On 08/12/2012 04:15 AM, Mauro Carvalho Chehab wrote: > Devin/Antti, > > As Juergen mentioned your help on this patch, do you mind helping reviewing > and testing it? > > Touching on those semaphores can be very tricky, as anything wrong may cause > a driver hangup. So, it is great to have more pair of eyes looking on it. > > While I didn't test the code (too busy trying to clean up my long queue - > currently with still 200+ patches left), I did a careful review at the > semaphore code there, and it seems this approach will work. > > At least, the first hunk looks perfect for me. The second hunk seems > a little more worrying, as the dvb core might be waiting forever for > a lock on a device that was already removed. > > In order to test it in practice, I think we need to remove an USB device > by hand while tuning it, and see if the core will not lock the device > forever. > > What do you think? > Mauro > > -------- Mensagem original -------- > Assunto: [PATCH, RFC] Fix DVB ioctls failing if frontend open/closed too fast > Data: Wed, 1 Aug 2012 00:22:16 +0200 > De: Juergen Lock <nox@xxxxxxxxxxxxxxxxxx> > Para: linux-media@xxxxxxxxxxxxxxx > CC: hselasky@xxxxxxx > > That likely fxes this MythTV ticket: > > http://code.mythtv.org/trac/ticket/10830 > > (which btw affects all usb tuners I tested as well, pctv452e, > dib0700, af9015) pctv452e is still possibly broken with MythTV > even after this fix; it does work with VDR here tho despite I2C > errors. > > Reduced testcase: > > http://people.freebsd.org/~nox/tmp/ioctltst.c > > Thanx to devinheitmueller and crope from #linuxtv for helping with > this fix! :) > > Signed-off-by: Juergen Lock <nox@xxxxxxxxxxxxxxxxxx> > > --- a/drivers/media/dvb/dvb-core/dvb_frontend.c > +++ b/drivers/media/dvb/dvb-core/dvb_frontend.c > @@ -604,6 +604,7 @@ static int dvb_frontend_thread(void *dat > enum dvbfe_algo algo; > > bool re_tune = false; > + bool semheld = false; > > dprintk("%s\n", __func__); > > @@ -627,6 +628,8 @@ restart: > > if (kthread_should_stop() || dvb_frontend_is_exiting(fe)) { > /* got signal or quitting */ > + if (!down_interruptible (&fepriv->sem)) > + semheld = true; > fepriv->exit = DVB_FE_NORMAL_EXIT; > break; > } > @@ -742,6 +745,8 @@ restart: > fepriv->exit = DVB_FE_NO_EXIT; > mb(); > > + if (semheld) > + up(&fepriv->sem); > dvb_frontend_wakeup(fe); > return 0; > } > @@ -1804,16 +1809,20 @@ static int dvb_frontend_ioctl(struct fil > > dprintk("%s (%d)\n", __func__, _IOC_NR(cmd)); > > - if (fepriv->exit != DVB_FE_NO_EXIT) > + if (down_interruptible (&fepriv->sem)) > + return -ERESTARTSYS; > + > + if (fepriv->exit != DVB_FE_NO_EXIT) { > + up(&fepriv->sem); > return -ENODEV; > + } > > if ((file->f_flags & O_ACCMODE) == O_RDONLY && > (_IOC_DIR(cmd) != _IOC_READ || cmd == FE_GET_EVENT || > - cmd == FE_DISEQC_RECV_SLAVE_REPLY)) > + cmd == FE_DISEQC_RECV_SLAVE_REPLY)) { > + up(&fepriv->sem); > return -EPERM; > - > - if (down_interruptible (&fepriv->sem)) > - return -ERESTARTSYS; > + } > > if ((cmd == FE_SET_PROPERTY) || (cmd == FE_GET_PROPERTY)) > err = dvb_frontend_ioctl_properties(file, cmd, parg); > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > +1 This one resolve annoying mythtv-setup output: "E FE_GET_INFO ioctl failed (/dev/dvb/adapter0/frontend0) eno: No such device (19)" http://www.gossamer-threads.com/lists/mythtv/dev/513410 But, there is a new one! Just had a little déjà vu :) Cheers, poma -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
