Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 07/24] usb: gadget: f_mass_storage: add missing memory barrier for thread_wakeup_needed | Date | Thu, 18 Jul 2013 19:24:39 -0700 |
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3.4-stable review patch. If anyone has any objections, please let me know.
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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 @@ -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; }
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