Commit 9ddfa24e authored by Emil Tsalapatis's avatar Emil Tsalapatis Committed by Alexei Starovoitov
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bpf: Allow BPF stream kfuncs while holding a lock 



The BPF stream kfuncs bpf_stream_vprintk and bpf_stream_print_stack
do not sleep and so are safe to call while holding a lock. Amend
the verifier to allow that.

Signed-off-by: default avatarEmil Tsalapatis <emil@etsalapatis.com>
Acked-by: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260203180424.14057-4-emil@etsalapatis.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 954fa97e

kernel/bpf/verifier.c

+12 −1
Original line number Diff line number Diff line
@@ -12455,6 +12455,8 @@ enum special_kfunc_type { 
	KF_bpf_arena_free_pages,

	KF_bpf_arena_reserve_pages,

	KF_bpf_session_is_return,

	KF_bpf_stream_vprintk,

	KF_bpf_stream_print_stack,

};









BTF_ID_LIST(special_kfunc_list)








@@ -12533,6 +12535,8 @@ BTF_ID(func, bpf_arena_alloc_pages)







BTF_ID(func, bpf_arena_free_pages)









BTF_ID(func, bpf_arena_reserve_pages)









BTF_ID(func, bpf_session_is_return)









BTF_ID(func, bpf_stream_vprintk)









BTF_ID(func, bpf_stream_print_stack)

















static bool is_task_work_add_kfunc(u32 func_id)









{








@@ -12977,10 +12981,17 @@ static bool is_bpf_arena_kfunc(u32 btf_id)







	       btf_id == special_kfunc_list[KF_bpf_arena_reserve_pages];









}

















static bool is_bpf_stream_kfunc(u32 btf_id)









{









	return btf_id == special_kfunc_list[KF_bpf_stream_vprintk] ||









	       btf_id == special_kfunc_list[KF_bpf_stream_print_stack];









}

















static bool kfunc_spin_allowed(u32 btf_id)









{









	return is_bpf_graph_api_kfunc(btf_id) || is_bpf_iter_num_api_kfunc(btf_id) ||









	       is_bpf_res_spin_lock_kfunc(btf_id) || is_bpf_arena_kfunc(btf_id);









	       is_bpf_res_spin_lock_kfunc(btf_id) || is_bpf_arena_kfunc(btf_id) ||









	       is_bpf_stream_kfunc(btf_id);









}

















static bool is_sync_callback_calling_kfunc(u32 btf_id)