Re: [PATCH] dmaengine: ti: Fix a potential under memory allocation issue in edma_setup_from_hw()

[Christophe JAILLET]

Le 28/05/2022 à 11:33, Péter Ujfalusi a écrit :
> On 21/05/2022 20:26, Christophe JAILLET wrote:
> > If the 'queue_priority_mapping' is not provided, we need to allocate the
> > correct amount of memory. Each entry takes 2 s8, so actually less memory
> > than needed is allocated.
> >
> > Update the size of each entry when the memory is devm_kcalloc'ed.
> >
> > Fixes: 6d10c3950bf4 ("ARM: edma: Get IP configuration from HW (number of channels, tc, etc)")
> > Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> > ---
> > Note that the devm_kcalloc() in edma_xbar_event_map() looks also spurious.
> > However, this looks fine to me because of the 'nelm >>= 1;' before the
> > 'for' loop.
>
> This has been deprecated ever since we have moved to dma router to
> handle the xbar for various TI platforms, but by the looks it kida looks
> bogus in a same way.

This one is correct, IIUC.

There is an extra ">> 1" before the loop. (see [1]).

CJ

[1]: 
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/dma/ti/edma.c#n2173

> > ---
> >   drivers/dma/ti/edma.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/dma/ti/edma.c b/drivers/dma/ti/edma.c
> > index 3ea8ef7f57df..f313e2cf542c 100644
> > --- a/drivers/dma/ti/edma.c
> > +++ b/drivers/dma/ti/edma.c
> > @@ -2121,7 +2121,7 @@ static int edma_setup_from_hw(struct device *dev, struct edma_soc_info *pdata,
> >   	 * priority. So Q0 is the highest priority queue and the last queue has
> >   	 * the lowest priority.
> >   	 */
> > -	queue_priority_map = devm_kcalloc(dev, ecc->num_tc + 1, sizeof(s8),
> > +	queue_priority_map = devm_kcalloc(dev, ecc->num_tc + 1, sizeof(s8) * 2,
> >   					  GFP_KERNEL);
> >   	if (!queue_priority_map)
> >   		return -ENOMEM;