| Date | Thu, 1 Feb 2018 18:23:13 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH V5 02/17] perf mmap: fix: recalculate size for overwrite mode. |
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Em Thu, Jan 18, 2018 at 01:26:17PM -0800, kan.liang@intel.com escreveu: > From: Kan Liang <kan.liang@intel.com> > > In perf_mmap__push(), the 'size' need to be recalculated, otherwise the > invalid data might be pushed to the record in overwrite mode. > > The issue is introduced by commit 7fb4b407a124 ("perf mmap: Don't > discard prev in backward mode").
In these cases, please add the Fixes tag, like:
Fixes: 7fb4b407a124 ("perf mmap: Don't discard prev in backward mode")
I'm doing it this time.
Thanks,
- Arnaldo
> When the ringbuffer is full in overwrite mode, backward_rb_find_range > will be called to recalculate the 'start' and 'end'. The 'size' needs to > be recalculated accordingly. > > Unconditionally recalculate the 'size', not just for full ringbuffer in > overwrite mode. Because, > - There is no harmful to recalculate the 'size' for other cases. > - The code of calculating 'start' and 'end' will be factored out later. > The new function does not need to return 'size'. > > Signed-off-by: Kan Liang <kan.liang@intel.com> > --- > tools/perf/util/mmap.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c > index 05076e6..97cf4fa 100644 > --- a/tools/perf/util/mmap.c > +++ b/tools/perf/util/mmap.c > @@ -302,6 +302,8 @@ int perf_mmap__push(struct perf_mmap *md, bool overwrite, > return -1; > } > > + size = end - start; > + > if ((start & md->mask) + size != (end & md->mask)) { > buf = &data[start & md->mask]; > size = md->mask + 1 - (start & md->mask); > -- > 2.5.5
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