svn commit: r264864 - head/sys/dev/usb/wlan

[Rui Paulo]

On Apr 23, 2014, at 20:16, Kevin Lo <kevlo at freebsd.org> wrote:

> Author: kevlo
> Date: Thu Apr 24 03:16:47 2014
> New Revision: 264864
> URL: http://svnweb.freebsd.org/changeset/base/264864
> 
> Log:
>  Fix panic by adding mtx_assert() to urtwn_init_locked() and
>  urtwn_stop_locked().

This was not a panic, but a LOR.

> Modified:
>  head/sys/dev/usb/wlan/if_urtwn.c
> 
> Modified: head/sys/dev/usb/wlan/if_urtwn.c
> ==============================================================================
> --- head/sys/dev/usb/wlan/if_urtwn.c	Thu Apr 24 02:16:23 2014	(r264863)
> +++ head/sys/dev/usb/wlan/if_urtwn.c	Thu Apr 24 03:16:47 2014	(r264864)
> @@ -2054,6 +2054,7 @@ urtwn_load_firmware(struct urtwn_softc *
> 	uint32_t reg;
> 	int mlen, ntries, page, error;
> 
> +	URTWN_UNLOCK(sc);

You didn't need to unlock this early.  The problem was in firmware_get().

> 	/* Read firmware image from the filesystem. */
> 	if ((sc->chip & (URTWN_CHIP_UMC_A_CUT | URTWN_CHIP_92C)) ==
> 	    URTWN_CHIP_UMC_A_CUT)
> @@ -2062,6 +2063,7 @@ urtwn_load_firmware(struct urtwn_softc *
> 		imagename = "urtwn-rtl8192cfwT";
> 
> 	fw = firmware_get(imagename);
> +	URTWN_LOCK(sc);
> 	if (fw == NULL) {
> 		device_printf(sc->sc_dev,
> 		    "failed loadfirmware of file %s\n", imagename);
> @@ -2816,6 +2818,8 @@ urtwn_init_locked(void *arg)
> 	uint32_t reg;
> 	int error;
> 
> +	URTWN_ASSERT_LOCKED(sc);
> +
> 	if (ifp->if_drv_flags & IFF_DRV_RUNNING)
> 		urtwn_stop_locked(ifp);
> 
> @@ -2979,6 +2983,8 @@ urtwn_stop_locked(struct ifnet *ifp)
> {
> 	struct urtwn_softc *sc = ifp->if_softc;
> 
> +	URTWN_ASSERT_LOCKED(sc);
> +
> 	ifp->if_drv_flags &= ~(IFF_DRV_RUNNING | IFF_DRV_OACTIVE);
> 
> 	callout_stop(&sc->sc_watchdog_ch);

This is fine, but I wonder if the firmware API should be changed.  The problem with this approach, and all USB WiFi drivers, is that by unlocking the mutex, the mutual exclusion protection is lost... 

--
Rui Paulo