[PATCH bpf] samples/bpf: Fix xdpsock with '-M' parameter missing unload process

[PATCH bpf] samples/bpf: Fix xdpsock with '-M' parameter missing unload process

[Wang Hai]

Execute the following command and exit, then execute it again, the
following error will be reported.

$ sudo ./samples/bpf/xdpsock -i ens4f2 -M
^C
$ sudo ./samples/bpf/xdpsock -i ens4f2 -M
libbpf: elf: skipping unrecognized data section(16) .eh_frame
libbpf: elf: skipping relo section(17) .rel.eh_frame for section(16) .eh_frame
libbpf: Kernel error message: XDP program already attached
ERROR: link set xdp fd failed

commit c9d27c9e8dc7 ("samples: bpf: Do not unload prog within xdpsock")
removed the unload prog code because of the presence of bpf_link. This
is fine if XDP_SHARED_UMEM is disable, but if it is enable, unload prog
is still needed.

Fixes: c9d27c9e8dc7 ("samples: bpf: Do not unload prog within xdpsock")
Signed-off-by: Wang Hai <wanghai38@huawei.com>
---
 samples/bpf/xdpsock_user.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
index 53e300f860bb..33d0bdebbed8 100644
--- a/samples/bpf/xdpsock_user.c
+++ b/samples/bpf/xdpsock_user.c
@@ -96,6 +96,7 @@ static int opt_xsk_frame_size = XSK_UMEM__DEFAULT_FRAME_SIZE;
 static int opt_timeout = 1000;
 static bool opt_need_wakeup = true;
 static u32 opt_num_xsks = 1;
+static u32 prog_id;
 static bool opt_busy_poll;
 static bool opt_reduced_cap;
 
@@ -461,6 +462,23 @@ static void *poller(void *arg)
 	return NULL;
 }
 
+static void remove_xdp_program(void)
+{
+	u32 curr_prog_id = 0;
+
+	if (bpf_get_link_xdp_id(opt_ifindex, &curr_prog_id, opt_xdp_flags)) {
+		printf("bpf_get_link_xdp_id failed\n");
+		exit(EXIT_FAILURE);
+	}
+
+	if (prog_id == curr_prog_id)
+		bpf_set_link_xdp_fd(opt_ifindex, -1, opt_xdp_flags);
+	else if (!curr_prog_id)
+		printf("couldn't find a prog id on a given interface\n");
+	else
+		printf("program on interface changed, not removing\n");
+}
+
 static void int_exit(int sig)
 {
 	benchmark_done = true;
@@ -471,6 +489,9 @@ static void __exit_with_error(int error, const char *file, const char *func,
 {
 	fprintf(stderr, "%s:%s:%i: errno: %d/\"%s\"\n", file, func,
 		line, error, strerror(error));
+
+	if (opt_num_xsks > 1)
+		remove_xdp_program();
 	exit(EXIT_FAILURE);
 }
 
@@ -490,6 +511,9 @@ static void xdpsock_cleanup(void)
 		if (write(sock, &cmd, sizeof(int)) < 0)
 			exit_with_error(errno);
 	}
+
+	if (opt_num_xsks > 1)
+		remove_xdp_program();
 }
 
 static void swap_mac_addresses(void *data)
@@ -857,6 +881,10 @@ static struct xsk_socket_info *xsk_configure_socket(struct xsk_umem_info *umem,
 	if (ret)
 		exit_with_error(-ret);
 
+	ret = bpf_get_link_xdp_id(opt_ifindex, &prog_id, opt_xdp_flags);
+	if (ret)
+		exit_with_error(-ret);
+
 	xsk->app_stats.rx_empty_polls = 0;
 	xsk->app_stats.fill_fail_polls = 0;
 	xsk->app_stats.copy_tx_sendtos = 0;
-- 
2.17.1

Re: [PATCH bpf] samples/bpf: Fix xdpsock with '-M' parameter missing unload process

[Magnus Karlsson]

On Mon, Jun 28, 2021 at 11:20 AM Wang Hai <wanghai38@huawei.com> wrote:
>
> Execute the following command and exit, then execute it again, the
> following error will be reported.
>
> $ sudo ./samples/bpf/xdpsock -i ens4f2 -M
> ^C
> $ sudo ./samples/bpf/xdpsock -i ens4f2 -M
> libbpf: elf: skipping unrecognized data section(16) .eh_frame
> libbpf: elf: skipping relo section(17) .rel.eh_frame for section(16) .eh_frame
> libbpf: Kernel error message: XDP program already attached
> ERROR: link set xdp fd failed
>
> commit c9d27c9e8dc7 ("samples: bpf: Do not unload prog within xdpsock")
> removed the unload prog code because of the presence of bpf_link. This
> is fine if XDP_SHARED_UMEM is disable, but if it is enable, unload prog
> is still needed.

