Commit e9c856ca authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
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bpf: put uprobe link's path and task in release callback 



There is no need to delay putting either path or task to deallocation
step. It can be done right after bpf_uprobe_unregister. Between release
and dealloc, there could be still some running BPF programs, but they
don't access either task or path, only data in link->uprobes, so it is
safe to do.

On the other hand, doing path_put() in dealloc callback makes this
dealloc sleepable because path_put() itself might sleep. Which is
problematic due to the need to call uprobe's dealloc through call_rcu(),
which is what is done in the next bug fix patch. So solve the problem by
releasing these resources early.

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240328052426.3042617-1-andrii@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 03796540

kernel/trace/bpf_trace.c

+3 −3
Original line number Diff line number Diff line
@@ -3157,6 +3157,9 @@ static void bpf_uprobe_multi_link_release(struct bpf_link *link) 


	umulti_link = container_of(link, struct bpf_uprobe_multi_link, link);

	bpf_uprobe_unregister(&umulti_link->path, umulti_link->uprobes, umulti_link->cnt);

	if (umulti_link->task)

		put_task_struct(umulti_link->task);

	path_put(&umulti_link->path);

}



static void bpf_uprobe_multi_link_dealloc(struct bpf_link *link)
@@ -3164,9 +3167,6 @@ static void bpf_uprobe_multi_link_dealloc(struct bpf_link *link) 
	struct bpf_uprobe_multi_link *umulti_link;



	umulti_link = container_of(link, struct bpf_uprobe_multi_link, link);

	if (umulti_link->task)

		put_task_struct(umulti_link->task);

	path_put(&umulti_link->path);

	kvfree(umulti_link->uprobes);

	kfree(umulti_link);

}