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
