On Mon, May 08, 2023 at 12:14:54PM -0400, Theodore Ts'o wrote: > On Mon, May 08, 2023 at 03:13:37PM +0000, Tudor Ambarus wrote: > > If @buffer is NULL, no operation is performed for kvfree(buffer), > > remove superfluous check. > > > > Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxx> > > I was looking at this just a few weeks ago, and I couldn't find any > actual *documentation* that it was safe to call vfree(NIILL) or > kvfree(NULL). The problem is there are a lot of architecture-specific > functions, and unlike with kfree() there is no top-level "if (ptr == > NULL) return;" in the top-level vfree() and kvfree(). There doesn't need to be in kvfree(). is_vmalloc_addr() returns 'false' for NULL, so it calls kfree(), which as you note has an explicit check for ZERO_OR_NULL_PTR(). is_vmalloc_addr() also returns false for the ZERO pointer, fwiw. I agree that this should be explicitly documented as allowed, since it's not reasonable to expect users to dig through these functions to verify that such a change is safe.
