netdev - [PATCH bpf-next 2/8] bpf: add for_each_bpf

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Message-Id: <20210216105713.45052-3-lmb@cloudflare.com>
Date:   Tue, 16 Feb 2021 10:57:07 +0000
From:   Lorenz Bauer <lmb@...udflare.com>
To:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
        jakub@...udflare.com
Cc:     kernel-team@...udflare.com, bpf@...r.kernel.org,
        netdev@...r.kernel.org, Lorenz Bauer <lmb@...udflare.com>
Subject: [PATCH bpf-next 2/8] bpf: add for_each_bpf_prog helper

Add a helper to iterate bpf_prog_arrays, which are a hybrid between
and array and a linked list. Hide this behind a for each macro.

Signed-off-by: Lorenz Bauer <lmb@...udflare.com>
---
 include/linux/bpf.h    | 11 +++++------
 include/linux/filter.h |  4 +---
 2 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index cccaef1088ea..875f6bc4bf1d 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1070,6 +1070,9 @@ int bpf_prog_array_copy(struct bpf_prog_array *old_array,
 /* BPF program asks to set CN on the packet. */
 #define BPF_RET_SET_CN						(1 << 0)
 
+#define for_each_bpf_prog(_array, _item, _prog) \
+	for ((_item) = &(_array)->items[0]; ((_prog) = READ_ONCE((_item)->prog)); (_item)++)
+
 #define BPF_PROG_RUN_ARRAY_FLAGS(array, ctx, func, ret_flags)		\
 	({								\
 		struct bpf_prog_array_item *_item;			\
@@ -1080,13 +1083,11 @@ int bpf_prog_array_copy(struct bpf_prog_array *old_array,
 		migrate_disable();					\
 		rcu_read_lock();					\
 		_array = rcu_dereference(array);			\
-		_item = &_array->items[0];				\
-		while ((_prog = READ_ONCE(_item->prog))) {		\
+		for_each_bpf_prog(_array, _item, _prog) {		\
 			bpf_cgroup_storage_set(_item->cgroup_storage);	\
 			func_ret = func(_prog, ctx);			\
 			_ret &= (func_ret & 1);				\
 			*(ret_flags) |= (func_ret >> 1);			\
-			_item++;					\
 		}							\
 		rcu_read_unlock();					\
 		migrate_enable();					\
@@ -1104,11 +1105,9 @@ int bpf_prog_array_copy(struct bpf_prog_array *old_array,
 		_array = rcu_dereference(array);	\
 		if (unlikely(check_non_null && !_array))\
 			goto _out;			\
-		_item = &_array->items[0];		\
-		while ((_prog = READ_ONCE(_item->prog))) {		\
+		for_each_bpf_prog(_array, _item, _prog) {		\
 			bpf_cgroup_storage_set(_item->cgroup_storage);	\
 			_ret &= func(_prog, ctx);	\
-			_item++;			\
 		}					\
 _out:							\
 		rcu_read_unlock();			\
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 3b00fc906ccd..9ed20ff29d9a 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -1376,8 +1376,7 @@ extern struct static_key_false bpf_sk_lookup_enabled;
 		u32 _ret;						\
 									\
 		migrate_disable();					\
-		_item = &(array)->items[0];				\
-		while ((_prog = READ_ONCE(_item->prog))) {		\
+		for_each_bpf_prog(array, _item, _prog) {		\
 			/* restore most recent selection */		\
 			_ctx->selected_sk = _selected_sk;		\
 			_ctx->no_reuseport = _no_reuseport;		\
@@ -1390,7 +1389,6 @@ extern struct static_key_false bpf_sk_lookup_enabled;
 			} else if (_ret == SK_DROP && _all_pass) {	\
 				_all_pass = false;			\
 			}						\
-			_item++;					\
 		}							\
 		_ctx->selected_sk = _selected_sk;			\
 		_ctx->no_reuseport = _no_reuseport;			\
-- 
2.27.0