netdev - [PATCH bpf-next 02/15] selftests/xsk: do not close unused file descriptors

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Date:   Tue,  6 Dec 2022 10:08:13 +0100
From:   Magnus Karlsson <magnus.karlsson@...il.com>
To:     magnus.karlsson@...el.com, bjorn@...nel.org, ast@...nel.org,
        daniel@...earbox.net, netdev@...r.kernel.org,
        maciej.fijalkowski@...el.com, bpf@...r.kernel.org, yhs@...com,
        andrii@...nel.org, martin.lau@...ux.dev, song@...nel.org,
        john.fastabend@...il.com, kpsingh@...nel.org, sdf@...gle.com,
        haoluo@...gle.com, jolsa@...nel.org
Cc:     jonathan.lemon@...il.com
Subject: [PATCH bpf-next 02/15] selftests/xsk: do not close unused file descriptors

From: Magnus Karlsson <magnus.karlsson@...el.com>

Do not close descriptors that have never been used. File descriptor
fields that are not in use are erroneously marked with the number 0,
which is a valid fd. Mark unused fds with -1 instead and do not close
these when deleting the socket.

Signed-off-by: Magnus Karlsson <magnus.karlsson@...el.com>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
---
 tools/testing/selftests/bpf/xsk.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/xsk.c b/tools/testing/selftests/bpf/xsk.c
index 39d349509ba4..5e4a6552ed37 100644
--- a/tools/testing/selftests/bpf/xsk.c
+++ b/tools/testing/selftests/bpf/xsk.c
@@ -35,6 +35,8 @@
 #include "xsk.h"
 #include "bpf_util.h"
 
+#define FD_NOT_USED (-1)
+
 #ifndef SOL_XDP
  #define SOL_XDP 283
 #endif
@@ -583,6 +585,9 @@ static void xsk_delete_bpf_maps(struct xsk_socket *xsk)
 {
 	struct xsk_ctx *ctx = xsk->ctx;
 
+	if (ctx->xsks_map_fd == FD_NOT_USED)
+		return;
+
 	bpf_map_delete_elem(ctx->xsks_map_fd, &ctx->queue_id);
 	close(ctx->xsks_map_fd);
 }
@@ -941,6 +946,9 @@ static struct xsk_ctx *xsk_create_ctx(struct xsk_socket *xsk,
 	ctx->umem = umem;
 	ctx->queue_id = queue_id;
 	bpf_strlcpy(ctx->ifname, ifname, IFNAMSIZ);
+	ctx->prog_fd = FD_NOT_USED;
+	ctx->link_fd = FD_NOT_USED;
+	ctx->xsks_map_fd = FD_NOT_USED;
 
 	ctx->fill = fill;
 	ctx->comp = comp;
@@ -1221,8 +1229,9 @@ void xsk_socket__delete(struct xsk_socket *xsk)
 
 	if (ctx->refcount == 1) {
 		xsk_delete_bpf_maps(xsk);
-		close(ctx->prog_fd);
-		if (ctx->has_bpf_link)
+		if (ctx->prog_fd != FD_NOT_USED)
+			close(ctx->prog_fd);
+		if (ctx->has_bpf_link && ctx->link_fd != FD_NOT_USED)
 			close(ctx->link_fd);
 	}
 
-- 
2.34.1