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Date: Sat, 1 Jun 2019 23:05:58 +0000
From: Song Liu <songliubraving@...com>
To: Jonathan Lemon <jonathan.lemon@...il.com>
CC: Networking <netdev@...r.kernel.org>,
Kernel Team <Kernel-team@...com>,
"bjorn.topel@...el.com" <bjorn.topel@...el.com>,
"magnus.karlsson@...el.com" <magnus.karlsson@...el.com>
Subject: Re: [PATCH v3 bpf-next 2/2] libbpf: remove qidconf and better support
external bpf programs.
> On May 31, 2019, at 11:57 AM, Jonathan Lemon <jonathan.lemon@...il.com> wrote:
>
> Use the recent change to XSKMAP bpf_map_lookup_elem() to test if
> there is a xsk present in the map instead of duplicating the work
> with qidconf.
>
> Fix things so callers using XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD
> bypass any internal bpf maps, so xsk_socket__{create|delete} works
> properly.
>
> Signed-off-by: Jonathan Lemon <jonathan.lemon@...il.com>
> ---
> tools/lib/bpf/xsk.c | 79 +++++++++------------------------------------
> 1 file changed, 16 insertions(+), 63 deletions(-)
>
> diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
> index 38667b62f1fe..7ce7494b5b50 100644
> --- a/tools/lib/bpf/xsk.c
> +++ b/tools/lib/bpf/xsk.c
> @@ -60,10 +60,8 @@ struct xsk_socket {
> struct xsk_umem *umem;
> struct xsk_socket_config config;
> int fd;
> - int xsks_map;
> int ifindex;
> int prog_fd;
> - int qidconf_map_fd;
> int xsks_map_fd;
> __u32 queue_id;
> char ifname[IFNAMSIZ];
> @@ -265,15 +263,11 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
> /* This is the C-program:
> * SEC("xdp_sock") int xdp_sock_prog(struct xdp_md *ctx)
> * {
> - * int *qidconf, index = ctx->rx_queue_index;
> + * int index = ctx->rx_queue_index;
> *
> * // A set entry here means that the correspnding queue_id
> * // has an active AF_XDP socket bound to it.
> - * qidconf = bpf_map_lookup_elem(&qidconf_map, &index);
> - * if (!qidconf)
> - * return XDP_ABORTED;
> - *
> - * if (*qidconf)
> + * if (bpf_map_lookup_elem(&xsks_map, &index))
> * return bpf_redirect_map(&xsks_map, index, 0);
> *
> * return XDP_PASS;
> @@ -286,15 +280,10 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
> BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_1, -4),
> BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
> BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4),
> - BPF_LD_MAP_FD(BPF_REG_1, xsk->qidconf_map_fd),
> + BPF_LD_MAP_FD(BPF_REG_1, xsk->xsks_map_fd),
> BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
> BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
> - BPF_MOV32_IMM(BPF_REG_0, 0),
> - /* if r1 == 0 goto +8 */
> - BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 8),
> BPF_MOV32_IMM(BPF_REG_0, 2),
> - /* r1 = *(u32 *)(r1 + 0) */
> - BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_1, 0),
> /* if r1 == 0 goto +5 */
> BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 5),
> /* r2 = *(u32 *)(r10 - 4) */
> @@ -366,18 +355,11 @@ static int xsk_create_bpf_maps(struct xsk_socket *xsk)
> if (max_queues < 0)
> return max_queues;
>
> - fd = bpf_create_map_name(BPF_MAP_TYPE_ARRAY, "qidconf_map",
> + fd = bpf_create_map_name(BPF_MAP_TYPE_XSKMAP, "xsks_map",
> sizeof(int), sizeof(int), max_queues, 0);
> if (fd < 0)
> return fd;
> - xsk->qidconf_map_fd = fd;
>
> - fd = bpf_create_map_name(BPF_MAP_TYPE_XSKMAP, "xsks_map",
> - sizeof(int), sizeof(int), max_queues, 0);
> - if (fd < 0) {
