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

From: John Garry
Date: Mon Oct 19 2015 - 10:12:19 EST


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

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