| From d68c277b501889b3a50c179d1c3d704db7947b83 Mon Sep 17 00:00:00 2001 |
| From: UCHINO Satoshi <satoshi.uchino@toshiba.co.jp> |
| 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@toshiba.co.jp> |
| |
| 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> |
| |
| --- |
| 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; |
| } |
| |
