From: UCHINO Satoshi Date: Thu, 23 May 2013 02:10:11 +0000 (+0900) Subject: usb: gadget: f_mass_storage: add missing memory barrier for thread_wakeup_needed X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=f8da12fa870df0d4304a3661352d721d90bd0929;p=karo-tx-linux.git 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 Acked-by: Michal Nazarewicz Signed-off-by: Felipe Balbi Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c index 97666e8b1b95..c35a9ecc576b 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; }