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From: Cengiz Can <cengiz@kernel.wtf>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
	netdev@vger.kernel.org, Cengiz Can <cengiz@kernel.wtf>
Subject: [PATCH] tools: perf: add missing unlock to maps__insert error case
Date: Mon, 20 Jan 2020 17:15:54 +0300
Message-ID: <20200120141553.23934-1-cengiz@kernel.wtf> (raw)

`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@kernel.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


             reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-20 14:15 Cengiz Can [this message]
2020-01-31  8:38 ` Arnaldo Carvalho de Melo
2020-01-31  8:43   ` Arnaldo Carvalho de Melo
2020-01-31 15:42     ` Cengiz Can
2020-02-05 15:45 ` [tip: perf/urgent] perf maps: Add missing unlock to maps__insert() " tip-bot2 for Cengiz Can

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