linux-kernel - [PATCH 3.2 015/153] ALSA: seq: correctly detect input buffer overflow

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Date:   Wed, 30 May 2018 11:52:41 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Adam Goode" <agoode@...gle.com>,
        "Takashi Iwai" <tiwai@...e.de>
Subject: [PATCH 3.2 015/153] ALSA: seq: correctly detect input buffer overflow

3.2.102-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Adam Goode <agoode@...gle.com>

commit 21fd3e956ee8a307a06bc6e095f5767a00eb2a7e upstream.

snd_seq_event_dup returns -ENOMEM in some buffer-full conditions,
but usually returns -EAGAIN. Make -EAGAIN trigger the overflow
condition in snd_seq_fifo_event_in so that the fifo is cleared
and -ENOSPC is returned to userspace as stated in the alsa-lib docs.

Signed-off-by: Adam Goode <agoode@...gle.com>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 sound/core/seq/seq_fifo.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/sound/core/seq/seq_fifo.c
+++ b/sound/core/seq/seq_fifo.c
@@ -127,7 +127,7 @@ int snd_seq_fifo_event_in(struct snd_seq
 	snd_use_lock_use(&f->use_lock);
 	err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL); /* always non-blocking */
 	if (err < 0) {
-		if (err == -ENOMEM)
+		if ((err == -ENOMEM) || (err == -EAGAIN))
 			atomic_inc(&f->overflow);
 		snd_use_lock_free(&f->use_lock);
 		return err;