Re: [PATCH 13/25] scsi: hisi_sas: add path from phyup irq to SAS framework

John Garry
2015-10-19T14:11:47Z

On 16/10/2015 14:36, Arnd Bergmann wrote:
> On Friday 16 October 2015 14:29:55 John Garry wrote:
>>
>> It could be considered.
>>
>> A potential issue I see is with hisi_sas_control_phy() for
>> PHY_FUNC_HARD_RESET: this allocates a hisi_sas_wq struct and processes
>> the reset in the queue work. When we re-enable the phy for the reset,
>> the phyup irq will want to use the same hisi_sas_wq struct which may be
>> in use.
>>
>> hisi_sas_control_phy() is added in 23/35.
>
> I'd have to review more closely, but I think that's fine, as this
> is how most work queues are used: you can queue the same function
> multiple times, and it's guaranteed to run at least once after
> the last queue, so if you queue it while it's already running,
> it will be called again, otherwise it won't.
>
> Arnd
>
> .
>
In the scenario I described the issue is not that the second call to
queue the work function is lost. The problem is that when we setup the
second call we may overwrite elements of the phy's hisi_sas_wq struct
which may be still being referenced in the work function for the first call.

Regards,
John