| Message ID | 20180427133311.5789da57@vento.lan (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
I did test the patch and while it doesn't seem to introduce any negative side effects it does not provide a remedy for the original problem that was seen after introducing 9d659ae14b545c4296e812c70493bfdc999b5c1c (you probably did not expect that either). Cheers, -olli On 27 April 2018 at 18:33, Mauro Carvalho Chehab <mchehab+samsung@kernel.org> wrote: > Em Fri, 27 Apr 2018 16:25:08 +0200 > Olli Salonen <olli.salonen@iki.fi> escreveu: > >> Thanks for the suggestion Antti. >> >> I've tried to add a delay in various places, but haven't seen any >> improvement. However, what I did saw was that if I added an msleep >> after the lock: >> >> static int dvbsky_usb_generic_rw(struct dvb_usb_device *d, >> u8 *wbuf, u16 wlen, u8 *rbuf, u16 rlen) >> { >> int ret; >> struct dvbsky_state *state = d_to_priv(d); >> >> mutex_lock(&d->usb_mutex); >> msleep(20); >> >> The error was seen very within a minute. If I increased the msleep to >> 50, it failed within seconds. This doesn't seem to make sense to me. >> This is the only function where usb_mutex is used. If the mutex is >> held for a longer time, the next attempt to lock the mutex should just >> be delayed a bit, no? > > I don't like the idea of having two mutexes there to protect reading/writing > to data one for "generic" r/w ops, and another one just for streaming > control, with ends by calling the "generic" mutex. > > IMHO, I would get rid of one of the mutexes, e. g. something like the > patch below (untested). > > Regards, > Mauro > > media: dvbsky: use just one mutex for serializing device R/W ops > > Right now, there are two mutexes serializing r/w ops: one "generic" > and another one specifically for stream on/off. > > Clean it a little bit, getting rid of one of the mutexes. > > Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> > > diff --git a/drivers/media/usb/dvb-usb-v2/dvbsky.c b/drivers/media/usb/dvb-usb-v2/dvbsky.c > index 43eb82884555..50553975c39d 100644 > --- a/drivers/media/usb/dvb-usb-v2/dvbsky.c > +++ b/drivers/media/usb/dvb-usb-v2/dvbsky.c > @@ -31,7 +31,6 @@ MODULE_PARM_DESC(disable_rc, "Disable inbuilt IR receiver."); > DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr); > > struct dvbsky_state { > - struct mutex stream_mutex; > u8 ibuf[DVBSKY_BUF_LEN]; > u8 obuf[DVBSKY_BUF_LEN]; > u8 last_lock; > @@ -68,18 +67,17 @@ static int dvbsky_usb_generic_rw(struct dvb_usb_device *d, > > static int dvbsky_stream_ctrl(struct dvb_usb_device *d, u8 onoff) > { > - struct dvbsky_state *state = d_to_priv(d); > int ret; > - u8 obuf_pre[3] = { 0x37, 0, 0 }; > - u8 obuf_post[3] = { 0x36, 3, 0 }; > + static u8 obuf_pre[3] = { 0x37, 0, 0 }; > + static u8 obuf_post[3] = { 0x36, 3, 0 }; > > - mutex_lock(&state->stream_mutex); > - ret = dvbsky_usb_generic_rw(d, obuf_pre, 3, NULL, 0); > + mutex_lock(&d->usb_mutex); > + ret = dvb_usbv2_generic_rw_locked(d, obuf_pre, 3, NULL, 0); > if (!ret && onoff) { > msleep(20); > - ret = dvbsky_usb_generic_rw(d, obuf_post, 3, NULL, 0); > + ret = dvb_usbv2_generic_rw_locked(d, obuf_post, 3, NULL, 0); > } > - mutex_unlock(&state->stream_mutex); > + mutex_unlock(&d->usb_mutex); > return ret; > } > > @@ -744,8 +742,6 @@ static int dvbsky_init(struct dvb_usb_device *d) > if (ret) > return ret; > */ > - mutex_init(&state->stream_mutex); > - > state->last_lock = 0; > > return 0; > > > > Thanks, > Mauro
Em Sat, 28 Apr 2018 08:01:21 +0200 Olli Salonen <olli.salonen@iki.fi> escreveu: > I did test the patch and while it doesn't seem to introduce any > negative side effects it does not provide a remedy for the original > problem that was seen after introducing > 9d659ae14b545c4296e812c70493bfdc999b5c1c (you probably did not expect > that either). Ok, I'll apply it then. Having one less lock makes it cleaner. > > > Cheers, > -olli > > On 27 April 2018 at 18:33, Mauro Carvalho Chehab > <mchehab+samsung@kernel.org> wrote: > > Em Fri, 27 Apr 2018 16:25:08 +0200 > > Olli Salonen <olli.salonen@iki.fi> escreveu: > > > >> Thanks for the suggestion Antti. > >> > >> I've tried to add a delay in various places, but haven't seen any > >> improvement. However, what I did saw was that if I added an msleep > >> after the lock: > >> > >> static