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author | Kan Liang <kan.liang@intel.com> | 2018-01-18 13:26:17 -0800 |
---|---|---|
committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-02-15 09:51:57 -0300 |
commit | dc6c35c679e96987dc83a003f30bc2cc33c84c00 (patch) | |
tree | a43e827f305b8aba9bfedca65fbeba16a433a75c /tools/perf | |
parent | 6888ff66c44ffa3077ed69e978902d0ff4b84ae1 (diff) | |
download | linux-dc6c35c679e96987dc83a003f30bc2cc33c84c00.tar.bz2 |
perf mmap: Recalculate size for overwrite mode
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").
When the ring buffer 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 ring buffer 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>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: 7fb4b407a124 ("perf mmap: Don't discard prev in backward mode")
Link: http://lkml.kernel.org/r/1516310792-208685-3-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf')
-rw-r--r-- | tools/perf/util/mmap.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c index 05076e683938..97cf4fab564b 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); |