Fix script loading synchronization issue

Author: VictorNogueiraRio

include/linux/filter.h

@@ -1229,14 +1229,4 @@ struct bpf_sockopt_kern {
 	s32		retval;
 };
 
-#ifdef CONFIG_XDP_LUA
-extern struct list_head lua_state_cpu_list;
-
-struct lua_state_cpu {
-	struct lua_State 	*L;
-	int			cpu;
-	struct list_head	list;
-};
-#endif /* CONFIG_XDP_LUA */
-
 #endif /* __LINUX_FILTER_H__ */

include/net/xdp.h

@@ -63,6 +63,15 @@ struct xdp_rxq_info {
 	struct xdp_mem_info mem;
 } ____cacheline_aligned; /* perf critical, avoid false-sharing */
 
+#ifdef CONFIG_XDP_LUA
+struct xdplua {
+	struct lua_State	*L;
+	spinlock_t		*lock;
+};
+
+DECLARE_PER_CPU(struct xdplua, xdplua_per_cpu);
+#endif /* CONFIG_XDP_LUA */
+
 struct xdp_buff {
 	void *data;
 	void *data_end;
@@ -72,7 +81,7 @@ struct xdp_buff {
 	struct xdp_rxq_info *rxq;
 #ifdef CONFIG_XDP_LUA
 	struct sk_buff *skb;
-	struct lua_State *L;
+	struct xdplua *xdplua;
 #endif /* CONFIG_XDP_LUA */
 };
 

include/uapi/linux/bpf.h

@@ -2836,9 +2836,10 @@ union bpf_attr {
 	FN(lua_pushmap),		\
 	FN(lua_pushskb),		\
 	FN(lua_pushstring),		\
-	FN(lua_setstate),		\
 	FN(lua_toboolean),		\
-	FN(lua_tointeger),
+	FN(lua_tointeger),		\
+	FN(lua_putstate),		\
+	FN(lua_removestate),
 	/* #endif CONFIG_XDP_LUA */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper

net/core/dev.c

@@ -159,6 +159,9 @@
 
 static DEFINE_SPINLOCK(ptype_lock);
 static DEFINE_SPINLOCK(offload_lock);
+#ifdef CONFIG_XDP_LUA
+static DEFINE_PER_CPU(spinlock_t, lua_state_lock);
+#endif
 struct list_head ptype_base[PTYPE_HASH_SIZE] __read_mostly;
 struct list_head ptype_all __read_mostly;	/* Taps */
 static struct list_head offload_base __read_mostly;
@@ -171,10 +174,6 @@ static int call_netdevice_notifiers_extack(unsigned long val,
 					   struct netlink_ext_ack *extack);
 static struct napi_struct *napi_by_id(unsigned int napi_id);
 
-#ifdef CONFIG_XDP_LUA
-struct list_head lua_state_cpu_list;
-#endif /* CONFIG_XDP_LUA */
-
 /*
  * The @dev_base_head list is protected by @dev_base_lock and the rtnl
  * semaphore.
@@ -5198,16 +5197,24 @@ static int generic_xdp_install(struct net_device *dev, struct netdev_bpf *xdp)
 }
 
 #ifdef CONFIG_XDP_LUA
+DEFINE_PER_CPU(struct xdplua, xdplua_per_cpu);
+
 int generic_xdp_lua_install_prog(char *lua_prog)
 {
-	struct lua_state_cpu *sc;
+	struct xdplua *sc;
+	int i;
 
-	list_for_each_entry(sc, &lua_state_cpu_list, list) {
+	for_each_possible_cpu(i) {
+		sc = per_cpu_ptr(&xdplua_per_cpu, i);
+		spin_lock_bh(sc->lock);
 		if (luaL_dostring(sc->L, lua_prog)) {
 			pr_err(KERN_INFO "error: %s\nOn cpu: %d\n",
-				lua_tostring(sc->L, -1), sc->cpu);
+				lua_tostring(sc->L, -1), i);
+			spin_unlock_bh(sc->lock);
 			return -EINVAL;
 		}
+
+		spin_unlock_bh(sc->lock);
 	}
 	return 0;
 }
@@ -9830,9 +9837,6 @@ static struct pernet_operations __net_initdata default_device_ops = {
 static int __init net_dev_init(void)
 {
 	int i, rc = -ENOMEM;
-#ifdef CONFIG_XDP_LUA
-	struct lua_state_cpu *new_state_cpu;
-#endif /* CONFIG_XDP_LUA */
 
