[alsa-devel] [RFC PATCH] ALSA: pcm: fix blocking while loop in snd_pcm_update_hw_ptr0()

[Srinivas Kandagatla]

From: Preetam Singh Ranawat <apranawat at codeaurora.org>

When period interrupts are disabled, while loop in snd_pcm_update_hw_ptr0()
results in the machine locking up if runtime->hw_ptr_buffer_jiffies is 0.

Validate runtime->hw_ptr_buffer_jiffies value before while loop to avoid
delta check.

Signed-off-by: Preetam Singh Ranawat <apranawat at codeaurora.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla at linaro.org>
---

This issue was noticed in Android setup from fastcapture path.

 sound/core/pcm_lib.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index d80041ea4e01..f407f6895f8a 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -341,7 +341,8 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream,
 		 * the elapsed time to detect xruns.
 		 */
 		jdelta = curr_jiffies - runtime->hw_ptr_jiffies;
-		if (jdelta < runtime->hw_ptr_buffer_jiffies / 2)
+		if ((jdelta < runtime->hw_ptr_buffer_jiffies / 2) ||
+		    !runtime->hw_ptr_buffer_jiffies)
 			goto no_delta_check;
 		hdelta = jdelta - delta * HZ / runtime->rate;
 		xrun_threshold = runtime->hw_ptr_buffer_jiffies / 2 + 1;
-- 
2.21.0