[RFC PATCH 3/4] bpf tools: Save the perf event fds from "maps" sections to 'struct bpf_object'

[Kaixu Xia]

This patch saves the perf_event fds from "maps" sections to struct
bpf_object. So we can enable/disable these perf events at the
appropriate time.

Signed-off-by: Kaixu Xia <xiaka...@huawei.com>
---
 tools/lib/bpf/libbpf.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 83d79c4..2b3940e 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -126,6 +126,8 @@ struct bpf_object {
         */
        size_t nr_map_fds;
        bool loaded;
+       int *bpf_event_fds;
+       int nr_bpf_event_fds;
 
        /*
         * Information when doing elf related work. Only valid if fd
@@ -629,7 +631,26 @@ bpf_program__collect_reloc(struct bpf_program *prog,
 }
 
 static int
-bpf_object__collect_perf_event_maps(void *data, int **pfd)
+bpf_object__save_event_bpf_fd(struct bpf_object *obj, int event_fd)
+{
+       void *bpf_event = obj->bpf_event_fds;
+       int nr_bpf_event = obj->nr_bpf_event_fds;
+
+       bpf_event = realloc(bpf_event, sizeof(int)*(nr_bpf_event + 1));
+
+       if (!bpf_event) {
+               pr_warning("realloc failed\n");
+               return -ENOMEM;
+       }
+
+       obj->bpf_event_fds = bpf_event;
+       obj->nr_bpf_event_fds = nr_bpf_event + 1;
+       obj->bpf_event_fds[nr_bpf_event] = event_fd;
+       return 0;
+}
+
+static int
+bpf_object__collect_perf_event_maps(struct bpf_object *obj, void *data, int 
**pfd)
 {
        int i, event_fd;
        int maps_fd = **pfd;
@@ -655,6 +676,8 @@ bpf_object__collect_perf_event_maps(void *data, int **pfd)
                        return -EINVAL;
                }
                bpf_update_elem(maps_fd, &i, &event_fd, BPF_ANY);
+               if (bpf_object__save_event_bpf_fd(obj, event_fd))
+                       return -ENOMEM;
        }
        return 0;
 }
@@ -705,7 +728,7 @@ bpf_object__create_maps(struct bpf_object *obj)
                if (def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY) {
                        void *data = obj->maps_buf + i * sizeof(struct 
bpf_map_def);
 
-                       err = bpf_object__collect_perf_event_maps(data, &pfd);
+                       err = bpf_object__collect_perf_event_maps(obj, data, 
&pfd);
                        if (err < 0) {
                                pr_warning("failed to collect perf_event maps: 
%s\n",
                                            strerror(errno));
@@ -1074,6 +1097,7 @@ void bpf_object__close(struct bpf_object *obj)
                        bpf_program__exit(&obj->programs[i]);
        }
        zfree(&obj->programs);
+       zfree(&obj->bpf_event_fds);
 
        list_del(&obj->list);
        free(obj);
-- 
1.8.3.4

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