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| author | Hongfu Li <lihongfu@kylinos.cn> | 2026-07-13 17:36:26 +0800 |
|---|---|---|
| committer | Namhyung Kim <namhyung@kernel.org> | 2026-07-15 11:16:41 -0700 |
| commit | d30f2d869b6a2e985351867424037eb7bcb57386 (patch) | |
| tree | afb93c4bbc4788fa42f8eb1d3db5ed244022873e | |
| parent | ea46211d7e9a2210b62c40e56b2d6540c0b4b083 (diff) | |
| download | linux-d30f2d869b6a2e985351867424037eb7bcb57386.tar.gz linux-d30f2d869b6a2e985351867424037eb7bcb57386.zip | |
perf doc: Fix mmap failure checks in topdown example
Use MAP_FAILED instead of NULL to detect mmap errors, and fix the
slots_p variable name typo in the sample code.
Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
| -rw-r--r-- | tools/perf/Documentation/topdown.txt | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/tools/perf/Documentation/topdown.txt b/tools/perf/Documentation/topdown.txt index 5c17fff694ee..fd4214f9a7b0 100644 --- a/tools/perf/Documentation/topdown.txt +++ b/tools/perf/Documentation/topdown.txt @@ -87,7 +87,7 @@ if (slots_fd < 0) /* Memory mapping the fd permits _rdpmc calls from userspace */ void *slots_p = mmap(0, getpagesize(), PROT_READ, MAP_SHARED, slots_fd, 0); -if (!slot_p) +if (slots_p == MAP_FAILED) .... error ... /* @@ -107,7 +107,7 @@ if (metrics_fd < 0) /* Memory mapping the fd permits _rdpmc calls from userspace */ void *metrics_p = mmap(0, getpagesize(), PROT_READ, MAP_SHARED, metrics_fd, 0); -if (!metrics_p) +if (metrics_p == MAP_FAILED) ... error ... Note: the file descriptors returned by the perf_event_open calls must be memory |