Re: [PATCH 00/11] scsi: libsas: Remove in_interrupt() check

[John Garry]

On 22/12/2020 12:30, Jason Yan wrote:
> >      return event;
> >
> >
> > So default for phy->ha->event_thres is 32, and I can't imagine that 
>
> The default value is 1024.

Ah, 32 is the minimum allowed set via sysfs.

> > anyone has ever reconfigured this via sysfs or even required a value 
> > that large. Maybe Jason (cc'ed) knows better. It's an arbitrary value 
> > to say that the PHY is malfunctioning. I do note that there is the 
> > circular path sas_alloc_event() -> sas_notify_phy_event() -> 
> > sas_alloc_event() there also.
> >
> > Anyway, if the 32x event memories were per-allocated, maybe there is a 
> > clean method to manage this memory, which even works in atomic 
> > context, so we could avoid this rework (ignoring the context bugs you 
> > reported for a moment). I do also note that the sas_event_cache size 
> > is not huge.
>
> Pre-allocated memory is an option.(Which we have tried at the very 
> beginnig by Wang Yijing.)

Right, I remember this, but I think the concern was having a proper 
method to manage this pre-allocated memory then. And same problem now.

> Or directly use GFP_ATOMIC is maybe better than passing flags from lldds.

I think that if we don't really need this, then should not use it.

Thanks,
John