Re: [PATCH v6 13/14] iommu/arm-smmu-v3: Report events that belong to devices attached to vIOMMU

[Jason Gunthorpe]

On Tue, Feb 18, 2025 at 11:02:23AM -0800, Nicolin Chen wrote:
> > > > This already holds the streams_mutex across all of this, do you think
> > > > we should get rid of the vmaster_rwsem and hold the streams_mutex on
> > > > write instead?
> > > 
> > > They are per master v.s. per smmu. The latter one would make master
> > > commits/attaches exclusive, which feels unnecessary to me, although
> > > it would make the code here slightly cleaner..
> > 
> > I'd pay the cost on the attach side to have a single lock on the fault
> > side..
> 
> OK. Maybe a small patch to turn the streams_mutex to streams_rwsem?

I don't think the interrupt path is multithreaded, is it? So only 1
reader anyhow?

Jason