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Date: Thu, 21 Apr 2022 00:39:57 +0000 From: Alexander Lobakin <alobakin@...me> To: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org> Cc: Alexander Lobakin <alobakin@...me>, Maciej Fijalkowski <maciej.fijalkowski@...el.com>, Song Liu <songliubraving@...com>, Kumar Kartikeya Dwivedi <memxor@...il.com>, bpf@...r.kernel.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: [PATCH v2 bpf 11/11] samples/bpf: xdpsock: fix -Wmaybe-uninitialized Fix two sort-of-false-positives in the xdpsock userspace part: samples/bpf/xdpsock_user.c: In function 'main': samples/bpf/xdpsock_user.c:1531:47: warning: 'tv_usec' may be used uninitialized in this function [-Wmaybe-uninitialized] 1531 | pktgen_hdr->tv_usec = htonl(tv_usec); | ^~~~~~~~~~~~~~ samples/bpf/xdpsock_user.c:1500:26: note: 'tv_usec' was declared here 1500 | u32 idx, tv_sec, tv_usec; | ^~~~~~~ samples/bpf/xdpsock_user.c:1530:46: warning: 'tv_sec' may be used uninitialized in this function [-Wmaybe-uninitialized] 1530 | pktgen_hdr->tv_sec = htonl(tv_sec); | ^~~~~~~~~~~~~ samples/bpf/xdpsock_user.c:1500:18: note: 'tv_sec' was declared here 1500 | u32 idx, tv_sec, tv_usec; | ^~~~~~ Both variables are always initialized when @opt_tstamp == true and they're being used also only when @opt_tstamp == true. However, that variable comes from the BSS and is being toggled from another function. They can't be executed simultaneously to actually trigger undefined behaviour, but purely technically it is a correct warning. Just initialize them with zeroes. Fixes: eb68db45b747 ("samples/bpf: xdpsock: Add timestamp for Tx-only operation") Acked-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com> Acked-by: Song Liu <songliubraving@...com> Signed-off-by: Alexander Lobakin <alobakin@...me> --- samples/bpf/xdpsock_user.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c index 9747d47a0a8f..a6d8291c8b38 100644 --- a/samples/bpf/xdpsock_user.c +++ b/samples/bpf/xdpsock_user.c @@ -1497,7 +1497,7 @@ static void rx_drop_all(void) static int tx_only(struct xsk_socket_info *xsk, u32 *frame_nb, int batch_size, unsigned long tx_ns) { - u32 idx, tv_sec, tv_usec; + u32 idx, tv_sec = 0, tv_usec = 0; unsigned int i; while (xsk_ring_prod__reserve(&xsk->tx, batch_size, &idx) < -- 2.36.0
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