From: Takashi Iwai <tiwai@suse.de>
Date: Wed, 9 Jan 2019 11:02:56 +0000 (+0100)
Subject: pcm: Preserve period_event in snd_pcm_hw_sw_params() call
X-Git-Tag: v1.1.9~27
X-Git-Url: https://git.alsa-project.org/?a=commitdiff_plain;h=9c1439a76cea33d2cec65a42d499230d2f9a5205;p=alsa-lib.git

pcm: Preserve period_event in snd_pcm_hw_sw_params() call

snd_pcm_hw_sw_params() in pcm_hw.c tries to abuse the reserved bits
for passing period_Event flag.  In this hackish way, we clear the
reserved bits at beginning, and restore before returning.  However,
the code paths that return earlier don't restore the value, hence when
user calls this function twice, it may pass an unexpected value.

This patch fixes the failure, restoring the value always before
returning from the function.

Reported-by: Jamey Sharp <jamey@minilop.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---

diff --git a/src/pcm/pcm_hw.c b/src/pcm/pcm_hw.c
index 59a24200..91370a88 100644
--- a/src/pcm/pcm_hw.c
+++ b/src/pcm/pcm_hw.c
@@ -496,7 +496,7 @@ static int snd_pcm_hw_hw_free(snd_pcm_t *pcm)
 static int snd_pcm_hw_sw_params(snd_pcm_t *pcm, snd_pcm_sw_params_t * params)
 {
 	snd_pcm_hw_t *hw = pcm->private_data;
-	int fd = hw->fd, err;
+	int fd = hw->fd, err = 0;
 	int old_period_event = sw_get_period_event(params);
 	sw_set_period_event(params, 0);
 	if ((snd_pcm_tstamp_t) params->tstamp_mode == pcm->tstamp_mode &&
@@ -508,22 +508,25 @@ static int snd_pcm_hw_sw_params(snd_pcm_t *pcm, snd_pcm_sw_params_t * params)
 	    params->silence_size == pcm->silence_size &&
 	    old_period_event == hw->period_event) {
 		hw->mmap_control->avail_min = params->avail_min;
-		return issue_avail_min(hw);
+		err = issue_avail_min(hw);
+		goto out;
 	}
 	if (params->tstamp_type == SND_PCM_TSTAMP_TYPE_MONOTONIC_RAW &&
 	    hw->version < SNDRV_PROTOCOL_VERSION(2, 0, 12)) {
 		SYSMSG("Kernel doesn't support SND_PCM_TSTAMP_TYPE_MONOTONIC_RAW");
-		return -EINVAL;
+		err = -EINVAL;
+		goto out;
 	}
 	if (params->tstamp_type == SND_PCM_TSTAMP_TYPE_MONOTONIC &&
 	    hw->version < SNDRV_PROTOCOL_VERSION(2, 0, 5)) {
 		SYSMSG("Kernel doesn't support SND_PCM_TSTAMP_TYPE_MONOTONIC");
-		return -EINVAL;
+		err = -EINVAL;
+		goto out;
 	}
 	if (ioctl(fd, SNDRV_PCM_IOCTL_SW_PARAMS, params) < 0) {
 		err = -errno;
 		SYSMSG("SNDRV_PCM_IOCTL_SW_PARAMS failed (%i)", err);
-		return err;
+		goto out;
 	}
 	if ((snd_pcm_tstamp_type_t) params->tstamp_type != pcm->tstamp_type) {
 		if (hw->version < SNDRV_PROTOCOL_VERSION(2, 0, 12)) {
@@ -532,20 +535,21 @@ static int snd_pcm_hw_sw_params(snd_pcm_t *pcm, snd_pcm_sw_params_t * params)
 			if (ioctl(fd, SNDRV_PCM_IOCTL_TSTAMP, &on) < 0) {
 				err = -errno;
 				SNDMSG("TSTAMP failed\n");
-				return err;
+				goto out;
 			}
 		}
 		pcm->tstamp_type = params->tstamp_type;
 	}
-	sw_set_period_event(params, old_period_event);
 	hw->mmap_control->avail_min = params->avail_min;
 	if (hw->period_event != old_period_event) {
 		err = snd_pcm_hw_change_timer(pcm, old_period_event);
 		if (err < 0)
-			return err;
+			goto out;
 		hw->period_event = old_period_event;
 	}
-	return 0;
+ out:
+	sw_set_period_event(params, old_period_event);
+	return err;
 }
 
 static int snd_pcm_hw_channel_info(snd_pcm_t *pcm, snd_pcm_channel_info_t * info)