Messages in this thread | | | Date | Wed, 7 Nov 2012 18:39:45 +0800 | Subject | Re: [PATCH] firmware loader: Fix the race FW_STATUS_DONE is followed by class_timeout | From | Ming Lei <> |
| |
On Thu, Nov 8, 2012 at 12:45 AM, Chuansheng Liu <chuansheng.liu@intel.com> wrote: > > There is a race condition as below when calling request_firmware(): > > CPU1 CPU2 > write 0 > loading > mutex_lock(&fw_lock); > ... > set_bit FW_STATUS_DONE class_timeout is coming > set_bit FW_STATUS_ABORT > complete_all &completion > ... > mutex_unlock(&fw_lock)
Good catch, but your fix isn't correct.
> > In this time, the bit FW_STATUS_DONE and FW_STATUS_ABORT are set, > and request_firmware() will return failure due to condition in > _request_firmware_load(): > > if (!buf->size || test_bit(FW_STATUS_ABORT, &buf->status)) > retval = -ENOENT; > > But from the above scenerio, it should be a succcessful requesting. > So we need judge if the FW_STATUS_DONE is set before calling abort > in timeout function firmware_class_timeout(). > > Signed-off-by: liu chuansheng <chuansheng.liu@intel.com> > --- > drivers/base/firmware_class.c | 7 +++++++ > 1 files changed, 7 insertions(+), 0 deletions(-) > > diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c > index 8945f4e..35fffd8 100644 > --- a/drivers/base/firmware_class.c > +++ b/drivers/base/firmware_class.c > @@ -671,6 +671,13 @@ static void firmware_class_timeout(u_long data) > { > struct firmware_priv *fw_priv = (struct firmware_priv *) data; > > + mutex_lock(&fw_lock);
mutex can't be used in interrupt context, so one candidate fix is to convert the timeout timer into delayed work, and hold the 'fw_lock' during the work function.
> + if (test_bit(FW_STATUS_DONE, &(fw_priv->buf->status))) { > + mutex_unlock(&fw_lock); > + return; > + } > + mutex_unlock(&fw_lock); > + > fw_load_abort(fw_priv); > }
Also the lock of 'fw_lock' should be held when setting 'FW_STATUS_DONE' in _request_firmware_load().
Could you send out a new patch to fix the race?
Thanks, -- Ming Lei
| |