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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jeremy Cline <jcline@redhat.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andriin@fb.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 53/83] libbpf: Initialize *nl_pid so gcc 10 is happy
Date:   Fri,  1 May 2020 15:23:32 +0200
Message-Id: <20200501131538.906016002@linuxfoundation.org>
In-Reply-To: <20200501131524.004332640@linuxfoundation.org>
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From: Jeremy Cline <jcline@redhat.com>

[ Upstream commit 4734b0fefbbf98f8c119eb8344efa19dac82cd2c ]

Builds of Fedora's kernel-tools package started to fail with "may be
used uninitialized" warnings for nl_pid in bpf_set_link_xdp_fd() and
bpf_get_link_xdp_info() on the s390 architecture.

Although libbpf_netlink_open() always returns a negative number when it
does not set *nl_pid, the compiler does not determine this and thus
believes the variable might be used uninitialized. Assuage gcc's fears
by explicitly initializing nl_pid.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1807781

Signed-off-by: Jeremy Cline <jcline@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200404051430.698058-1-jcline@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/lib/bpf/netlink.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/netlink.c b/tools/lib/bpf/netlink.c
index ce3ec81b71c01..88416be2bf994 100644
--- a/tools/lib/bpf/netlink.c
+++ b/tools/lib/bpf/netlink.c
@@ -137,7 +137,7 @@ int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)
 		struct ifinfomsg ifinfo;
 		char             attrbuf[64];
 	} req;
-	__u32 nl_pid;
+	__u32 nl_pid = 0;
 
 	sock = libbpf_netlink_open(&nl_pid);
 	if (sock < 0)
@@ -254,7 +254,7 @@ int bpf_get_link_xdp_id(int ifindex, __u32 *prog_id, __u32 flags)
 {
 	struct xdp_id_md xdp_id = {};
 	int sock, ret;
-	__u32 nl_pid;
+	__u32 nl_pid = 0;
 	__u32 mask;
 
 	if (flags & ~XDP_FLAGS_MASK)
-- 
2.20.1