int dvbsky_usb_generic_rw(struct dvb_usb_device *d, > >> u8 *wbuf, u16 wlen, u8 *rbuf, u16 rlen) > >> { > >> int ret; > >> struct dvbsky_state *state = d_to_priv(d); > >> > >> mutex_lock(&d->usb_mutex); > >> msleep(20); > >> > >> The error was seen very within a minute. If I increased the msleep to > >> 50, it failed within seconds. This doesn't seem to make sense to me. > >> This is the only function where usb_mutex is used. If the mutex is > >> held for a longer time, the next attempt to lock the mutex should just > >> be delayed a bit, no? > > > > I don't like the idea of having two mutexes there to protect reading/writing > > to data one for "generic" r/w ops, and another one just for streaming > > control, with ends by calling the "generic" mutex. > > > > IMHO, I would get rid of one of the mutexes, e. g. something like the > > patch below (untested). > > > > Regards, > > Mauro > > > > media: dvbsky: use just one mutex for serializing device R/W ops > > > > Right now, there are two mutexes serializing r/w ops: one "generic" > > and another one specifically for stream on/off. > > > > Clean it a little bit, getting rid of one of the mutexes. > > > > Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> > > > > diff --git a/drivers/media/usb/dvb-usb-v2/dvbsky.c b/drivers/media/usb/dvb-usb-v2/dvbsky.c > > index 43eb82884555..50553975c39d 100644 > > --- a/drivers/media/usb/dvb-usb-v2/dvbsky.c > > +++ b/drivers/media/usb/dvb-usb-v2/dvbsky.c > > @@ -31,7 +31,6 @@ MODULE_PARM_DESC(disable_rc, "Disable inbuilt IR receiver."); > > DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr); > > > > struct dvbsky_state { > > - struct mutex stream_mutex; > > u8 ibuf[DVBSKY_BUF_LEN]; > > u8 obuf[DVBSKY_BUF_LEN]; > > u8 last_lock; > > @@ -68,18 +67,17 @@ static int dvbsky_usb_generic_rw(struct dvb_usb_device *d, > > > > static int dvbsky_stream_ctrl(struct dvb_usb_device *d, u8 onoff) > > { > > - struct dvbsky_state *state = d_to_priv(d); > > int ret; > > - u8 obuf_pre[3] = { 0x37, 0, 0 }; > > - u8 obuf_post[3] = { 0x36, 3, 0 }; > > + static u8 obuf_pre[3] = { 0x37, 0, 0 }; > > + static u8 obuf_post[3] = { 0x36, 3, 0 }; > > > > - mutex_lock(&state->stream_mutex); > > - ret = dvbsky_usb_generic_rw(d, obuf_pre, 3, NULL, 0); > > + mutex_lock(&d->usb_mutex); > > + ret = dvb_usbv2_generic_rw_locked(d, obuf_pre, 3, NULL, 0); > > if (!ret && onoff) { > > msleep(20); > > - ret = dvbsky_usb_generic_rw(d, obuf_post, 3, NULL, 0); > > + ret = dvb_usbv2_generic_rw_locked(d, obuf_post, 3, NULL, 0); > > } > > - mutex_unlock(&state->stream_mutex); > > + mutex_unlock(&d->usb_mutex); > > return ret; > > } > > > > @@ -744,8 +742,6 @@ static int dvbsky_init(struct dvb_usb_device *d) > > if (ret) > > return ret; > > */ > > - mutex_init(&state->stream_mutex); > > - > > state->last_lock = 0; > > > > return 0; > > > > > > > > Thanks, > > Mauro Thanks, Mauro
diff --git a/drivers/media/usb/dvb-usb-v2/dvbsky.c b/drivers/media/usb/dvb-usb-v2/dvbsky.c index 43eb82884555..50553975c39d 100644 --- a/drivers/media/usb/dvb-usb-v2/dvbsky.c +++ b/drivers/media/usb/dvb-usb-v2/dvbsky.c @@ -31,7 +31,6 @@ MODULE_PARM_DESC(disable_rc, "Disable inbuilt IR receiver."); DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr); struct dvbsky_state { - struct mutex stream_mutex; u8 ibuf[DVBSKY_BUF_LEN]; u8 obuf[DVBSKY_BUF_LEN]; u8 last_lock; @@ -68,18 +67,17 @@ static int dvbsky_usb_generic_rw(struct dvb_usb_device *d, static int dvbsky_stream_ctrl(struct dvb_usb_device *d, u8 onoff) { - struct dvbsky_state *state = d_to_priv(d); int ret; - u8 obuf_pre[3] = { 0x37, 0, 0 }; - u8 obuf_post[3] = { 0x36, 3, 0 }; + static u8 obuf_pre[3] = { 0x37, 0, 0 }; + static u8 obuf_post[3] = { 0x36, 3, 0 }; - mutex_lock(&state->stream_mutex); - ret = dvbsky_usb_generic_rw(d, obuf_pre, 3, NULL, 0); + mutex_lock(&d->usb_mutex); + ret = dvb_usbv2_generic_rw_locked(d, obuf_pre, 3, NULL, 0); if (!ret && onoff) { msleep(20); - ret = dvbsky_usb_generic_rw(d, obuf_post, 3, NULL, 0); + ret = dvb_usbv2_generic_rw_locked(d, obuf_post, 3, NULL, 0); } - mutex_unlock(&state->stream_mutex); + mutex_unlock(&d->usb_mutex); return ret; } @@ -744,8 +742,6 @@ static int dvbsky_init(struct dvb_usb_device *d) if (ret) return ret; */ - mutex_init(&state->stream_mutex); - state->last_lock = 0; return 0;