perf trace: Return error if a system call doesn't exist

[ Upstream commit d4223e1776c30b2ce8d0e6eaadcbf696e60fca3c ]

When a system call is not detected, the reason is either because the
system call ID is out of scope or failure to find the corresponding path
in the sysfs, trace__read_syscall_info() returns zero.  Finally, without
returning an error value it introduces confusion for the caller.

This patch lets the function trace__read_syscall_info() to return
-EEXIST when a system call doesn't exist.

Fixes: b8b1033fcaa091d8 ("perf trace: Mark syscall ids that are not allocated to avoid unnecessary error messages")
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: bpf@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221121075237.127706-3-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 2bf2119..aaa465d 100644 (file)
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1782,11 +1782,11 @@ static int trace__read_syscall_info(struct trace *trace, int id)
 #endif
        sc = trace->syscalls.table + id;
        if (sc->nonexistent)
-               return 0;
+               return -EEXIST;
 
        if (name == NULL) {
                sc->nonexistent = true;
-               return 0;
+               return -EEXIST;
        }
 
        sc->name = name;