Commit 8a7dac37 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Alexei Starovoitov
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bpf: Add new bpf_task_storage_delete proto with no deadlock detection 



The bpf_lsm and bpf_iter do not recur that will cause a deadlock.
The situation is similar to the bpf_pid_task_storage_delete_elem()
which is called from the syscall map_delete_elem.  It does not need
deadlock detection.  Otherwise, it will cause unnecessary failure
when calling the bpf_task_storage_delete() helper.

This patch adds bpf_task_storage_delete proto that does not do deadlock
detection.  It will be used by bpf_lsm and bpf_iter program.

Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20221025184524.3526117-8-martin.lau@linux.dev


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent fda64ae0

include/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -2522,6 +2522,7 @@ extern const struct bpf_func_proto bpf_get_socket_ptr_cookie_proto; 
extern const struct bpf_func_proto bpf_task_storage_get_recur_proto;

extern const struct bpf_func_proto bpf_task_storage_get_proto;

extern const struct bpf_func_proto bpf_task_storage_delete_recur_proto;

extern const struct bpf_func_proto bpf_task_storage_delete_proto;

extern const struct bpf_func_proto bpf_for_each_map_elem_proto;

extern const struct bpf_func_proto bpf_btf_find_by_name_kind_proto;

extern const struct bpf_func_proto bpf_sk_setsockopt_proto;

kernel/bpf/bpf_task_storage.c

+28 −0
Original line number Diff line number Diff line
@@ -311,6 +311,25 @@ BPF_CALL_2(bpf_task_storage_delete_recur, struct bpf_map *, map, struct task_str 
	return ret;

}



BPF_CALL_2(bpf_task_storage_delete, struct bpf_map *, map, struct task_struct *,

	   task)

{

	int ret;



	WARN_ON_ONCE(!bpf_rcu_lock_held());

	if (!task)

		return -EINVAL;



	bpf_task_storage_lock();

	/* This helper must only be called from places where the lifetime of the task

	 * is guaranteed. Either by being refcounted or by being protected

	 * by an RCU read-side critical section.

	 */

	ret = task_storage_delete(task, map, true);

	bpf_task_storage_unlock();

	return ret;

}



static int notsupp_get_next_key(struct bpf_map *map, void *key, void *next_key)

{

	return -ENOTSUPP;
@@ -382,3 +401,12 @@ const struct bpf_func_proto bpf_task_storage_delete_recur_proto = { 
	.arg2_type = ARG_PTR_TO_BTF_ID,

	.arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],

};



const struct bpf_func_proto bpf_task_storage_delete_proto = {

	.func = bpf_task_storage_delete,

	.gpl_only = false,

	.ret_type = RET_INTEGER,

	.arg1_type = ARG_CONST_MAP_PTR,

	.arg2_type = ARG_PTR_TO_BTF_ID,

	.arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],

};

kernel/trace/bpf_trace.c

+3 −1
Original line number Diff line number Diff line
@@ -1493,7 +1493,9 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 
			return &bpf_task_storage_get_recur_proto;

		return &bpf_task_storage_get_proto;

	case BPF_FUNC_task_storage_delete:

		if (bpf_prog_check_recur(prog))

			return &bpf_task_storage_delete_recur_proto;

		return &bpf_task_storage_delete_proto;

	case BPF_FUNC_for_each_map_elem:

		return &bpf_for_each_map_elem_proto;

	case BPF_FUNC_snprintf: