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From:   Leo Yan <leo.yan@linaro.org>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Ian Rogers <irogers@google.com>,
        linux-perf-users@vger.kernel.org, bpf@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     Leo Yan <leo.yan@linaro.org>
Subject: [PATCH v1 2/5] perf trace: Return error if a system call doesn't exist
Date:   Mon, 21 Nov 2022 07:52:34 +0000
Message-Id: <20221121075237.127706-3-leo.yan@linaro.org>
In-Reply-To: <20221121075237.127706-1-leo.yan@linaro.org>
References: <20221121075237.127706-1-leo.yan@linaro.org>
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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: b8b1033fcaa0 ("perf trace: Mark syscall ids that are not allocated to avoid unnecessary error messages")
Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
 tools/perf/builtin-trace.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 22008a31684b..bd5513b15cde 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1796,11 +1796,11 @@ 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;
-- 
2.34.1