5f1c4225f6
The perf_evlist__prepare_workload() method works by forking and then waiting on a fd that must be written to to allow the workload to be exec()ed. But if the tool calling it fails to, say, set up the events with which it wants to sample the workload for, it will not call perf_evlist__start_workload(), but even in this case the workload ended up running: [acme@zoo linux]$ trace /bin/echo workload ends up running, it should not... Couldn't mmap the events: Operation not permitted workload ends up running, it should not... [acme@zoo linux]$ So check if at least one byte was written before letting exec() be called. Now the expected behaviour: [acme@zoo linux]$ trace /bin/echo workload ends up running, it should not... Couldn't mmap the events: Operation not permitted [acme@zoo linux]$ Acked-by: Jiri Olsa <jolsa@redhat.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Don Zickus <dzickus@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/n/tip-oh1ixo8m74rf295a05gfjw8b@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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