[PATCH 2/2] ALSA: memalloc: Use coherent DMA allocation for fallback again
Takashi Iwai
tiwai at suse.de
Tue Jan 24 10:27:44 CET 2023
We switched the memory allocation for fallback cases in the noncontig
type to use the standard alloc_pages*() at the commit a8d302a0b770
("ALSA: memalloc: Revive x86-specific WC page allocations again"),
while we used the dma_alloc_coherent() in the past. The reason was
that the page address retrieved from the virtual pointer returned from
dma_alloc_coherent() can't be used with IOMMU systems. Meanwhile, we
explicitly disabled the fallback allocation for IOMMU systems at the
commit 9736a325137b ("ALSA: memalloc: Don't fall back for SG-buffer
with IOMMU") after the commit above; that is, the usage of
dma_alloc_coherent() should be OK again.
Now, we've received reports that the current fallback page allocation
caused a regression on Xen (and maybe other) systems; the sound
disappear partially or completely. So it's time to take back to
dma_alloc_coherent().
This patch switches back to the dma_alloc_coherent() for the fallback
allocations. Unlike the previous implementation, the allocation is
implemented in a more optimized way to try larger chunks. Also, the
proper DMA address from the dma_alloc_coherent() is returned.
The page count for the page chunk is stored in the lower bits of the
first page address. The address is masked and re-calculated at
get_addr memalloc ops in return.
Fixes: a8d302a0b770 ("ALSA: memalloc: Revive x86-specific WC page allocations again")
Fixes: 9736a325137b ("ALSA: memalloc: Don't fall back for SG-buffer with IOMMU")
Reported-and-tested-by: Marek Marczykowski-Górecki <marmarek at invisiblethingslab.com>
Link: https://lore.kernel.org/r/87tu256lqs.wl-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
sound/core/memalloc.c | 61 ++++++++++++++++++++++++++++++++++---------
1 file changed, 49 insertions(+), 12 deletions(-)
diff --git a/sound/core/memalloc.c b/sound/core/memalloc.c
index 30c9ad192986..5fe21c0080dc 100644
--- a/sound/core/memalloc.c
+++ b/sound/core/memalloc.c
@@ -720,17 +720,31 @@ static const struct snd_malloc_ops snd_dma_sg_wc_ops = {
struct snd_dma_sg_fallback {
size_t count;
struct page **pages;
+ /* DMA address array; the first page contains #pages in ~PAGE_MASK */
+ dma_addr_t *addrs;
};
static void __snd_dma_sg_fallback_free(struct snd_dma_buffer *dmab,
struct snd_dma_sg_fallback *sgbuf)
{
- bool wc = dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK;
- size_t i;
-
- for (i = 0; i < sgbuf->count && sgbuf->pages[i]; i++)
- do_free_pages(page_address(sgbuf->pages[i]), PAGE_SIZE, wc);
+ size_t i, size;
+
+ if (sgbuf->pages && sgbuf->addrs) {
+ i = 0;
+ while (i < sgbuf->count) {
+ if (!sgbuf->pages[i] || !sgbuf->addrs[i])
+ break;
+ size = sgbuf->addrs[i] & ~PAGE_MASK;
+ if (WARN_ON(!size))
+ break;
+ dma_free_coherent(dmab->dev.dev, size << PAGE_SHIFT,
+ page_address(sgbuf->pages[i]),
+ sgbuf->addrs[i] & PAGE_MASK);
+ i += size;
+ }
+ }
kvfree(sgbuf->pages);
+ kvfree(sgbuf->addrs);
kfree(sgbuf);
}
