Message-ID: <1363101972.24558.3.camel@laptop>
Subject: Re: [PATCHv3] perf: Fix vmalloc ring buffer free function
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Jiri Olsa <jolsa@redhat.com>
Cc: linux-kernel@vger.kernel.org, Corey Ashford <cjashfor@linux.vnet.ibm.com>,
        Frederic Weisbecker <fweisbec@gmail.com>, Ingo Molnar <mingo@elte.hu>,
        Namhyung Kim <namhyung@kernel.org>, Paul Mackerras <paulus@samba.org>,
        Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Tue, 12 Mar 2013 16:26:12 +0100
In-Reply-To: <20130312135219.GA32001@krava.brq.redhat.com>
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On Tue, 2013-03-12 at 14:52 +0100, Jiri Olsa wrote:
> > @@ -373,7 +373,7 @@ struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
> >       rb->user_page = all_buf;
> >       rb->data_pages[0] = all_buf + PAGE_SIZE;
> >       rb->page_order = ilog2(nr_pages);
> > -     rb->nr_pages = 1;
> > +     rb->nr_pages = nr_pages;
> >  
> 
> hum, and this ^^^ breaks perf_data_size(rb) ;)
> 
> static inline unsigned long perf_data_size(struct ring_buffer *rb)
> {
>         return rb->nr_pages << (PAGE_SHIFT + page_order(rb));
> }

How so? 0 << n keeps being 0, right?

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