On Jan 8, 2020, at 6:56 AM, Christian König <christian.koenig@amd.com> wrote:

Am 07.01.20 um 20:25 schrieb Tianlin Li:

Right now several architectures allow their set_memory_*() family of
functions to fail, but callers may not be checking the return values.
If set_memory_*() returns with an error, call-site assumptions may be
infact wrong to assume that it would either succeed or not succeed at
all. Ideally, the failure of set_memory_*() should be passed up the
call stack, and callers should examine the failure and deal with it.

Need to fix the callers and add the __must_check attribute. They also
may not provide any level of atomicity, in the sense that the memory
protections may be left incomplete on failure. This issue likely has a
few steps on effects architectures:
1)Have all callers of set_memory_*() helpers check the return value.
2)Add __must_check to all set_memory_*() helpers so that new uses do
not ignore the return value.
3)Add atomicity to the calls so that the memory protections aren't left
in a partial state.

This series is part of step 1. Make drm/radeon check the return value of
set_memory_*().

I'm a little hesitate merge that. This hardware is >15 years old and nobody of the developers have any system left to test this change on.

Would it be to much of a problem to just add something like: r = set_memory_*(); (void)r; /* Intentionally ignored */.

Apart from that certainly a good idea to add __must_check to the functions.

Regards,
Christian.

Tianlin Li (2):
  drm/radeon: have the callers of set_memory_*() check the return value
  drm/radeon: change call sites to handle return value properly.

 drivers/gpu/drm/radeon/r100.c        |  3 ++-
 drivers/gpu/drm/radeon/radeon.h      |  2 +-
 drivers/gpu/drm/radeon/radeon_gart.c | 22 ++++++++++++++++++----
 drivers/gpu/drm/radeon/rs400.c       |  3 ++-
 4 files changed, 23 insertions(+), 7 deletions(-)