Re: [PATCH 01/11] misc: fastrpc: Assert held reservation lock for dma-buf mmapping

[Srinivas Kandagatla]

On 24/11/2022 18:03, Dmitry Osipenko wrote:
> On 11/24/22 20:51, Srinivas Kandagatla wrote:
> > From: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
> >
> > When userspace mmaps dma-buf's fd, the dma-buf reservation lock must be
> > held. Add locking sanity check to the dma-buf mmaping callback to ensure
> > that the locking assumption won't regress in the future.
> >
> > Suggested-by: Daniel Vetter <daniel@xxxxxxxx>
> > Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
> > Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
> > ---
> >   drivers/misc/fastrpc.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> > index 80811e852d8f..c6b9ddaa698b 100644
> > --- a/drivers/misc/fastrpc.c
> > +++ b/drivers/misc/fastrpc.c
> > @@ -6,6 +6,7 @@
> >   #include <linux/device.h>
> >   #include <linux/dma-buf.h>
> >   #include <linux/dma-mapping.h>
> > +#include <linux/dma-resv.h>
> >   #include <linux/idr.h>
> >   #include <linux/list.h>
> >   #include <linux/miscdevice.h>
> > @@ -692,6 +693,8 @@ static int fastrpc_mmap(struct dma_buf *dmabuf,
> >   	struct fastrpc_buf *buf = dmabuf->priv;
> >   	size_t size = vma->vm_end - vma->vm_start;
> >   
> > +	dma_resv_assert_held(dmabuf->resv);
> > +
> >   	return dma_mmap_coherent(buf->dev, vma, buf->virt,
> >   				 FASTRPC_PHYS(buf->phys), size);
> >   }
>
> This patch was already applied to DRM tree together with the rest of
> prerequisite dma-buf patches. IOW, it shouldn't be applied separately
> via the misc tree.
thanks, that is true.



---srini

>