linux-kernel - [PATCH AUTOSEL 5.4 168/175] libbpf: Fix perf_buffer_

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Date:   Mon,  8 Jun 2020 19:18:41 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Eelco Chaudron <echaudro@...hat.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andriin@...com>,
        Alexei Starovoitov <ast@...nel.org>,
        Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 168/175] libbpf: Fix perf_buffer__free() API for sparse allocs

From: Eelco Chaudron <echaudro@...hat.com>

[ Upstream commit 601b05ca6edb0422bf6ce313fbfd55ec7bbbc0fd ]

In case the cpu_bufs are sparsely allocated they are not all
free'ed. These changes will fix this.

Fixes: fb84b8224655 ("libbpf: add perf buffer API")
Signed-off-by: Eelco Chaudron <echaudro@...hat.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Acked-by: Andrii Nakryiko <andriin@...com>
Link: https://lore.kernel.org/bpf/159056888305.330763.9684536967379110349.stgit@ebuild
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/lib/bpf/libbpf.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 281cc65276e0..2a1dbf52fc9a 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -5358,9 +5358,12 @@ void perf_buffer__free(struct perf_buffer *pb)
 	if (!pb)
 		return;
 	if (pb->cpu_bufs) {
-		for (i = 0; i < pb->cpu_cnt && pb->cpu_bufs[i]; i++) {
+		for (i = 0; i < pb->cpu_cnt; i++) {
 			struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
 
+			if (!cpu_buf)
+				continue;
+
 			bpf_map_delete_elem(pb->map_fd, &cpu_buf->map_key);
 			perf_buffer__free_cpu_buf(pb, cpu_buf);
 		}
-- 
2.25.1