 	BUG_ON(!dev_boot_phase);
 
@@ -9847,9 +9851,6 @@ static int __init net_dev_init(void)
 		INIT_LIST_HEAD(&ptype_base[i]);
 
 	INIT_LIST_HEAD(&offload_base);
-#ifdef CONFIG_XDP_LUA
-	INIT_LIST_HEAD(&lua_state_cpu_list);
-#endif /* CONFIG_XDP_LUA */
 
 	if (register_pernet_subsys(&netdev_net_ops))
 		goto out;
@@ -9861,6 +9862,7 @@ static int __init net_dev_init(void)
 	for_each_possible_cpu(i) {
 		struct work_struct *flush = per_cpu_ptr(&flush_works, i);
 		struct softnet_data *sd = &per_cpu(softnet_data, i);
+		struct xdplua *xdplua = per_cpu_ptr(&xdplua_per_cpu, i);
 
 		INIT_WORK(flush, flush_backlog);
 
@@ -9880,25 +9882,17 @@ static int __init net_dev_init(void)
 		init_gro_hash(&sd->backlog);
 		sd->backlog.poll = process_backlog;
 		sd->backlog.weight = weight_p;
-
 #ifdef CONFIG_XDP_LUA
-		new_state_cpu = (struct lua_state_cpu *)
-			kmalloc(sizeof(struct lua_state_cpu), GFP_ATOMIC);
-		if (!new_state_cpu)
-			continue;
-
-		new_state_cpu->L = luaL_newstate();
-		if  (!new_state_cpu->L) {
-			kfree(new_state_cpu);
+		xdplua->L = luaL_newstate();
+		if  (!xdplua->L) {
+			kfree(xdplua);
 			continue;
 		}
 
-		luaL_openlibs(new_state_cpu->L);
-		luaL_requiref(new_state_cpu->L, "data", luaopen_data, 1);
-		lua_pop(new_state_cpu->L, 1);
-		new_state_cpu->cpu = i;
-
-		list_add(&new_state_cpu->list, &lua_state_cpu_list);
+		luaL_openlibs(xdplua->L);
+		luaL_requiref(xdplua->L, "data", luaopen_data, 1);
+		lua_pop(xdplua->L, 1);
+		xdplua->lock = per_cpu_ptr(&lua_state_lock, i);
 #endif /* CONFIG_XDP_LUA */
 	}
 

net/core/filter.c

@@ -5862,7 +5862,7 @@ BPF_CALL_2(bpf_lua_dataref, struct xdp_buff *, ctx, int, offset) {
 	if (offset + ctx->data < ctx->data_end) {
 		int data_ref;
 
-		data_ref = ldata_newref(ctx->L, ctx->data + offset,
+		data_ref = ldata_newref(ctx->xdplua->L, ctx->data + offset,
 				ctx->data_end - ctx->data - offset);
 		return data_ref;
 	}
@@ -5880,7 +5880,7 @@ static const struct bpf_func_proto bpf_lua_dataref_proto = {
 };
 
 BPF_CALL_2(bpf_lua_dataunref, struct xdp_buff *, ctx, int, data_ref) {
-	ldata_unref(ctx->L, data_ref);
+	ldata_unref(ctx->xdplua->L, data_ref);
 	return 0;
 }
 
@@ -5895,16 +5895,16 @@ static const struct bpf_func_proto bpf_lua_dataunref_proto = {
 
 BPF_CALL_4(bpf_lua_pcall, struct xdp_buff *, ctx, char *, funcname,
 			int, num_args, int, num_rets) {
-	if (lua_getglobal(ctx->L, funcname) != LUA_TFUNCTION) {
+	if (lua_getglobal(ctx->xdplua->L, funcname) != LUA_TFUNCTION) {
 		pr_err("function %s not found\n", funcname);
-		lua_pop(ctx->L, num_args);
+		lua_pop(ctx->xdplua->L, num_args);
 		return 0;
 	}
 
