[PATCH] ALSA: memalloc: prefer dma_mapping_error() over explicit address checking

[PATCH] ALSA: memalloc: prefer dma_mapping_error() over explicit address checking

[Fedor Pchelkin]

With CONFIG_DMA_API_DEBUG enabled, the following warning is observed:

DMA-API: snd_hda_intel 0000:03:00.1: device driver failed to check map error[device address=0x00000000ffff0000] [size=20480 bytes] [mapped as single]
WARNING: CPU: 28 PID: 2255 at kernel/dma/debug.c:1036 check_unmap+0x1408/0x2430
CPU: 28 UID: 42 PID: 2255 Comm: wireplumber Tainted: G  W L  6.12.0-10-133577cad6bf48e5a7848c4338124081393bfe8a+ #759
debug_dma_unmap_page+0xe9/0xf0
snd_dma_wc_free+0x85/0x130 [snd_pcm]
snd_pcm_lib_free_pages+0x1e3/0x440 [snd_pcm]
snd_pcm_common_ioctl+0x1c9a/0x2960 [snd_pcm]
snd_pcm_ioctl+0x6a/0xc0 [snd_pcm]
...

Check for returned DMA addresses using specialized dma_mapping_error()
helper which is generally recommended for this purpose by
Documentation/core-api/dma-api.rst.

Fixes: c880a5146642 ("ALSA: memalloc: Use proper DMA mapping API for x86 WC buffer allocations")
Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Closes: https://lore.kernel.org/r/CABXGCsNB3RsMGvCucOy3byTEOxoc-Ys+zB_HQ=Opb_GhX1ioDA@mail.gmail.com/
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
---
Decided not to wrap long dmesg lines. If it looks really ugly for the
commit message, please feel free to adjust them to the standards.

 sound/core/memalloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/core/memalloc.c b/sound/core/memalloc.c
index 13b71069ae18..b3853583d2ae 100644
--- a/sound/core/memalloc.c
+++ b/sound/core/memalloc.c
@@ -505,7 +505,7 @@ static void *snd_dma_wc_alloc(struct snd_dma_buffer *dmab, size_t size)
 	if (!p)
 		return NULL;
 	dmab->addr = dma_map_single(dmab->dev.dev, p, size, DMA_BIDIRECTIONAL);
-	if (dmab->addr == DMA_MAPPING_ERROR) {
+	if (dma_mapping_error(dmab->dev.dev, dmab->addr)) {
 		do_free_pages(dmab->area, size, true);
 		return NULL;
 	}
-- 
2.39.5

Re: [PATCH] ALSA: memalloc: prefer dma_mapping_error() over explicit address checking

[Takashi Iwai]

On Thu, 19 Dec 2024 21:33:45 +0100,
Fedor Pchelkin wrote:
> 
> With CONFIG_DMA_API_DEBUG enabled, the following warning is observed:
> 
> DMA-API: snd_hda_intel 0000:03:00.1: device driver failed to check map error[device address=0x00000000ffff0000] [size=20480 bytes] [mapped as single]
> WARNING: CPU: 28 PID: 2255 at kernel/dma/debug.c:1036 check_unmap+0x1408/0x2430
> CPU: 28 UID: 42 PID: 2255 Comm: wireplumber Tainted: G  W L  6.12.0-10-133577cad6bf48e5a7848c4338124081393bfe8a+ #759
> debug_dma_unmap_page+0xe9/0xf0
> snd_dma_wc_free+0x85/0x130 [snd_pcm]
> snd_pcm_lib_free_pages+0x1e3/0x440 [snd_pcm]
> snd_pcm_common_ioctl+0x1c9a/0x2960 [snd_pcm]
> snd_pcm_ioctl+0x6a/0xc0 [snd_pcm]
> ...
> 
> Check for returned DMA addresses using specialized dma_mapping_error()
> helper which is generally recommended for this purpose by
> Documentation/core-api/dma-api.rst.
> 
> Fixes: c880a5146642 ("ALSA: memalloc: Use proper DMA mapping API for x86 WC buffer allocations")
> Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
> Closes: https://lore.kernel.org/r/CABXGCsNB3RsMGvCucOy3byTEOxoc-Ys+zB_HQ=Opb_GhX1ioDA@mail.gmail.com/
> Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
> ---
> Decided not to wrap long dmesg lines. If it looks really ugly for the
> commit message, please feel free to adjust them to the standards.

It looks fine, so applied now.  Thanks!


Takashi