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authorUCHINO Satoshi <satoshi.uchino@toshiba.co.jp>2013-05-23 11:10:11 +0900
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-07-21 18:21:24 -0700
commitf8da12fa870df0d4304a3661352d721d90bd0929 (patch)
tree02aba6ed04f53f1a1e6f47a3fe69ff3c3c22d6f7 /drivers/usb
parent859cfbcdc4374da93fc1258f18f95849c02e52c4 (diff)
usb: gadget: f_mass_storage: add missing memory barrier for thread_wakeup_needed
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@toshiba.co.jp> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/gadget/f_mass_storage.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
index 97666e8b1b9..c35a9ecc576 100644
--- 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 *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;
}