-	lua_insert(ctx->L, 1);
-	if (lua_pcall(ctx->L, num_args, num_rets, 0)) {
-		pr_err("%s\n", lua_tostring(ctx->L, -1));
-		lua_pop(ctx->L, 1);
+	lua_insert(ctx->xdplua->L, 1);
+	if (lua_pcall(ctx->xdplua->L, num_args, num_rets, 0)) {
+		pr_err("%s\n", lua_tostring(ctx->xdplua->L, -1));
+		lua_pop(ctx->xdplua->L, 1);
 		return 0;
 	}
 	return num_rets;
@@ -5922,7 +5922,7 @@ static const struct bpf_func_proto bpf_lua_pcall_proto = {
 };
 
 BPF_CALL_2(bpf_lua_pop, struct xdp_buff *, ctx, int, index) {
-	lua_pop(ctx->L, index);
+	lua_pop(ctx->xdplua->L, index);
 	return 0;
 }
 
@@ -5936,7 +5936,7 @@ static const struct bpf_func_proto bpf_lua_pop_proto = {
 };
 
 BPF_CALL_2(bpf_lua_pushinteger, struct xdp_buff *, ctx, int, num) {
-	lua_pushinteger(ctx->L, num);
+	lua_pushinteger(ctx->xdplua->L, num);
 	return 0;
 }
 
@@ -5950,7 +5950,7 @@ static const struct bpf_func_proto bpf_lua_pushinteger_proto = {
 };
 
 BPF_CALL_2(bpf_lua_pushlightuserdata, struct xdp_buff *, ctx, void *, ptr) {
-	lua_pushlightuserdata(ctx->L, ptr);
+	lua_pushlightuserdata(ctx->xdplua->L, ptr);
 	return 0;
 }
 
@@ -5964,12 +5964,12 @@ static const struct bpf_func_proto bpf_lua_pushlightuserdata_proto = {
 };
 
 BPF_CALL_2(bpf_lua_pushmap, struct xdp_buff *, ctx, struct bpf_map *, map) {
-	lua_pushlightuserdata(ctx->L, map);
+	lua_pushlightuserdata(ctx->xdplua->L, map);
 	return 0;
 }
 
 BPF_CALL_3(bpf_lua_pushlstring, struct xdp_buff *, ctx, const char *, str, size_t, len) {
-	lua_pushlstring(ctx->L, str, len);
+	lua_pushlstring(ctx->xdplua->L, str, len);
 	return 0;
 }
 
@@ -5993,7 +5993,7 @@ static const struct bpf_func_proto bpf_lua_pushmap_proto = {
 };
 
 BPF_CALL_1(bpf_lua_pushskb, struct xdp_buff *, ctx) {
-	lua_pushlightuserdata(ctx->L, ctx->skb);
+	lua_pushlightuserdata(ctx->xdplua->L, ctx->skb);
 	return 0;
 }
 
@@ -6006,7 +6006,7 @@ static const struct bpf_func_proto bpf_lua_pushskb_proto = {
 };
 
 BPF_CALL_2(bpf_lua_pushstring, struct xdp_buff *, ctx, const char *, str) {
-	lua_pushstring(ctx->L, str);
+	lua_pushstring(ctx->xdplua->L, str);
 	return 0;
 }
 
@@ -6019,29 +6019,8 @@ static const struct bpf_func_proto bpf_lua_pushstring_proto = {
 	.arg2_type	= ARG_ANYTHING,
 };
 
-BPF_CALL_1(bpf_lua_setstate, struct xdp_buff *, ctx){
-	struct lua_state_cpu *sc;
-	int cpu = smp_processor_id();
-
-	list_for_each_entry(sc, &lua_state_cpu_list, list) {
-		if (sc->cpu == cpu) {
-			ctx->L = sc->L;
-			break;
-		}
-	}
-	return 0;
-}
-
-static const struct bpf_func_proto bpf_lua_setstate_proto = {
-	.func		= bpf_lua_setstate,
-	.gpl_only	= false,
-	.pkt_access	= false,
-	.ret_type	= RET_VOID,
-	.arg1_type	= ARG_PTR_TO_CTX,
-};
-
 BPF_CALL_2(bpf_lua_toboolean, struct xdp_buff *, ctx, int, index) {
-	return lua_toboolean(ctx->L, index);
+	return lua_toboolean(ctx->xdplua->L, index);
 }
 
 static const struct bpf_func_proto bpf_lua_toboolean_proto = {
@@ -6054,7 +6033,7 @@ static const struct bpf_func_proto bpf_lua_toboolean_proto = {
 };
 
