lkml.org 
[lkml]   [2019]   [Feb]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH 1/3] perf: convert perf_event_context.refcount to refcount_t
On Fri, Feb 01, 2019 at 03:44:38PM +0000, Reshetova, Elena wrote:
> > On Tue, Jan 29, 2019 at 01:55:32PM +0000, Reshetova, Elena wrote:
> > > > On Mon, Jan 28, 2019 at 02:27:26PM +0200, Elena Reshetova wrote:
> > > > > diff --git a/kernel/events/core.c b/kernel/events/core.c
> > > > > index 3cd13a3..a1e87d2 100644
> > > > > --- a/kernel/events/core.c
> > > > > +++ b/kernel/events/core.c
> > > > > @@ -1171,7 +1171,7 @@ static void perf_event_ctx_deactivate(struct
> > > > perf_event_context *ctx)
> > > > >
> > > > > static void get_ctx(struct perf_event_context *ctx)
> > > > > {
> > > > > - WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
> > > > > + WARN_ON(!refcount_inc_not_zero(&ctx->refcount));
> > > >
> > > > This could be refcount_inc(), remember how that already produces a WARN
> > > > when we try and increment 0.
> > >
> > > But is this true for the x86 arch-specific implementation also?
> >
> > If you use recount_inc_checked(), it will always produce the WARN(),
> > even when using the x86-specific refcount implementation.
> >
> > (this was one place I had intended to use the *_checked() forms of the
> > refcount ops).
>
> Yes, with refcount_inc_checked() it would work, but I don't like it
> that much when we have functions that behave regardless of refcount
> config. It does help for code minimization & clarity like here, but I think
> it complicates things even more: two different configs, then functions that
> do not obey configs, etc.

Sure. The main idea of having the _checked() forms was to not lose
warnings in a conversion to refcount_t, but I appreciate that people
might not like the existing warnings at all.

> Anyhow, I can change this to refcount_inc_checked(), if this is what everyone
> thinks is the best.

I'll defer to Peter.

Peter, would you prefer refcount_inc() or refcount_inc_checked() here?

Thanks,
Mark.

\
 
 \ /
  Last update: 2019-02-01 17:25    [W:0.059 / U:0.648 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site