Re: [PATCH v2] ufs: core: fix ufshcd_abort_all racing issue

["Peter Wang (王信友)" <peter.wang@mediatek.com>]

On Thu, 2024-06-27 at 15:59 +0800, Wenchao Hao wrote:
> 
> Hi Peter, 
> 
> What is queue_num's offset of blk_mq_hw_ctx in your machine?
> 
> gdb vmlinux
> 
> (gdb) print /x (int)&((struct blk_mq_hw_ctx *)0)->queue_num
> $5 = 0x164
> 
> I read your descriptions and wondered a same race flow as you
> described
> following. But I found the offset mismatch, if the racing flow is
> correct,
> then the address accessed in blk_mq_unique_tag() should be 0x164, not
> 0x194.
> Maybe the offset is different between our machine?
> 
> What's more, if the racing flow is correct, I did not get how your
> changes
> can address this racing flow.
> 
> 

Hi Wenchao Hao,

Yes, our queue_num's offset of blk_mq_hw_ctx is 0x194.
Our kernel version is: Linux version 6.1.68
I think the offset is different by kernel version.

(gdb) print /x (int)&((struct blk_mq_hw_ctx *)0)->queue_num
$1 = 0x194

And yes, it only shorten the race window of step3 and step5.
Reduce the probability of step 4 appearing between step 3 and step 5.


Thanks.
Peter