 BPF_CALL_2(bpf_lua_tointeger, struct xdp_buff *, ctx, int, index) {
-	return lua_tointeger(ctx->L, index);
+	return lua_tointeger(ctx->xdplua->L, index);
 }
 
 static const struct bpf_func_proto bpf_lua_tointeger_proto = {
@@ -6065,6 +6044,34 @@ static const struct bpf_func_proto bpf_lua_tointeger_proto = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
 };
+
+BPF_CALL_1(bpf_lua_putstate, struct xdp_buff *, ctx) {
+	ctx->xdplua = this_cpu_ptr(&xdplua_per_cpu);
+	spin_lock(ctx->xdplua->lock);
+	return 0;
+}
+
+static const struct bpf_func_proto bpf_lua_putstate_proto = {
+	.func		= bpf_lua_putstate,
+	.gpl_only	= false,
+	.pkt_access	= false,
+	.ret_type	= RET_VOID,
+	.arg1_type	= ARG_PTR_TO_CTX,
+};
+
+BPF_CALL_1(bpf_lua_removestate, struct xdp_buff *, ctx) {
+	spin_unlock(ctx->xdplua->lock);
+	ctx->xdplua = NULL;
+	return 0;
+}
+
+static const struct bpf_func_proto bpf_lua_removestate_proto = {
+	.func		= bpf_lua_removestate,
+	.gpl_only	= false,
+	.pkt_access	= false,
+	.ret_type	= RET_VOID,
+	.arg1_type	= ARG_PTR_TO_CTX,
+};
 #endif /* CONFIG_XDP_LUA */
 
 bool bpf_helper_changes_pkt_data(void *func)
@@ -6162,12 +6169,14 @@ bpf_base_func_proto(enum bpf_func_id func_id)
 		return &bpf_lua_pushskb_proto;
 	case BPF_FUNC_lua_pushstring:
 		return &bpf_lua_pushstring_proto;
-	case BPF_FUNC_lua_setstate:
-		return &bpf_lua_setstate_proto;
 	case BPF_FUNC_lua_toboolean:
 		return &bpf_lua_toboolean_proto;
 	case BPF_FUNC_lua_tointeger:
 		return &bpf_lua_tointeger_proto;
+	case BPF_FUNC_lua_putstate:
+		return &bpf_lua_putstate_proto;
+	case BPF_FUNC_lua_removestate:
+		return &bpf_lua_removestate_proto;
 #endif /* CONFIG_XDP_LUA */
 	default:
 		return NULL;

samples/bpf/xdplua_map_kern.c

@@ -27,12 +27,13 @@ int xdp_lua_test_map_prog(struct xdp_md *ctx)
 	char lookupname[] = "lookup";
 	char updatename[] = "update";
 
-	bpf_lua_setstate(ctx);
+	bpf_lua_putstate(ctx);
 	bpf_lua_pushmap(ctx, &test_map);
 	bpf_lua_pcall(ctx, updatename, 1, 0);
 
 	bpf_lua_pushmap(ctx, &test_map);
 	bpf_lua_pcall(ctx, lookupname, 1, 0);
+	bpf_lua_removestate(ctx);
 
 	return XDP_PASS;
 }

tools/include/uapi/linux/bpf.h

@@ -2836,9 +2836,10 @@ union bpf_attr {
 	FN(lua_pushmap),		\
 	FN(lua_pushskb),		\
 	FN(lua_pushstring),		\
-	FN(lua_setstate),		\
 	FN(lua_toboolean),		\
-	FN(lua_tointeger),
+	FN(lua_tointeger),		\
+	FN(lua_putstate),		\
+	FN(lua_removestate),
 	/* #endif CONFIG_XDPLUA */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper