On 2019-06-03 15:19, Maciej Fijalkowski wrote:
Since xsk support in libbpf loads the xdp program interface, make it
also responsible for its removal. Store the prog id in xsk_socket_config
so when removing the program we are still able to compare the current
program id with the id from the attachment time and make a decision
onward.
While at it, remove the socket/umem in xdpsock's error path.
We're loading a new, or reusing an existing XDP program at socket
creation, but tearing it down at *socket delete* is explicitly left to
the application.
For a per-queue XDP program (tied to the socket), this kind cleanup would
make sense.
The intention with the libbpf AF_XDP support was to leave the XDP
handling to whatever XDP orchestration process availble. It's not part
of libbpf. For convenience, *loading/lookup of the XDP program* was
added even though this was an asymmetry.
For the sample application, this makes sense, but for larger/real
applications?
OTOH I like the idea of a scoped cleanup "when all sockets are gone",
the XDP program + maps are removed.
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx>
---
samples/bpf/xdpsock_user.c | 33 ++++++++++-----------------------
tools/lib/bpf/xsk.c | 32 ++++++++++++++++++++++++++++++++
tools/lib/bpf/xsk.h | 1 +
3 files changed, 43 insertions(+), 23 deletions(-)
diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
index e9dceb09b6d1..123862b16dd4 100644
--- a/samples/bpf/xdpsock_user.c
+++ b/samples/bpf/xdpsock_user.c
@@ -68,7 +68,6 @@ static int opt_queue;
static int opt_poll;
static int opt_interval = 1;
static u32 opt_xdp_bind_flags;
-static __u32 prog_id;
struct xsk_umem_info {
struct xsk_ring_prod fq;
@@ -170,22 +169,6 @@ 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)
{
struct xsk_umem *umem = xsks[0]->umem->umem;
@@ -195,7 +178,6 @@ static void int_exit(int sig)
dump_stats();
xsk_socket__delete(xsks[0]->xsk);
(void)xsk_umem__delete(umem);
- remove_xdp_program();
exit(EXIT_SUCCESS);
}
@@ -206,7 +188,16 @@ 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));
dump_stats();
- remove_xdp_program();
+
+ if (xsks[0]->xsk)
+ xsk_socket__delete(xsks[0]->xsk);
+
+ if (xsks[0]->umem) {
+ struct xsk_umem *umem = xsks[0]->umem->umem;
+
+ (void)xsk_umem__delete(umem);
+ }
+
exit(EXIT_FAILURE);
}
@@ -312,10 +303,6 @@ 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);
-
return xsk;
}
diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index 514ab3fb06f4..e28bedb0b078 100644
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -259,6 +259,8 @@ int xsk_umem__create(struct xsk_umem **umem_ptr, void *umem_area, __u64 size,
static int xsk_load_xdp_prog(struct xsk_socket *xsk)
{
static const int log_buf_size = 16 * 1024;
+ struct bpf_prog_info info = {};
+ __u32 info_len = sizeof(info);
char log_buf[log_buf_size];
int err, prog_fd;
@@ -321,6 +323,14 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
return err;
}
+ err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+ if (err) {
+ pr_warning("can't get prog info - %s\n", strerror(errno));
+ close(prog_fd);
+ return err;
+ }
+ xsk->config.prog_id = info.id;
+
xsk->prog_fd = prog_fd;
return 0;
}
@@ -483,6 +493,25 @@ static int xsk_set_bpf_maps(struct xsk_socket *xsk)
return err;
}
+static void xsk_remove_xdp_prog(struct xsk_socket *xsk)
+{
+ __u32 prog_id = xsk->config.prog_id;
+ __u32 curr_prog_id = 0;
+ int err;
+
+ err = bpf_get_link_xdp_id(xsk->ifindex, &curr_prog_id,
+ xsk->config.xdp_flags);
+ if (err)
+ return;
+
+ if (prog_id == curr_prog_id)
+ bpf_set_link_xdp_fd(xsk->ifindex, -1, xsk->config.xdp_flags);
+ else if (!curr_prog_id)
+ pr_warning("couldn't find a prog id on a given interface\n");
+ else
+ pr_warning("program on interface changed, not removing\n");
+}
+
static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
{
__u32 prog_id = 0;
@@ -506,6 +535,7 @@ static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
err = xsk_lookup_bpf_maps(xsk);
if (err)
goto out_load;
+ xsk->config.prog_id = prog_id;
}
err = xsk_set_bpf_maps(xsk);
@@ -744,6 +774,8 @@ void xsk_socket__delete(struct xsk_socket *xsk)
}
+ xsk_remove_xdp_prog(xsk);
+
xsk->umem->refcount--;
/* Do not close an fd that also has an associated umem connected
* to it.
diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h
index 82ea71a0f3ec..e1b23e9432c9 100644
--- a/tools/lib/bpf/xsk.h
+++ b/tools/lib/bpf/xsk.h
@@ -186,6 +186,7 @@ struct xsk_socket_config {
__u32 tx_size;
__u32 libbpf_flags;
__u32 xdp_flags;
+ __u32 prog_id;
__u16 bind_flags;
};
