Re: [PATCH] scsi: ufs: revert HPB support

Bart Van Assche
2021-10-25T16:12:17Z

On 10/21/21 11:20 PM, Christoph Hellwig wrote:
> The HPB support added this merge window is fundanetally flawed as it
> uses blk_insert_cloned_request to insert a cloned request onto the same
> queue as the one that the original request came from, leading to all
> kinds of issues in blk-mq accounting (in addition to this API being
> a special case for dm-mpath that should not see other users).

I do not agree with removing the UFS HPB code from the upstream kernel
at this time.

One of the HPB users promised to look into removing the
blk_insert_cloned_request() call from the UFS HPB code. Shouldn't that
person be given the chance to come up with a patch before removal of the
UFS HPB code is considered?

Additionally, removing the UFS HPB code from the upstream kernel won't
affect UFS users much. As far as I know all HPB users use Android. UFS
HPB is supported by Android 12 and will also be supported by Android 13.
Whether or not this patch is goes upstream won't affect the Android
kernel. I am not aware of any plans to make any changes in the Android
kernel UFS HPB code if this patch would be integrated in the upstream
kernel.

Bart.