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Message-ID: <578B66F6-E746-413F-B0B4-8BDB6B320FE3@flugsvamp.com> Date: Fri, 01 Mar 2019 09:17:40 -0800 From: "Jonathan Lemon" <jlemon@...gsvamp.com> To: "Yonghong Song" <yhs@...com> Cc: netdev@...r.kernel.org, "Alexei Starovoitov" <ast@...com>, "Daniel Borkmann" <daniel@...earbox.net>, kernel-team@...com Subject: Re: [PATCH bpf-next] samples/bpf: silence compiler warning for xdpsock_user.c On 28 Feb 2019, at 22:19, Yonghong Song wrote: > Compiling xdpsock_user.c with 4.8.5, I hit the following > compilation warning: > HOSTCC samples/bpf/xdpsock_user.o > /data/users/yhs/work/net-next/samples/bpf/xdpsock_user.c: In > function ‘main’: > /data/users/yhs/work/net-next/samples/bpf/xdpsock_user.c:449:6: > warning: ‘idx_cq’ may be used unini > tialized in this function [-Wmaybe-uninitialized] > u32 idx_cq, idx_fq; > ^ > /data/users/yhs/work/net-next/samples/bpf/xdpsock_user.c:606:7: > warning: ‘idx_rx’ may be used unini > tialized in this function [-Wmaybe-uninitialized] > u32 idx_rx, idx_tx = 0; > ^ > /data/users/yhs/work/net-next/samples/bpf/xdpsock_user.c:506:6: > warning: ‘idx_rx’ may be used unini > tialized in this function [-Wmaybe-uninitialized] > u32 idx_rx, idx_fq = 0; > > As an example, the code pattern looks like: > u32 idx_cq; > ... > ret = xsk_ring_prod__reserve(&xsk->umem->fq, rcvd, &idx_fq); > if (ret) { > ... > } > ... idx_fq ... > The compiler warns since it does not know whether &idx_fq is assigned > or not inside the library function xsk_ring_prod__reserve(). > > Let us assign an initial value 0 to such auto variables to silence > compiler warning. > > Fixes: 248c7f9c0e21 ("samples/bpf: convert xdpsock to use libbpf for > AF_XDP access") > Signed-off-by: Yonghong Song <yhs@...com> > --- > samples/bpf/xdpsock_user.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c > index 9c76d6d43deb..d08ee1ab7bb4 100644 > --- a/samples/bpf/xdpsock_user.c > +++ b/samples/bpf/xdpsock_user.c > @@ -446,7 +446,7 @@ static void kick_tx(struct xsk_socket_info *xsk) > > static inline void complete_tx_l2fwd(struct xsk_socket_info *xsk) > { > - u32 idx_cq, idx_fq; > + u32 idx_cq = 0, idx_fq = 0; > unsigned int rcvd; > size_t ndescs; > > @@ -503,7 +503,7 @@ static inline void complete_tx_only(struct > xsk_socket_info *xsk) > static void rx_drop(struct xsk_socket_info *xsk) > { > unsigned int rcvd, i; > - u32 idx_rx, idx_fq = 0; > + u32 idx_rx = 0, idx_fq = 0; > int ret; > > rcvd = xsk_ring_cons__peek(&xsk->rx, BATCH_SIZE, &idx_rx); > @@ -603,7 +603,7 @@ static void l2fwd(struct xsk_socket_info *xsk) > { > for (;;) { > unsigned int rcvd, i; > - u32 idx_rx, idx_tx = 0; > + u32 idx_rx = 0, idx_tx = 0; > int ret; > > for (;;) { > -- > 2.17.1 Acked-by: Jonathan Lemon <jonathan.lemon@...il.com>
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