Re: [PATCH] ALSA: sb: Convert timers to use timer_setup()

[Takashi Iwai]

On Tue, 24 Oct 2017 21:24:58 +0200,
Takashi Iwai wrote:
> 
> On Tue, 24 Oct 2017 17:34:58 +0200,
> Kees Cook wrote:
> > 
> > In preparation for unconditionally passing the struct timer_list pointer to
> > all timer callbacks, switch to using the new timer_setup() and from_timer()
> > to pass the timer pointer explicitly.
> > 
> > Cc: Jaroslav Kysela <perex@xxxxxxxx>
> > Cc: Takashi Iwai <tiwai@xxxxxxxx>
> > Cc: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
> > Cc: alsa-devel@xxxxxxxxxxxxxxxx
> > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> > ---
> >  include/sound/sb.h         |  1 +
> >  sound/isa/sb/emu8000_pcm.c |  6 +++---
> >  sound/isa/sb/sb8_midi.c    | 12 ++++++------
> >  3 files changed, 10 insertions(+), 9 deletions(-)
> > 
> > diff --git a/include/sound/sb.h b/include/sound/sb.h
> > index bacefaee411a..4aef395189ec 100644
> > --- a/include/sound/sb.h
> > +++ b/include/sound/sb.h
> > @@ -83,6 +83,7 @@ struct snd_sb {
> >  	unsigned int playback_format;
> >  	unsigned int capture_format;
> >  	struct timer_list midi_timer;
> > +	struct snd_rawmidi_substream *timer_substream;
> 
> This is superfluous.  It's identical with chip->midi_substream_output,
> as this timer is used only for the output stream.
 
... and the revised patch is below.


> > @@ -230,9 +230,9 @@ static void snd_sb8dsp_midi_output_trigger(struct snd_rawmidi_substream *substre
> >  	spin_lock_irqsave(&chip->open_lock, flags);
> >  	if (up) {
> >  		if (!(chip->open & SB_OPEN_MIDI_OUTPUT_TRIGGER)) {
> > -			setup_timer(&chip->midi_timer,
> > -				    snd_sb8dsp_midi_output_timer,
> > -				    (unsigned long) substream);
> > +			chip->timer_substream = substream;
> > +			timer_setup(&chip->midi_timer,
> > +				    snd_sb8dsp_midi_output_timer, 0);
> 
> I think it's OK to replace straightforwardly like this for this
> particular patch (so that the conversion becomes clearer), but ideally
> speaking, timer_setup() should go into either *_output_open() or
> snd_sb8dsp_midi() so that it's called only once per stream open or
> once at creation.
> 
> And, looking at the code closely now, it seems that del_timer_sync()
> is missing at the close side, too, but maybe it didn't matter much for
> such an old hardware :)

In the end, I kept timer_setup() call placed as is in v1 patch.

This call will be moved to the more appropriate place in another
patch, as well as the additional call of missing del_timer_sync() at
*_close().


thanks,

Takashi

-- 8< --
From: Kees Cook <keescook@xxxxxxxxxxxx>
Subject: [PATCH v2] ALSA: sb: Convert timers to use timer_setup()

In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly.

Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---

v1->v2: Re-use the existing chip->midi_substream_output instead of assigning
  a new field to struct snd_sb

 sound/isa/sb/emu8000_pcm.c |  6 +++---
 sound/isa/sb/sb8_midi.c    | 11 +++++------
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/sound/isa/sb/emu8000_pcm.c b/sound/isa/sb/emu8000_pcm.c
index 8f34551abd8d..bc5af71d3bdb 100644
--- a/sound/isa/sb/emu8000_pcm.c
+++ b/sound/isa/sb/emu8000_pcm.c
@@ -193,9 +193,9 @@ static inline int emu8k_get_curpos(struct snd_emu8k_pcm *rec, int ch)
  * timer interrupt handler
  * check the current position and update the period if necessary.
  */
-static void emu8k_pcm_timer_func(unsigned long data)
+static void emu8k_pcm_timer_func(struct timer_list *t)
 {
-	struct snd_emu8k_pcm *rec = (struct snd_emu8k_pcm *)data;
+	struct snd_emu8k_pcm *rec = from_timer(rec, t, timer);
 	int ptr, delta;
 
 	spin_lock(&rec->timer_lock);
@@ -241,7 +241,7 @@ static int emu8k_pcm_open(struct snd_pcm_substream *subs)
 	runtime->private_data = rec;
 
 	spin_lock_init(&rec->timer_lock);
-	setup_timer(&rec->timer, emu8k_pcm_timer_func, (unsigned long)rec);
+	timer_setup(&rec->timer, emu8k_pcm_timer_func, 0);
 
 	runtime->hw = emu8k_pcm_hw;
 	runtime->hw.buffer_bytes_max = emu->mem_size - LOOP_BLANK_SIZE * 3;
diff --git a/sound/isa/sb/sb8_midi.c b/sound/isa/sb/sb8_midi.c
index bd672abb4854..05ba2c6b1a8c 100644
--- a/sound/isa/sb/sb8_midi.c
+++ b/sound/isa/sb/sb8_midi.c
@@ -209,10 +209,10 @@ static void snd_sb8dsp_midi_output_write(struct snd_rawmidi_substream *substream
 	}
 }
 
-static void snd_sb8dsp_midi_output_timer(unsigned long data)
+static void snd_sb8dsp_midi_output_timer(struct timer_list *t)
 {
-	struct snd_rawmidi_substream *substream = (struct snd_rawmidi_substream *) data;
-	struct snd_sb * chip = substream->rmidi->private_data;
+	struct snd_sb *chip = from_timer(chip, t, midi_timer);
+	struct snd_rawmidi_substream *substream = chip->midi_substream_output;
 	unsigned long flags;
 
 	spin_lock_irqsave(&chip->open_lock, flags);
@@ -230,9 +230,8 @@ static void snd_sb8dsp_midi_output_trigger(struct snd_rawmidi_substream *substre
 	spin_lock_irqsave(&chip->open_lock, flags);
 	if (up) {
 		if (!(chip->open & SB_OPEN_MIDI_OUTPUT_TRIGGER)) {
-			setup_timer(&chip->midi_timer,
-				    snd_sb8dsp_midi_output_timer,
-				    (unsigned long) substream);
+			timer_setup(&chip->midi_timer,
+				    snd_sb8dsp_midi_output_timer, 0);
 			mod_timer(&chip->midi_timer, 1 + jiffies);
 			chip->open |= SB_OPEN_MIDI_OUTPUT_TRIGGER;
 		}
-- 
2.14.2