netdev - [PATCH] tools: perf: add missing unlock to maps_

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Date:   Mon, 20 Jan 2020 17:15:54 +0300
From:   Cengiz Can <cengiz@...nel.wtf>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
        netdev@...r.kernel.org, Cengiz Can <cengiz@...nel.wtf>
Subject: [PATCH] tools: perf: add missing unlock to maps__insert error case

`tools/perf/util/map.c` has a function named `maps__insert` that
acquires a write lock if its in multithread context.

Even though this lock is released when function successfully completes,
there's a branch that is executed when `maps_by_name == NULL` that
returns from this function without releasing the write lock.

Added an `up_write` to release the lock when this happens.

Signed-off-by: Cengiz Can <cengiz@...nel.wtf>
---

Hello Arnaldo,

I'm not exactly sure about the order that we must call up_write here.

Please tell me if the `__maps__free_maps_by_name` frees the
`rw_semaphore`. If that's the case, should we change the order to unlock and free?

Thanks!

 tools/perf/util/map.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index fdd5bddb3075..f67960bedebb 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -549,6 +549,7 @@ void maps__insert(struct maps *maps, struct map *map)

 			if (maps_by_name == NULL) {
 				__maps__free_maps_by_name(maps);
+				up_write(&maps->lock);
 				return;
 			}

--
2.25.0