Re: [PATCH 4.4 52/97] mtip32xx: use runtime tag to initialize command header

[Ben Hutchings]

On Fri, 2018-03-23 at 10:54 +0100, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.ÂÂIf anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Ming Lei <ming.lei@xxxxxxxxxx>
> 
> 
> [ Upstream commit a4e84aae8139aca9fbfbced1f45c51ca81b57488 ]
> 
> mtip32xx supposes that 'request_idx' passed to .init_request()
> is tag of the request, and use that as request's tag to initialize
> command header.
> 
> After MQ IO scheduler is in, request tag assigned isn't same with
> the request index anymore, so cause strange hardware failure on
> mtip32xx, even whole system panic is triggered.
[...]

MQ IO schedulers were introduced in 4.11, so this shouldn't be needed
in older branches.  It also causes a performance regression (fixed
upstream).  Please revert this for 4.4 and 4.9.

Ben.

-- 
Ben Hutchings
Software Developer, Codethink Ltd.