On 23/03/2024 15:52, Johannes Weiner wrote:
On Thu, Mar 14, 2024 at 01:09:57PM -0400, Johannes Weiner wrote:
Hello,
On Fri, Mar 08, 2024 at 12:32:33PM +0100, Christian König wrote:
Am 07.03.24 um 23:07 schrieb Johannes Weiner:
Lastly I went with an open loop instead of a memcpy() as I wasn't
sure if that memory is safe to address a byte at at time.
Shashank pointed out to me in private that byte access would indeed be
safe. However, after actually trying it it won't work because memcpy()
doesn't play nice with mqd being volatile:
/home/hannes/src/linux/linux/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c: In function 'amdgpu_debugfs_mqd_read':
/home/hannes/src/linux/linux/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c:550:22: warning: passing argument 1 of '__builtin_dynamic_object_size' discards 'volatil' qualifier from pointer target type [-Wdiscarded-qualifiers]
550 | memcpy(kbuf, mqd, ring->mqd_size);
So I would propose leaving the patch as-is. Shashank, does that sound
good to you?
Friendly ping :)
Shashank, is your Reviewed-by still good for this patch, given the
above?
Ah, sorry I missed this due to some parallel work, and just realized the
memcpy/volatile limitation.
I also feel the need of protecting MQD read under a lock to avoid
parallel change in MQD while we do byte-by-byte copy, but I will add
that in my to-do list.
Please feel free to use my R-b.
- Shashank
Thanks
