> From: Hao Luo [mailto:haoluo@xxxxxxxxxx] > Sent: Monday, August 1, 2022 7:54 PM > From: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> > > From: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> > > This allows to declare a kfunc as sleepable and prevents its use in > a non sleepable program. > > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> > Co-developed-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx> > Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx> > Signed-off-by: Hao Luo <haoluo@xxxxxxxxxx> Thanks, helpful also for me. Reviewed-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx> Roberto > --- > Documentation/bpf/kfuncs.rst | 6 ++++++ > include/linux/btf.h | 1 + > kernel/bpf/btf.c | 9 +++++++++ > 3 files changed, 16 insertions(+) > > diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst > index c0b7dae6dbf5..c8b21de1c772 100644 > --- a/Documentation/bpf/kfuncs.rst > +++ b/Documentation/bpf/kfuncs.rst > @@ -146,6 +146,12 @@ that operate (change some property, perform some > operation) on an object that > was obtained using an acquire kfunc. Such kfuncs need an unchanged pointer to > ensure the integrity of the operation being performed on the expected object. > > +2.4.6 KF_SLEEPABLE flag > +----------------------- > + > +The KF_SLEEPABLE flag is used for kfuncs that may sleep. Such kfuncs can only > +be called by sleepable BPF programs (BPF_F_SLEEPABLE). > + > 2.5 Registering the kfuncs > -------------------------- > > diff --git a/include/linux/btf.h b/include/linux/btf.h > index cdb376d53238..976cbdd2981f 100644 > --- a/include/linux/btf.h > +++ b/include/linux/btf.h > @@ -49,6 +49,7 @@ > * for this case. > */ > #define KF_TRUSTED_ARGS (1 << 4) /* kfunc only takes trusted pointer > arguments */ > +#define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */ > > struct btf; > struct btf_member; > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > index 7e64447659f3..d3e4c86b8fcd 100644 > --- a/kernel/bpf/btf.c > +++ b/kernel/bpf/btf.c > @@ -6175,6 +6175,7 @@ static int btf_check_func_arg_match(struct > bpf_verifier_env *env, > { > enum bpf_prog_type prog_type = resolve_prog_type(env->prog); > bool rel = false, kptr_get = false, trusted_arg = false; > + bool sleepable = false; > struct bpf_verifier_log *log = &env->log; > u32 i, nargs, ref_id, ref_obj_id = 0; > bool is_kfunc = btf_is_kernel(btf); > @@ -6212,6 +6213,7 @@ static int btf_check_func_arg_match(struct > bpf_verifier_env *env, > rel = kfunc_flags & KF_RELEASE; > kptr_get = kfunc_flags & KF_KPTR_GET; > trusted_arg = kfunc_flags & KF_TRUSTED_ARGS; > + sleepable = kfunc_flags & KF_SLEEPABLE; > } > > /* check that BTF function arguments match actual types that the > @@ -6419,6 +6421,13 @@ static int btf_check_func_arg_match(struct > bpf_verifier_env *env, > func_name); > return -EINVAL; > } > + > + if (sleepable && !env->prog->aux->sleepable) { > + bpf_log(log, "kernel function %s is sleepable but the program is > not\n", > + func_name); > + return -EINVAL; > + } > + > /* returns argument register number > 0 in case of reference release > kfunc */ > return rel ? ref_regno : 0; > } > -- > 2.37.1.455.g008518b4e5-goog
