diff mbox series

[bpf-next,v4,1/8] btf: Add a new kfunc set which allows to mark a function to be sleepable

Message ID 20220722021313.3150035-2-yosryahmed@google.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series bpf: rstat: cgroup hierarchical stats | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/apply fail Patch does not apply to bpf-next
bpf/vmtest-bpf-next-PR fail PR summary
bpf/vmtest-bpf-next-VM_Test-1 success Logs for Kernel LATEST on ubuntu-latest with gcc
bpf/vmtest-bpf-next-VM_Test-2 success Logs for Kernel LATEST on ubuntu-latest with llvm-15
bpf/vmtest-bpf-next-VM_Test-3 fail Logs for Kernel LATEST on z15 with gcc

Commit Message

Yosry Ahmed July 22, 2022, 2:13 a.m. UTC 
From: Benjamin Tissoires <benjamin.tissoires@redhat.com>

This allows to declare a kfunc as sleepable and prevents its use in
a non sleepable program.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
---
 include/linux/btf.h |  2 ++
 kernel/bpf/btf.c    | 13 +++++++++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

Comments

Alexei Starovoitov July 22, 2022, 4:20 p.m. UTC | #1 
On Thu, Jul 21, 2022 at 7:13 PM Yosry Ahmed <yosryahmed@google.com> wrote:
>
> From: Benjamin Tissoires <benjamin.tissoires@redhat.com>
>
> This allows to declare a kfunc as sleepable and prevents its use in
> a non sleepable program.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
> Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
> ---
>  include/linux/btf.h |  2 ++
>  kernel/bpf/btf.c    | 13 +++++++++++--
>  2 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/btf.h b/include/linux/btf.h
> index 1bfed7fa0428..6e7517573d9e 100644
> --- a/include/linux/btf.h
> +++ b/include/linux/btf.h
> @@ -18,6 +18,7 @@ enum btf_kfunc_type {
>         BTF_KFUNC_TYPE_RELEASE,
>         BTF_KFUNC_TYPE_RET_NULL,
>         BTF_KFUNC_TYPE_KPTR_ACQUIRE,
> +       BTF_KFUNC_TYPE_SLEEPABLE,
>         BTF_KFUNC_TYPE_MAX,
>  };

This patch needs refactoring using the new BTF_ID_FLAGS scheme.
When you do that please update the Documentation/bpf/kfuncs.rst as well.

Thanks!
Yosry Ahmed July 22, 2022, 5:49 p.m. UTC | #2 
On Fri, Jul 22, 2022 at 9:20 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Thu, Jul 21, 2022 at 7:13 PM Yosry Ahmed <yosryahmed@google.com> wrote:
> >
> > From: Benjamin Tissoires <benjamin.tissoires@redhat.com>
> >
> > This allows to declare a kfunc as sleepable and prevents its use in
> > a non sleepable program.
> >
> > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
> > Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
> > ---
> >  include/linux/btf.h |  2 ++
> >  kernel/bpf/btf.c    | 13 +++++++++++--
> >  2 files changed, 13 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/btf.h b/include/linux/btf.h
> > index 1bfed7fa0428..6e7517573d9e 100644
> > --- a/include/linux/btf.h
> > +++ b/include/linux/btf.h
> > @@ -18,6 +18,7 @@ enum btf_kfunc_type {
> >         BTF_KFUNC_TYPE_RELEASE,
> >         BTF_KFUNC_TYPE_RET_NULL,
> >         BTF_KFUNC_TYPE_KPTR_ACQUIRE,
> > +       BTF_KFUNC_TYPE_SLEEPABLE,
> >         BTF_KFUNC_TYPE_MAX,
> >  };
>
> This patch needs refactoring using the new BTF_ID_FLAGS scheme.
> When you do that please update the Documentation/bpf/kfuncs.rst as well.
>
> Thanks!

Sent v5 rebased on top of the new kfunc flags infrastructure, and
added documentation for sleepable kfuncs.
diff mbox series

Patch

diff --git a/include/linux/btf.h b/include/linux/btf.h
index 1bfed7fa0428..6e7517573d9e 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -18,6 +18,7 @@  enum btf_kfunc_type {
 	BTF_KFUNC_TYPE_RELEASE,
 	BTF_KFUNC_TYPE_RET_NULL,
 	BTF_KFUNC_TYPE_KPTR_ACQUIRE,
+	BTF_KFUNC_TYPE_SLEEPABLE,
 	BTF_KFUNC_TYPE_MAX,
 };
 
@@ -37,6 +38,7 @@  struct btf_kfunc_id_set {
 			struct btf_id_set *release_set;
 			struct btf_id_set *ret_null_set;
 			struct btf_id_set *kptr_acquire_set;
+			struct btf_id_set *sleepable_set;
 		};
 		struct btf_id_set *sets[BTF_KFUNC_TYPE_MAX];
 	};
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 5869f03bcb6e..2040e440f347 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6178,7 +6178,7 @@  static int btf_check_func_arg_match(struct bpf_verifier_env *env,
 	struct bpf_verifier_log *log = &env->log;
 	u32 i, nargs, ref_id, ref_obj_id = 0;
 	bool is_kfunc = btf_is_kernel(btf);
-	bool rel = false, kptr_get = false;
+	bool rel = false, kptr_get = false, sleepable = false;
 	const char *func_name, *ref_tname;
 	const struct btf_type *t, *ref_t;
 	const struct btf_param *args;
@@ -6209,11 +6209,13 @@  static int btf_check_func_arg_match(struct bpf_verifier_env *env,
 	}
 
 	if (is_kfunc) {
-		/* Only kfunc can be release func */
+		/* Only kfunc can be release, kptr acquire, or sleepable func */
 		rel = btf_kfunc_id_set_contains(btf, resolve_prog_type(env->prog),
 						BTF_KFUNC_TYPE_RELEASE, func_id);
 		kptr_get = btf_kfunc_id_set_contains(btf, resolve_prog_type(env->prog),
 						     BTF_KFUNC_TYPE_KPTR_ACQUIRE, func_id);
+		sleepable = btf_kfunc_id_set_contains(btf, resolve_prog_type(env->prog),
+						      BTF_KFUNC_TYPE_SLEEPABLE, func_id);
 	}
 
 	/* check that BTF function arguments match actual types that the
@@ -6411,6 +6413,13 @@  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;
 }