| Message ID | 20220120132747.2348-3-christian.koenig@amd.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [1/9] dma-buf: consolidate dma_fence subclass checking | expand |
On 1/20/22 14:27, Christian König wrote: > It's not allowed to nest another dma_fence container into a dma_fence_array > or otherwise we can run into recursion. > > Warn about that when we create a dma_fence_array. > > Signed-off-by: Christian König <christian.koenig@amd.com> > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> > --- > drivers/dma-buf/dma-fence-array.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c > index 3e07f961e2f3..4bfbcb885bbc 100644 > --- a/drivers/dma-buf/dma-fence-array.c > +++ b/drivers/dma-buf/dma-fence-array.c > @@ -176,6 +176,19 @@ struct dma_fence_array *dma_fence_array_create(int num_fences, > > array->base.error = PENDING_ERROR; > > + /* dma_fence_array objects should never contain any other fence Nit: First comment line of multi-line comments shouldn't contain text. > + * containers or otherwise we run into recursion and potential kernel > + * stack overflow on operations on the dma_fence_array. > + * > + * The correct way of handling this is to flatten out the array by the > + * caller instead. > + * > + * Enforce this here by checking that we don't create a dma_fence_array > + * with any container inside. > + */ > + while (seqno--) > + WARN_ON(dma_fence_is_container(fences[seqno])); > + s/seqno/num_fences/g ? Thanks, Thomas > return array; > } > EXPORT_SYMBOL(dma_fence_array_create);
Am 21.01.22 um 08:31 schrieb Thomas Hellström: > > On 1/20/22 14:27, Christian König wrote: >> It's not allowed to nest another dma_fence container into a >> dma_fence_array >> or otherwise we can run into recursion. >> >> Warn about that when we create a dma_fence_array. >> >> Signed-off-by: Christian König <christian.koenig@amd.com> >> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> >> --- >> drivers/dma-buf/dma-fence-array.c | 13 +++++++++++++ >> 1 file changed, 13 insertions(+) >> >> diff --git a/drivers/dma-buf/dma-fence-array.c >> b/drivers/dma-buf/dma-fence-array.c >> index 3e07f961e2f3..4bfbcb885bbc 100644 >> --- a/drivers/dma-buf/dma-fence-array.c >> +++ b/drivers/dma-buf/dma-fence-array.c >> @@ -176,6 +176,19 @@ struct dma_fence_array >> *dma_fence_array_create(int num_fences, >> array->base.error = PENDING_ERROR; >> + /* dma_fence_array objects should never contain any other fence > Nit: First comment line of multi-line comments shouldn't contain text. >> + * containers or otherwise we run into recursion and potential >> kernel >> + * stack overflow on operations on the dma_fence_array. >> + * >> + * The correct way of handling this is to flatten out the array >> by the >> + * caller instead. >> + * >> + * Enforce this here by checking that we don't create a >> dma_fence_array >> + * with any container inside. >> + */ >> + while (seqno--) >> + WARN_ON(dma_fence_is_container(fences[seqno])); >> + > > s/seqno/num_fences/g ? Ah, of course! Typing to fast. Thanks, Christian. > > Thanks, > > Thomas > > > >> return array; >> } >> EXPORT_SYMBOL(dma_fence_array_create); >
diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c index 3e07f961e2f3..4bfbcb885bbc 100644 --- a/drivers/dma-buf/dma-fence-array.c +++ b/drivers/dma-buf/dma-fence-array.c @@ -176,6 +176,19 @@ struct dma_fence_array *dma_fence_array_create(int num_fences, array->base.error = PENDING_ERROR; + /* dma_fence_array objects should never contain any other fence + * containers or otherwise we run into recursion and potential kernel + * stack overflow on operations on the dma_fence_array. + * + * The correct way of handling this is to flatten out the array by the + * caller instead. + * + * Enforce this here by checking that we don't create a dma_fence_array + * with any container inside. + */ + while (seqno--) + WARN_ON(dma_fence_is_container(fences[seqno])); + return array; } EXPORT_SYMBOL(dma_fence_array_create);