pxad_alloc_desc() was converted from
kzalloc(struct_size(sw_desc, hw_desc, nb_hw_desc), GFP_NOWAIT)
to kzalloc_flex(), which sets the __counted_by() counter sw_desc->nb_desc
itself - but only where the compiler has __builtin_counted_by_ref(), so
from gcc 15.1 or clang 22.1 on. The loop below it still increments
nb_desc, which makes it come out doubled there and correct elsewhere.
nb_desc is what pxad_free_desc() iterates over and what
set_updater_desc() indexes from, so set it explicitly and drop the
increment. The error path has to lower it to the number of descriptors
allocated so far, otherwise pxad_free_desc() would free entries that were
never allocated.
Fixes: 69050f8d6d075 ("treewide: Replace kmalloc with kmalloc_obj for
non-scalar types")
Assisted-by: Claude:claude-opus-5
Signed-off-by: Sascha Hauer <[email protected]>
---
pxad_alloc_desc() was converted from
kzalloc(struct_size(sw_desc, hw_desc, nb_hw_desc), GFP_NOWAIT)
to kzalloc_flex(). hw_desc[] is annotated with __counted_by(nb_desc), so
__alloc_flex() now initializes sw_desc->nb_desc to nb_hw_desc itself.
The loop below it still increments nb_desc for every descriptor it
allocates though, so nb_desc ends up being twice the number of
descriptors that are actually there.
Drop the now redundant increment. The error path has to set nb_desc to
the number of descriptors allocated so far, otherwise pxad_free_desc()
would free entries that were never allocated.
---
Changes in v2:
- assign sw_desc->nb_desc manually as it is only automatically assigned
for compilers supporting __builtin_counted_by_ref()
- Link to v1:
https://lore.kernel.org/r/[email protected]
---
drivers/dma/pxa_dma.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c
index fa2ee0b3e09f8..fc43124fefa89 100644
--- a/drivers/dma/pxa_dma.c
+++ b/drivers/dma/pxa_dma.c
@@ -744,6 +744,7 @@ pxad_alloc_desc(struct pxad_chan *chan, unsigned int
nb_hw_desc)
sw_desc = kzalloc_flex(*sw_desc, hw_desc, nb_hw_desc, GFP_NOWAIT);
if (!sw_desc)
return NULL;
+ sw_desc->nb_desc = nb_hw_desc;
sw_desc->desc_pool = chan->desc_pool;
for (i = 0; i < nb_hw_desc; i++) {
@@ -752,10 +753,10 @@ pxad_alloc_desc(struct pxad_chan *chan, unsigned int
nb_hw_desc)
dev_err(&chan->vc.chan.dev->device,
"%s(): Couldn't allocate the %dth hw_desc from
dma_pool %p\n",
__func__, i, sw_desc->desc_pool);
+ sw_desc->nb_desc = i;
goto err;
}
- sw_desc->nb_desc++;
sw_desc->hw_desc[i] = desc;
if (i == 0)
---
base-commit: 8d3ae59288f1e7d58d76558a6ee96d533bc5019f
change-id: 20260817-dmaengine-pxa-64152bb34313
Best regards,
--
Sascha Hauer <[email protected]>