> - close(xsk->qidconf_map_fd);
> - return fd;
> - }
> xsk->xsks_map_fd = fd;
>
> return 0;
> @@ -385,10 +367,8 @@ static int xsk_create_bpf_maps(struct xsk_socket *xsk)
>
> static void xsk_delete_bpf_maps(struct xsk_socket *xsk)
> {
> - close(xsk->qidconf_map_fd);
> + bpf_map_delete_elem(xsk->xsks_map_fd, &xsk->queue_id);
> close(xsk->xsks_map_fd);
> - xsk->qidconf_map_fd = -1;
> - xsk->xsks_map_fd = -1;
> }
>
> static int xsk_lookup_bpf_maps(struct xsk_socket *xsk)
> @@ -417,10 +397,9 @@ static int xsk_lookup_bpf_maps(struct xsk_socket *xsk)
> if (err)
> goto out_map_ids;
>
> - for (i = 0; i < prog_info.nr_map_ids; i++) {
> - if (xsk->qidconf_map_fd != -1 && xsk->xsks_map_fd != -1)
> - break;
> + xsk->xsks_map_fd = -1;
>
> + for (i = 0; i < prog_info.nr_map_ids; i++) {
> fd = bpf_map_get_fd_by_id(map_ids[i]);
> if (fd < 0)
> continue;
> @@ -431,11 +410,6 @@ static int xsk_lookup_bpf_maps(struct xsk_socket *xsk)
> continue;
> }
>
> - if (!strcmp(map_info.name, "qidconf_map")) {
> - xsk->qidconf_map_fd = fd;
> - continue;
> - }
> -
> if (!strcmp(map_info.name, "xsks_map")) {
> xsk->xsks_map_fd = fd;
> continue;
> @@ -445,40 +419,18 @@ static int xsk_lookup_bpf_maps(struct xsk_socket *xsk)
> }
>
> err = 0;
> - if (xsk->qidconf_map_fd < 0 || xsk->xsks_map_fd < 0) {
> + if (xsk->xsks_map_fd == -1)
> err = -ENOENT;
> - xsk_delete_bpf_maps(xsk);
> - }
>
> out_map_ids:
> free(map_ids);
> return err;
> }
>
> -static void xsk_clear_bpf_maps(struct xsk_socket *xsk)
> -{
> - int qid = false;
> -
> - bpf_map_update_elem(xsk->qidconf_map_fd, &xsk->queue_id, &qid, 0);
> - bpf_map_delete_elem(xsk->xsks_map_fd, &xsk->queue_id);
> -}
> -
> static int xsk_set_bpf_maps(struct xsk_socket *xsk)
> {
> - int qid = true, fd = xsk->fd, err;
> -
> - err = bpf_map_update_elem(xsk->qidconf_map_fd, &xsk->queue_id, &qid, 0);
> - if (err)
> - goto out;
> -
> - err = bpf_map_update_elem(xsk->xsks_map_fd, &xsk->queue_id, &fd, 0);
> - if (err)
> - goto out;
> -
> - return 0;
> -out:
> - xsk_clear_bpf_maps(xsk);
> - return err;
> + return bpf_map_update_elem(xsk->xsks_map_fd, &xsk->queue_id,
> + &xsk->fd, 0);
> }
>
> static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
> @@ -514,6 +466,7 @@ static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
>
> out_load:
> close(xsk->prog_fd);
> + xsk->prog_fd = -1;
I found xsk->prog_fd confusing. Why do we need to set it here?
I think we don't need to call xsk_delete_bpf_maps() in out_load path?
> out_maps:
> xsk_delete_bpf_maps(xsk);
> return err;
> @@ -643,9 +596,7 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
> goto out_mmap_tx;
> }
>
> - xsk->qidconf_map_fd = -1;
> - xsk->xsks_map_fd = -1;
> -
> + xsk->prog_fd = -1;
> if (!(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) {
> err = xsk_setup_xdp_prog(xsk);
> if (err)
> @@ -708,8 +659,10 @@ void xsk_socket__delete(struct xsk_socket *xsk)
> if (!xsk)
> return;
>
> - xsk_clear_bpf_maps(xsk);
> - xsk_delete_bpf_maps(xsk);
> + if (xsk->prog_fd != -1) {
> + xsk_delete_bpf_maps(xsk);
> + close(xsk->prog_fd);
Here, we use prog_fd != -1 to gate xsk_delete_bpf_maps(), which is
confusing. I looked at the code for quite sometime, but still cannot
confirm it is correct.
Thanks,
Song
> + }
>
> optlen = sizeof(off);
> err = getsockopt(xsk->fd, SOL_XDP, XDP_MMAP_OFFSETS, &off, &optlen);
> --
> 2.17.1
>
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