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-rw-r--r--tools/lib/bpf/libbpf.c40
-rw-r--r--tools/lib/bpf/libbpf.h1
-rw-r--r--tools/lib/bpf/libbpf.map1
3 files changed, 32 insertions, 10 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 906bbbf7b2e4..2a341a5b9f63 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -6245,17 +6245,37 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
}
struct bpf_link {
+ int (*detach)(struct bpf_link *link);
int (*destroy)(struct bpf_link *link);
+ bool disconnected;
};
+/* Release "ownership" of underlying BPF resource (typically, BPF program
+ * attached to some BPF hook, e.g., tracepoint, kprobe, etc). Disconnected
+ * link, when destructed through bpf_link__destroy() call won't attempt to
+ * detach/unregisted that BPF resource. This is useful in situations where,
+ * say, attached BPF program has to outlive userspace program that attached it
+ * in the system. Depending on type of BPF program, though, there might be
+ * additional steps (like pinning BPF program in BPF FS) necessary to ensure
+ * exit of userspace program doesn't trigger automatic detachment and clean up
+ * inside the kernel.
+ */
+void bpf_link__disconnect(struct bpf_link *link)
+{
+ link->disconnected = true;
+}
+
int bpf_link__destroy(struct bpf_link *link)
{
- int err;
+ int err = 0;
if (!link)
return 0;
- err = link->destroy(link);
+ if (!link->disconnected && link->detach)
+ err = link->detach(link);
+ if (link->destroy)
+ link->destroy(link);
free(link);
return err;
@@ -6266,7 +6286,7 @@ struct bpf_link_fd {
int fd; /* hook FD */
};
-static int bpf_link__destroy_perf_event(struct bpf_link *link)
+static int bpf_link__detach_perf_event(struct bpf_link *link)
{
struct bpf_link_fd *l = (void *)link;
int err;
@@ -6298,10 +6318,10 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog,
return ERR_PTR(-EINVAL);
}
- link = malloc(sizeof(*link));
+ link = calloc(1, sizeof(*link));
if (!link)
return ERR_PTR(-ENOMEM);
- link->link.destroy = &bpf_link__destroy_perf_event;
+ link->link.detach = &bpf_link__detach_perf_event;
link->fd = pfd;
if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
@@ -6608,7 +6628,7 @@ out:
return link;
}
-static int bpf_link__destroy_fd(struct bpf_link *link)
+static int bpf_link__detach_fd(struct bpf_link *link)
{
struct bpf_link_fd *l = (void *)link;
@@ -6629,10 +6649,10 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
return ERR_PTR(-EINVAL);
}
- link = malloc(sizeof(*link));
+ link = calloc(1, sizeof(*link));
if (!link)
return ERR_PTR(-ENOMEM);
- link->link.destroy = &bpf_link__destroy_fd;
+ link->link.detach = &bpf_link__detach_fd;
pfd = bpf_raw_tracepoint_open(tp_name, prog_fd);
if (pfd < 0) {
@@ -6668,10 +6688,10 @@ struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog)
return ERR_PTR(-EINVAL);
}
- link = malloc(sizeof(*link));
+ link = calloc(1, sizeof(*link));
if (!link)
return ERR_PTR(-ENOMEM);
- link->link.destroy = &bpf_link__destroy_fd;
+ link->link.detach = &bpf_link__detach_fd;
pfd = bpf_raw_tracepoint_open(NULL, prog_fd);
if (pfd < 0) {
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index f7084235bae9..ad8c1c127933 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -215,6 +215,7 @@ LIBBPF_API void bpf_program__unload(struct bpf_program *prog);
struct bpf_link;
+LIBBPF_API void bpf_link__disconnect(struct bpf_link *link);
LIBBPF_API int bpf_link__destroy(struct bpf_link *link);
LIBBPF_API struct bpf_link *
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 1376d992a703..e3a471f38a71 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -212,6 +212,7 @@ LIBBPF_0.0.6 {
LIBBPF_0.0.7 {
global:
btf_dump__emit_type_decl;
+ bpf_link__disconnect;
bpf_object__find_program_by_name;
bpf_object__attach_skeleton;
bpf_object__destroy_skeleton;