dmaengine: pxa: fix double counting of the hw descriptors

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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: 69050f8d6d ("treewide: Replace kmalloc with kmalloc_obj for non-scalar types")
Assisted-by: Claude:claude-opus-5
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20260817-dmaengine-pxa-v1-1-850c215c1196@pengutronix.de
Link: https://patch.msgid.link/20260817-dmaengine-pxa-v2-1-f42ab0569a48@pengutronix.de
Signed-off-by: Vinod Koul <vkoul@kernel.org>

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Sascha Hauer 2026-08-17 22:44:33 +02:00 • committed by Vinod Koul

parent 9096bdc8d9

commit f6504be006

1 changed files with 2 additions and 1 deletions

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drivers/dma/pxa_dma.c

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