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Diffstat (limited to 'Documentation/bpf/kfuncs.rst')
| -rw-r--r-- | Documentation/bpf/kfuncs.rst | 36 |
1 files changed, 35 insertions, 1 deletions
diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst index a8f5782bd833..e38941370b90 100644 --- a/Documentation/bpf/kfuncs.rst +++ b/Documentation/bpf/kfuncs.rst @@ -160,6 +160,23 @@ Or:: ... } +2.2.6 __prog Annotation +--------------------------- +This annotation is used to indicate that the argument needs to be fixed up to +the bpf_prog_aux of the caller BPF program. Any value passed into this argument +is ignored, and rewritten by the verifier. + +An example is given below:: + + __bpf_kfunc int bpf_wq_set_callback_impl(struct bpf_wq *wq, + int (callback_fn)(void *map, int *key, void *value), + unsigned int flags, + void *aux__prog) + { + struct bpf_prog_aux *aux = aux__prog; + ... + } + .. _BPF_kfunc_nodef: 2.3 Using an existing kernel function @@ -318,9 +335,26 @@ consider doing refcnt != 0 check, especially when returning a KF_ACQUIRE pointer. Note as well that a KF_ACQUIRE kfunc that is KF_RCU should very likely also be KF_RET_NULL. +2.4.8 KF_RCU_PROTECTED flag +--------------------------- + +The KF_RCU_PROTECTED flag is used to indicate that the kfunc must be invoked in +an RCU critical section. This is assumed by default in non-sleepable programs, +and must be explicitly ensured by calling ``bpf_rcu_read_lock`` for sleepable +ones. + +If the kfunc returns a pointer value, this flag also enforces that the returned +pointer is RCU protected, and can only be used while the RCU critical section is +active. + +The flag is distinct from the ``KF_RCU`` flag, which only ensures that its +arguments are at least RCU protected pointers. This may transitively imply that +RCU protection is ensured, but it does not work in cases of kfuncs which require +RCU protection but do not take RCU protected arguments. + .. _KF_deprecated_flag: -2.4.8 KF_DEPRECATED flag +2.4.9 KF_DEPRECATED flag ------------------------ The KF_DEPRECATED flag is used for kfuncs which are scheduled to be |