Messages in this thread | | | Subject | Re: [PATCH v2 1/2] libsas: Don't process sas events in static works | From | John Garry <> | Date | Wed, 14 Jun 2017 14:08:16 +0100 |
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On 14/06/2017 10:04, wangyijing wrote: >>> static void notify_ha_event(struct sas_ha_struct *sas_ha, enum ha_event event) >>> >> { >>> >> + struct sas_ha_event *ev; >>> >> + >>> >> BUG_ON(event >= HA_NUM_EVENTS); >>> >> >>> >> - sas_queue_event(event, &sas_ha->pending, >>> >> - &sas_ha->ha_events[event].work, sas_ha); >>> >> + ev = kzalloc(sizeof(*ev), GFP_ATOMIC); >>> >> + if (!ev) >>> >> + return; >> > GFP_ATOMIC allocations can fail and then no events will be queued *and* we >> > don't report the error back to the caller. >> > > Yes, it's really a problem, but I don't find a better solution, do you have some suggestion ? >
Dan raised an issue with this approach, regarding a malfunctioning PHY which spews out events. I still don't think we're handling it safely. Here's the suggestion: - each asd_sas_phy owns a finite-sized pool of events - when the event pool becomes exhausted, libsas stops queuing events (obviously) and disables the PHY in the LLDD - upon attempting to re-enable the PHY from sysfs, libsas first checks that the pool is still not exhausted
If you cannot find a good solution, then let us know and we can help.
John
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