On 5/12/25 13:12, Hyejeong Choi wrote: > smp_store_mb() inserts memory barrier after storing operation. > It is different with what the comment is originally aiming so Null > pointer dereference can be happened if memory update is reordered. > > Signed-off-by: Hyejeong Choi <hjeong.c...@samsung.com> > --- > drivers/dma-buf/dma-resv.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c > index 5f8d010516f0..52af5c7430da 100644 > --- a/drivers/dma-buf/dma-resv.c > +++ b/drivers/dma-buf/dma-resv.c > @@ -320,8 +320,9 @@ void dma_resv_add_fence(struct dma_resv *obj, struct > dma_fence *fence, > count++; > > dma_resv_list_set(fobj, i, fence, usage); > - /* pointer update must be visible before we extend the num_fences */ > - smp_store_mb(fobj->num_fences, count); > + /* fence update must be visible before we extend the num_fences */ > + smp_wmb(); > + WRITE_ONCE(fobj->num_fences, count);
The WRITE_ONCE isn't necessary since smp_wmb() implies a compiler barrier, but apart from that really good catch. Can you modify the patch and re-send? I will be pushing it to -fixes ASAP. Regards, Christian. > } > EXPORT_SYMBOL(dma_resv_add_fence); > > >
