> From: Christian König <christian.koenig@xxxxxxx>
> Sent: Wednesday, August 18, 2021 2:10 PM
> To: Sa, Nuno <Nuno.Sa@xxxxxxxxxx>; linaro-mm-sig@xxxxxxxxxxxxxxxx;
> dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-media@xxxxxxxxxxxxxxx
> Cc: Rob Clark <rob@xxxxxx>; Sumit Semwal
> <sumit.semwal@xxxxxxxxxx>
> Subject: Re: [PATCH] dma-buf: return -EINVAL if dmabuf object is
> NULL
>
> [External]
>
> To be honest I think the if(WARN_ON(!dmabuf)) return -EINVAL
> handling
> here is misleading in the first place.
>
> Returning -EINVAL on a hard coding error is not good practice and
> should
> probably be removed from the DMA-buf subsystem in general.
Would you say to just return 0 then? I don't think that having the
dereference is also good..
I used -EINVAL to be coherent with the rest of the code.
- Nuno Sá
> Christian.
>
> Am 18.08.21 um 13:58 schrieb Nuno Sá:
> > On top of warning about a NULL object, we also want to return with a
> > proper error code (as done in 'dma_buf_begin_cpu_access()').
> Otherwise,
> > we will get a NULL pointer dereference.
> >
> > Fixes: fc13020e086b ("dma-buf: add support for kernel cpu access")
> > Signed-off-by: Nuno Sá <nuno.sa@xxxxxxxxxx>
> > ---
> > drivers/dma-buf/dma-buf.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-
> buf.c
> > index 63d32261b63f..8ec7876dd523 100644
> > --- a/drivers/dma-buf/dma-buf.c
> > +++ b/drivers/dma-buf/dma-buf.c
> > @@ -1231,7 +1231,8 @@ int dma_buf_end_cpu_access(struct
> dma_buf *dmabuf,
> > {
> > int ret = 0;
> >
> > - WARN_ON(!dmabuf);
> > + if (WARN_ON(!dmabuf))
> > + return -EINVAL;
> >
> > might_lock(&dmabuf->resv->lock.base);
> >
