DMA-API: sound: fix dma mask handling in a lot of drivers

This code sequence is unsafe in modules:

static u64 mask = DMA_BIT_MASK(something);
...
	if (!dev->dma_mask)
		dev->dma_mask = &mask;

as if a module is reloaded, the mask will be pointing at the original
module's mask address, and this can lead to oopses.  Moreover, they
all follow this with:

	if (!dev->coherent_dma_mask)
		dev->coherent_dma_mask = mask;

where 'mask' is the same value as the statically defined mask, and this
bypasses the architecture's check on whether the DMA mask is possible.

Fix these issues by using the new dma_coerce_coherent_and_mask()
function.

Acked-by: Mark Brown <broonie@linaro.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 4 insertions, 8 deletions

diff --git a/sound/soc/jz4740/jz4740-pcm.c b/sound/soc/jz4740/jz4740-pcm.c
index 710059292318..1d7ef28585e1 100644
--- a/sound/soc/jz4740/jz4740-pcm.c
+++ b/sound/soc/jz4740/jz4740-pcm.c
@@ -297,19 +297,15 @@ static void jz4740_pcm_free(struct snd_pcm *pcm)
         }
 }
 
-static u64 jz4740_pcm_dmamask = DMA_BIT_MASK(32);
-
 static int jz4740_pcm_new(struct snd_soc_pcm_runtime *rtd)
 {
         struct snd_card *card = rtd->card->snd_card;
         struct snd_pcm *pcm = rtd->pcm;
-        int ret = 0;
-
-        if (!card->dev->dma_mask)
-                card->dev->dma_mask = &jz4740_pcm_dmamask;
+        int ret;
 
-        if (!card->dev->coherent_dma_mask)
-                card->dev->coherent_dma_mask = DMA_BIT_MASK(32);
+        ret = dma_coerce_mask_and_coherent(card->dev, DMA_BIT_MASK(32));
+        if (ret)
+                return ret;
 
         if (pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream) {
                 ret = jz4740_pcm_preallocate_dma_buffer(pcm,