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 3.4-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-3.4 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
@@ -511,6 +511,7 @@ 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)
@@ -730,6 +731,7 @@ 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-3.4/usb-gadget-f_mass_storage-add-missing-memory-barrier-for-thread_wakeup_needed.patch
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