Date: Tue, 29 Apr 2014 14:07:21 -0700 From: Rui Paulo <rpaulo@felyko.com> To: Kevin Lo <kevlo@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r264864 - head/sys/dev/usb/wlan Message-ID: <1D92F901-019B-436A-9926-7D7AB4F4C858@felyko.com> In-Reply-To: <201404240316.s3O3GlUl093950@svn.freebsd.org> References: <201404240316.s3O3GlUl093950@svn.freebsd.org>
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On Apr 23, 2014, at 20:16, Kevin Lo <kevlo@freebsd.org> wrote: > Author: kevlo > Date: Thu Apr 24 03:16:47 2014 > New Revision: 264864 > URL: http://svnweb.freebsd.org/changeset/base/264864 >=20 > 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 >=20 > Modified: head/sys/dev/usb/wlan/if_urtwn.c > = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D > --- 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; >=20 > + 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)) =3D=3D > URTWN_CHIP_UMC_A_CUT) > @@ -2062,6 +2063,7 @@ urtwn_load_firmware(struct urtwn_softc * > imagename =3D "urtwn-rtl8192cfwT"; >=20 > fw =3D firmware_get(imagename); > + URTWN_LOCK(sc); > if (fw =3D=3D 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; >=20 > + URTWN_ASSERT_LOCKED(sc); > + > if (ifp->if_drv_flags & IFF_DRV_RUNNING) > urtwn_stop_locked(ifp); >=20 > @@ -2979,6 +2983,8 @@ urtwn_stop_locked(struct ifnet *ifp) > { > struct urtwn_softc *sc =3D ifp->if_softc; >=20 > + URTWN_ASSERT_LOCKED(sc); > + > ifp->if_drv_flags &=3D ~(IFF_DRV_RUNNING | IFF_DRV_OACTIVE); >=20 > 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...=20 -- Rui Paulo
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