diff mbox series

[v3,13/16] /dev/mem: Only set filp->f_mapping

Message ID 20201021085655.1192025-14-daniel.vetter@ffwll.ch (mailing list archive)
State New, archived
Headers show
Series follow_pfn and other iomap races | expand

Commit Message

Daniel Vetter Oct. 21, 2020, 8:56 a.m. UTC 
When we care about pagecache maintenance, we need to make sure that
both f_mapping and i_mapping point at the right mapping.

But for iomem mappings we only care about the virtual/pte side of
things, so f_mapping is enough. Also setting inode->i_mapping was
confusing me as a driver maintainer, since in e.g. drivers/gpu we
don't do that. Per Dan this seems to be copypasta from places which do
care about pagecache consistency, but not needed. Hence remove it for
slightly less confusion.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kees Cook <keescook@chromium.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: linux-mm@kvack.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: linux-media@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.com>
---
 drivers/char/mem.c | 1 -
 1 file changed, 1 deletion(-)

Comments

Dan Williams Oct. 21, 2020, 6:21 p.m. UTC | #1 
On Wed, Oct 21, 2020 at 1:57 AM Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
>
> When we care about pagecache maintenance, we need to make sure that
> both f_mapping and i_mapping point at the right mapping.
>
> But for iomem mappings we only care about the virtual/pte side of
> things, so f_mapping is enough. Also setting inode->i_mapping was
> confusing me as a driver maintainer, since in e.g. drivers/gpu we
> don't do that. Per Dan this seems to be copypasta from places which do
> care about pagecache consistency, but not needed. Hence remove it for
> slightly less confusion.
>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Jason Gunthorpe <jgg@ziepe.ca>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Jérôme Glisse <jglisse@redhat.com>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Dan Williams <dan.j.williams@intel.com>

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
diff mbox series

Patch

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index abd4ffdc8cde..5502f56f3655 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -864,7 +864,6 @@  static int open_port(struct inode *inode, struct file *filp)
 	 * revocations when drivers want to take over a /dev/mem mapped
 	 * range.
 	 */
-	inode->i_mapping = devmem_inode->i_mapping;
 	filp->f_mapping = inode->i_mapping;
 
 	return 0;