@@ -739,9 +753,9 @@ static void *snd_dma_sg_fallback_alloc(struct snd_dma_buffer *dmab, size_t size)
struct snd_dma_sg_fallback *sgbuf;
struct page **pagep, *curp;
size_t chunk, npages;
+ dma_addr_t *addrp;
dma_addr_t addr;
void *p;
- bool wc = dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK;
sgbuf = kzalloc(sizeof(*sgbuf), GFP_KERNEL);
if (!sgbuf)
@@ -749,14 +763,16 @@ static void *snd_dma_sg_fallback_alloc(struct snd_dma_buffer *dmab, size_t size)
size = PAGE_ALIGN(size);
sgbuf->count = size >> PAGE_SHIFT;
sgbuf->pages = kvcalloc(sgbuf->count, sizeof(*sgbuf->pages), GFP_KERNEL);
- if (!sgbuf->pages)
+ sgbuf->addrs = kvcalloc(sgbuf->count, sizeof(*sgbuf->addrs), GFP_KERNEL);
+ if (!sgbuf->pages || !sgbuf->addrs)
goto error;
pagep = sgbuf->pages;
- chunk = size;
+ addrp = sgbuf->addrs;
+ chunk = (PAGE_SIZE - 1) << PAGE_SHIFT; /* to fit in low bits in addrs */
while (size > 0) {
chunk = min(size, chunk);
- p = do_alloc_pages(dmab->dev.dev, chunk, &addr, wc);
+ p = dma_alloc_coherent(dmab->dev.dev, chunk, &addr, DEFAULT_GFP);
if (!p) {
if (chunk <= PAGE_SIZE)
goto error;
@@ -768,17 +784,25 @@ static void *snd_dma_sg_fallback_alloc(struct snd_dma_buffer *dmab, size_t size)
size -= chunk;
/* fill pages */
npages = chunk >> PAGE_SHIFT;
+ *addrp = npages; /* store in lower bits */
curp = virt_to_page(p);
- while (npages--)
+ while (npages--) {
*pagep++ = curp++;
+ *addrp++ |= addr;
+ addr += PAGE_SIZE;
+ }
}
p = vmap(sgbuf->pages, sgbuf->count, VM_MAP, PAGE_KERNEL);
if (!p)
goto error;
+
+ if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK)
+ set_pages_array_wc(sgbuf->pages, sgbuf->count);
+
dmab->private_data = sgbuf;
/* store the first page address for convenience */
- dmab->addr = snd_sgbuf_get_addr(dmab, 0);
+ dmab->addr = sgbuf->addrs[0] & PAGE_MASK;
return p;
error:
@@ -788,10 +812,23 @@ static void *snd_dma_sg_fallback_alloc(struct snd_dma_buffer *dmab, size_t size)
static void snd_dma_sg_fallback_free(struct snd_dma_buffer *dmab)
{
+ struct snd_dma_sg_fallback *sgbuf = dmab->private_data;
+
vunmap(dmab->area);
+ if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK)
+ set_pages_array_wb(sgbuf->pages, sgbuf->count);
__snd_dma_sg_fallback_free(dmab, dmab->private_data);
}
+static dma_addr_t snd_dma_sg_fallback_get_addr(struct snd_dma_buffer *dmab,
+ size_t offset)
+{
+ struct snd_dma_sg_fallback *sgbuf = dmab->private_data;
+ size_t index = offset >> PAGE_SHIFT;
+
+ return (sgbuf->addrs[index] & PAGE_MASK) | (offset & ~PAGE_MASK);
+}
+
static int snd_dma_sg_fallback_mmap(struct snd_dma_buffer *dmab,
struct vm_area_struct *area)
{
@@ -806,8 +843,8 @@ static const struct snd_malloc_ops snd_dma_sg_fallback_ops = {
.alloc = snd_dma_sg_fallback_alloc,
.free = snd_dma_sg_fallback_free,
.mmap = snd_dma_sg_fallback_mmap,
+ .get_addr = snd_dma_sg_fallback_get_addr,
/* reuse vmalloc helpers */
- .get_addr = snd_dma_vmalloc_get_addr,
.get_page = snd_dma_vmalloc_get_page,
.get_chunk_size = snd_dma_vmalloc_get_chunk_size,
};
--
2.35.3
More information about the Alsa-devel
mailing list