Thank you Wang.

Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>

> Fixes: c9d27c9e8dc7 ("samples: bpf: Do not unload prog within xdpsock")
> Signed-off-by: Wang Hai <wanghai38@huawei.com>
> ---
>  samples/bpf/xdpsock_user.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
>
> diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
> index 53e300f860bb..33d0bdebbed8 100644
> --- a/samples/bpf/xdpsock_user.c
> +++ b/samples/bpf/xdpsock_user.c
> @@ -96,6 +96,7 @@ static int opt_xsk_frame_size = XSK_UMEM__DEFAULT_FRAME_SIZE;
>  static int opt_timeout = 1000;
>  static bool opt_need_wakeup = true;
>  static u32 opt_num_xsks = 1;
> +static u32 prog_id;
>  static bool opt_busy_poll;
>  static bool opt_reduced_cap;
>
> @@ -461,6 +462,23 @@ static void *poller(void *arg)
>         return NULL;
>  }
>
> +static void remove_xdp_program(void)
> +{
> +       u32 curr_prog_id = 0;
> +
> +       if (bpf_get_link_xdp_id(opt_ifindex, &curr_prog_id, opt_xdp_flags)) {
> +               printf("bpf_get_link_xdp_id failed\n");
> +               exit(EXIT_FAILURE);
> +       }
> +
> +       if (prog_id == curr_prog_id)
> +               bpf_set_link_xdp_fd(opt_ifindex, -1, opt_xdp_flags);
> +       else if (!curr_prog_id)
> +               printf("couldn't find a prog id on a given interface\n");
> +       else
> +               printf("program on interface changed, not removing\n");
> +}
> +
>  static void int_exit(int sig)
>  {
>         benchmark_done = true;
> @@ -471,6 +489,9 @@ static void __exit_with_error(int error, const char *file, const char *func,
>  {
>         fprintf(stderr, "%s:%s:%i: errno: %d/\"%s\"\n", file, func,
>                 line, error, strerror(error));
> +
> +       if (opt_num_xsks > 1)
> +               remove_xdp_program();
>         exit(EXIT_FAILURE);
>  }
>
> @@ -490,6 +511,9 @@ static void xdpsock_cleanup(void)
>                 if (write(sock, &cmd, sizeof(int)) < 0)
>                         exit_with_error(errno);
>         }
> +
> +       if (opt_num_xsks > 1)
> +               remove_xdp_program();
>  }
>
>  static void swap_mac_addresses(void *data)
> @@ -857,6 +881,10 @@ static struct xsk_socket_info *xsk_configure_socket(struct xsk_umem_info *umem,
>         if (ret)
>                 exit_with_error(-ret);
>
> +       ret = bpf_get_link_xdp_id(opt_ifindex, &prog_id, opt_xdp_flags);
> +       if (ret)
> +               exit_with_error(-ret);
> +
>         xsk->app_stats.rx_empty_polls = 0;
>         xsk->app_stats.fill_fail_polls = 0;
>         xsk->app_stats.copy_tx_sendtos = 0;
> --
> 2.17.1
>

Re: [PATCH bpf] samples/bpf: Fix xdpsock with '-M' parameter missing unload process

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf.git (refs/heads/master):

On Mon, 28 Jun 2021 17:18:15 +0800 you wrote:
> Execute the following command and exit, then execute it again, the
> following error will be reported.
> 
> $ sudo ./samples/bpf/xdpsock -i ens4f2 -M
> ^C
> $ sudo ./samples/bpf/xdpsock -i ens4f2 -M
> libbpf: elf: skipping unrecognized data section(16) .eh_frame
> libbpf: elf: skipping relo section(17) .rel.eh_frame for section(16) .eh_frame
> libbpf: Kernel error message: XDP program already attached
> ERROR: link set xdp fd failed
> 
> [...]

Here is the summary with links:
  - [bpf] samples/bpf: Fix xdpsock with '-M' parameter missing unload process
    https://git.kernel.org/bpf/bpf/c/2620e92ae6ed

You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html