed.patch
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