[14/14] bpf: Sort bpf kallsyms symbols
diff mbox series

Message ID 20200208154209.1797988-15-jolsa@kernel.org
State Superseded
Delegated to: BPF Maintainers
Headers show
Series
  • bpf: Add trampoline and dispatcher to /proc/kallsyms
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Commit Message

Jiri Olsa Feb. 8, 2020, 3:42 p.m. UTC
Currently we don't sort bpf_kallsyms and display symbols
in proc/kallsyms as they come in via __bpf_ksym_add.

Using the latch tree to get the next bpf_ksym object
and insert the new symbol ahead of it.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/bpf/core.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

Comments

Andrii Nakryiko Feb. 11, 2020, 7:12 p.m. UTC | #1
On Sat, Feb 8, 2020 at 7:43 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Currently we don't sort bpf_kallsyms and display symbols
> in proc/kallsyms as they come in via __bpf_ksym_add.
>
> Using the latch tree to get the next bpf_ksym object
> and insert the new symbol ahead of it.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---

Acked-by: Andrii Nakryiko <andriin@fb.com>

>  kernel/bpf/core.c | 23 ++++++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index 50af5dcf7ff9..c63ff34b2128 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -651,9 +651,30 @@ static struct latch_tree_root bpf_progs_tree __cacheline_aligned;
>
>  static void __bpf_ksym_add(struct bpf_ksym *ksym)
>  {
> +       struct list_head *head = &bpf_kallsyms;
> +
>         WARN_ON_ONCE(!list_empty(&ksym->lnode));
> -       list_add_tail_rcu(&ksym->lnode, &bpf_kallsyms);
>         latch_tree_insert(&ksym->tnode, &bpf_kallsyms_tree, &bpf_kallsyms_tree_ops);
> +
> +       /*
> +        * Add ksym into bpf_kallsyms in ordered position,
> +        * which is prepared for us by latch tree addition.
> +        *
> +        * Find out the next symbol and insert ksym right
> +        * ahead of it. If ksym is the last one, just tail
> +        * add to the bpf_kallsyms.
> +        */
> +       if (!list_empty(&bpf_kallsyms)) {

nit: this is a bit redundant check (and unlikely to be false)

> +               struct rb_node *next = rb_next(&ksym->tnode.node[0]);
> +
> +               if (next) {
> +                       struct bpf_ksym *ptr;
> +
> +                       ptr = container_of(next, struct bpf_ksym, tnode.node[0]);
> +                       head = &ptr->lnode;
> +               }
> +       }
> +       list_add_tail_rcu(&ksym->lnode, head);
>  }
>
>  void bpf_ksym_add(struct bpf_ksym *ksym)
> --
> 2.24.1
>

Patch
diff mbox series

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 50af5dcf7ff9..c63ff34b2128 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -651,9 +651,30 @@  static struct latch_tree_root bpf_progs_tree __cacheline_aligned;
 
 static void __bpf_ksym_add(struct bpf_ksym *ksym)
 {
+	struct list_head *head = &bpf_kallsyms;
+
 	WARN_ON_ONCE(!list_empty(&ksym->lnode));
-	list_add_tail_rcu(&ksym->lnode, &bpf_kallsyms);
 	latch_tree_insert(&ksym->tnode, &bpf_kallsyms_tree, &bpf_kallsyms_tree_ops);
+
+	/*
+	 * Add ksym into bpf_kallsyms in ordered position,
+	 * which is prepared for us by latch tree addition.
+	 *
+	 * Find out the next symbol and insert ksym right
+	 * ahead of it. If ksym is the last one, just tail
+	 * add to the bpf_kallsyms.
+	 */
+	if (!list_empty(&bpf_kallsyms)) {
+		struct rb_node *next = rb_next(&ksym->tnode.node[0]);
+
+		if (next) {
+			struct bpf_ksym *ptr;
+
+			ptr = container_of(next, struct bpf_ksym, tnode.node[0]);
+			head = &ptr->lnode;
+		}
+	}
+	list_add_tail_rcu(&ksym->lnode, head);
 }
 
 void bpf_ksym_add(struct bpf_ksym *ksym)