From a55eaf177a36f7789eec0985a7edd00fe7353d90 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Tue, 5 Nov 2019 20:10:06 +0100
Subject: [PATCH] ALSA: pcm: Warn if doubly preallocated
Git-commit: a55eaf177a36f7789eec0985a7edd00fe7353d90
Patch-mainline: v5.5-rc1
References: jsc#SLE-16518

Warn if snd_pcm_lib_preallocate_pages*() is applied to the stream that
has already the preallocated buffers and skip the allocation.  It's a
clearly a driver bug.

Link: https://lore.kernel.org/r/20191105191007.18150-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

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

diff --git a/sound/core/pcm_memory.c b/sound/core/pcm_memory.c
index 7600dcdf5fd4..19407f79b638 100644
--- a/sound/core/pcm_memory.c
+++ b/sound/core/pcm_memory.c
@@ -221,6 +221,8 @@ void snd_pcm_lib_preallocate_pages(struct snd_pcm_substream *substream,
 				  int type, struct device *data,
 				  size_t size, size_t max)
 {
+	if (snd_BUG_ON(substream->dma_buffer.dev.type))
+		return;
 	substream->dma_buffer.dev.type = type;
 	substream->dma_buffer.dev.dev = data;
 	snd_pcm_lib_preallocate_pages1(substream, size, max);
-- 
2.16.4