6.15-stable review patch. If anyone has any objections, please let me know.
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From: Anubhav Shelat ashelat@redhat.com
[ Upstream commit c7a48ea9b919e2fa0e4a1d9938fdb03e9afe276c ]
The syscalls that were consistently observed were set_robust_list and rseq. This is because perf cannot find their child process.
This change ensures that the return value is always printed.
Before: 0.256 ( 0.001 ms): set_robust_list(head: 0x7f09c77dba20, len: 24) = 0.259 ( 0.001 ms): rseq(rseq: 0x7f09c77dc0e0, rseq_len: 32, sig: 1392848979) = After: 0.270 ( 0.002 ms): set_robust_list(head: 0x7f0bb14a6a20, len: 24) = 0 0.273 ( 0.002 ms): rseq(rseq: 0x7f0bb14a70e0, rseq_len: 32, sig: 1392848979) = 0
Committer notes:
As discussed in the thread in the Link: tag below, these two don't return a pid, but for syscalls returning one, we need to print the result and if we manage to find the children in 'perf trace' data structures, then print its name as well.
Fixes: 11c8e39f5133aed9 ("perf trace: Infrastructure to show COMM strings for syscalls returning PIDs") Reviewed-by: Howard Chu howardchu95@gmail.com Signed-off-by: Anubhav Shelat ashelat@redhat.com Acked-by: Namhyung Kim namhyung@kernel.org Cc: Adrian Hunter adrian.hunter@intel.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Dapeng Mi dapeng1.mi@linux.intel.com Cc: Ian Rogers irogers@google.com Cc: Ingo Molnar mingo@redhat.com Cc: James Clark james.clark@linaro.org Cc: Jiri Olsa jolsa@kernel.org Cc: Kan Liang kan.liang@linux.intel.com Cc: Mark Rutland mark.rutland@arm.com Cc: Michael Petlan mpetlan@redhat.com Cc: Peter Zijlstra peterz@infradead.org Link: https://lore.kernel.org/r/20250403160411.159238-2-ashelat@redhat.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/builtin-trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index f98b5efb1f96c..7304e62b69fee 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -3005,8 +3005,8 @@ errno_print: { else if (sc->fmt->errpid) { struct thread *child = machine__find_thread(trace->host, ret, ret);
+ fprintf(trace->output, "%ld", ret); if (child != NULL) { - fprintf(trace->output, "%ld", ret); if (thread__comm_set(child)) fprintf(trace->output, " (%s)", thread__comm_str(child)); thread__put(child);