[PATCH v10 2/2] ufs: core: requeue aborted request

[Peter Wang (王信友)]

On Wed, 2024-10-09 at 11:06 -0700, Bart Van Assche wrote:
>  	 
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> On 10/8/24 7:17 PM, Peter Wang (王信友) wrote:
> > Yes, this patch is only for MCQ mode, because only MCQ mode
> > receives OCS: ABORTED, right? This patch doesn't modify
> > any of the Legacy mode flows, does it?
> 
> Agreed. What I mentioned in my email is an existing bug in the legacy
> flow for ufshcd_abort_all().
> 
> > Furthermore, even if there is an issue with Legacy mode, it
> > should be addressed by a separate patch, not by this one, which is
> > intended to resolve the MCQ mode issue. We shouldn't mix two
> > different issues together, don't you agree?
> 
> Let's proceed with this patch series and let's address what I brought
> up in my email separately.
> 
> With the current approach for error handling in the UFS driver,
> anyone
> who wants to verify or modify ufshcd_try_to_abort_task() has to
> consider
> all possible interleavings of ufshcd_try_to_abort_task() and the
> completion path (ufshcd_compl_one_cqe()). That's an unnecessary
> burden
> on UFS driver contributors. Additionally, this is error-prone. This
> applies to both modes (legacy and MCQ). I know of reports of sporadic
> crashes in legacy mode related to UFS error handling. I'm wondering
> whether these are perhaps the result of the issue I mentioned in a
> previous email. Anyway, I will look further into this myself as soon
> as
> I have the time.
> 
> Thanks,
> 
> Bart.

Hi Bart,

Thank you for your review.
 
I currently cannot see the issue of duplicate releases in 
legacy SDB mode. ufshcd_try_to_abort_task() will directly 
reset if it fails. It is only in the case of success that 
we need to consider the possibility of ufshcd_compl_one_cqe. 
I believe the original design flow has already taken this 
into account, which is why there is protection with 
outstanding_lock/cq_lock. Perhaps we can wait for an actual 
example to occur before making corrections. Even if there 
is an issue, I think the probability should be very low, 
because the flow for legacy SDB mode has been in use 
for several years.

Thank you again for your review.

Thanks
Peter