Re: [Xen-devel] missing lock in percpu_rwlock? (Was: Re: New Defects reported by Coverity Scan for XenProject)

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Wed, 2016-02-03 at 10:50 +0000, Andrew Cooper wrote:
> On 03/02/16 10:45, Ian Campbell wrote:
> > On Tue, 2016-02-02 at 20:23 -0800, scan-admin@xxxxxxxxxxxx wrote:
> > > * CID 1351223:ÂÂConcurrent data access violationsÂÂ(MISSING_LOCK)
> > > /xen/include/xen/spinlock.h: 362 in _percpu_write_unlock()
> > Coverity seems to think this is new in 41b0aa569adb..9937763265d,
> > presumably due to 
> > 
> > commit f9dd43dddc0a31a4343a58072935c1b5c0cbbee
> > Author: Malcolm Crossley <malcolm.crossley@xxxxxxxxxx>
> > Date:ÂÂÂFri Jan 22 16:04:41 2016 +0100
> > 
> > ÂÂÂÂrwlock: add per-cpu reader-writer lock infrastructure
> 
> Expected behaviour.ÂÂwriter_activating is expected to only be written
> under lock, but read without lock.

I suppose this is something we should eventually model?

Would you typically mark this as "False positive" or "Intentional"?

I just marked a couple of libxl ones about taking ctx->lock (which is
recursive) twice as "False positive", but perhaps "Intentional" is the
correct designation there?

Ian.


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