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, 5 deletions

diff --git a/sound/soc/nuc900/nuc900-pcm.c b/sound/soc/nuc900/nuc900-pcm.c
index c894ff0f258..f588ee45b4f 100644
--- a/sound/soc/nuc900/nuc900-pcm.c
+++ b/sound/soc/nuc900/nuc900-pcm.c
@@ -314,16 +314,15 @@ static void nuc900_dma_free_dma_buffers(struct snd_pcm *pcm)
 	snd_pcm_lib_preallocate_free_for_all(pcm);
 }
 
-static u64 nuc900_pcm_dmamask = DMA_BIT_MASK(32);
 static int nuc900_dma_new(struct snd_soc_pcm_runtime *rtd)
 {
 	struct snd_card *card = rtd->card->snd_card;
 	struct snd_pcm *pcm = rtd->pcm;
+	int ret;
 
-	if (!card->dev->dma_mask)
-		card->dev->dma_mask = &nuc900_pcm_dmamask;
-	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;
 
 	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV,
 		card->dev, 4 * 1024, (4 * 1024) - 1);