bpf: introduce update_effective_progs()

__cgroup_bpf_attach() and __cgroup_bpf_detach() functions have
a good amount of duplicated code, which is possible to eliminate
by introducing the update_effective_progs() helper function.

The update_effective_progs() calls compute_effective_progs()
and then in case of success it calls activate_effective_progs()
for each descendant cgroup. In case of failure (OOM), it releases
allocated prog arrays and return the error code.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 0a4fe5a..6a7d931 100644 (file)
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -177,6 +177,45 @@ cleanup:
        return -ENOMEM;
 }
 
+static int update_effective_progs(struct cgroup *cgrp,
+                                 enum bpf_attach_type type)
+{
+       struct cgroup_subsys_state *css;
+       int err;
+
+       /* allocate and recompute effective prog arrays */
+       css_for_each_descendant_pre(css, &cgrp->self) {
+               struct cgroup *desc = container_of(css, struct cgroup, self);
+
+               err = compute_effective_progs(desc, type, &desc->bpf.inactive);
+               if (err)
+                       goto cleanup;
+       }
+
+       /* all allocations were successful. Activate all prog arrays */
+       css_for_each_descendant_pre(css, &cgrp->self) {
+               struct cgroup *desc = container_of(css, struct cgroup, self);
+
+               activate_effective_progs(desc, type, desc->bpf.inactive);
+               desc->bpf.inactive = NULL;
+       }
+
+       return 0;
+
+cleanup:
+       /* oom while computing effective. Free all computed effective arrays
+        * since they were not activated
+        */
+       css_for_each_descendant_pre(css, &cgrp->self) {
+               struct cgroup *desc = container_of(css, struct cgroup, self);
+
+               bpf_prog_array_free(desc->bpf.inactive);
+               desc->bpf.inactive = NULL;
+       }
+
+       return err;
+}
+
 #define BPF_CGROUP_MAX_PROGS 64
 
 /**
@@ -194,7 +233,6 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
        struct list_head *progs = &cgrp->bpf.progs[type];
        struct bpf_prog *old_prog = NULL;
        struct bpf_cgroup_storage *storage, *old_storage = NULL;
-       struct cgroup_subsys_state *css;
        struct bpf_prog_list *pl;
        bool pl_was_allocated;
        int err;
@@ -261,22 +299,9 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
 
        cgrp->bpf.flags[type] = flags;
 
-       /* allocate and recompute effective prog arrays */
-       css_for_each_descendant_pre(css, &cgrp->self) {
-               struct cgroup *desc = container_of(css, struct cgroup, self);
-
-               err = compute_effective_progs(desc, type, &desc->bpf.inactive);
-               if (err)
-                       goto cleanup;
-       }
-
-       /* all allocations were successful. Activate all prog arrays */
-       css_for_each_descendant_pre(css, &cgrp->self) {
-               struct cgroup *desc = container_of(css, struct cgroup, self);
-
-               activate_effective_progs(desc, type, desc->bpf.inactive);
-               desc->bpf.inactive = NULL;
-       }
+       err = update_effective_progs(cgrp, type);
+       if (err)
+               goto cleanup;
 
        static_branch_inc(&cgroup_bpf_enabled_key);
        if (old_storage)
@@ -289,16 +314,6 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
        return 0;
 
 cleanup:
-       /* oom while computing effective. Free all computed effective arrays
-        * since they were not activated
-        */
-       css_for_each_descendant_pre(css, &cgrp->self) {
-               struct cgroup *desc = container_of(css, struct cgroup, self);
-
-               bpf_prog_array_free(desc->bpf.inactive);
-               desc->bpf.inactive = NULL;
-       }
-
        /* and cleanup the prog list */
        pl->prog = old_prog;
        bpf_cgroup_storage_free(pl->storage);
@@ -326,7 +341,6 @@ int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
        struct list_head *progs = &cgrp->bpf.progs[type];
        u32 flags = cgrp->bpf.flags[type];
        struct bpf_prog *old_prog = NULL;
-       struct cgroup_subsys_state *css;
        struct bpf_prog_list *pl;
        int err;
 
@@ -365,22 +379,9 @@ int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
                pl->prog = NULL;
        }
 
-       /* allocate and recompute effective prog arrays */
-       css_for_each_descendant_pre(css, &cgrp->self) {
-               struct cgroup *desc = container_of(css, struct cgroup, self);
-
-               err = compute_effective_progs(desc, type, &desc->bpf.inactive);
-               if (err)
-                       goto cleanup;
-       }
-
-       /* all allocations were successful. Activate all prog arrays */
-       css_for_each_descendant_pre(css, &cgrp->self) {
-               struct cgroup *desc = container_of(css, struct cgroup, self);
-
-               activate_effective_progs(desc, type, desc->bpf.inactive);
-               desc->bpf.inactive = NULL;
-       }
+       err = update_effective_progs(cgrp, type);
+       if (err)
+               goto cleanup;
 
        /* now can actually delete it from this cgroup list */
        list_del(&pl->node);
@@ -396,16 +397,6 @@ int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
        return 0;
 
 cleanup:
-       /* oom while computing effective. Free all computed effective arrays
-        * since they were not activated
-        */
-       css_for_each_descendant_pre(css, &cgrp->self) {
-               struct cgroup *desc = container_of(css, struct cgroup, self);
-
-               bpf_prog_array_free(desc->bpf.inactive);
-               desc->bpf.inactive = NULL;
-       }
-
        /* and restore back old_prog */
        pl->prog = old_prog;
        return err;