Merge branch 'netpoll-make-sure-napi_list-is-safe-for-RCU-traversal'

Jakub Kicinski says:

====================
netpoll: make sure napi_list is safe for RCU traversal

This series is a follow-up to the fix in commit 96e97bc07e90 ("net:
disable netpoll on fresh napis"). To avoid any latent race conditions
convert dev->napi_list to a proper RCU list. We need minor restructuring
because it looks like netif_napi_del() used to be idempotent, and
it may be quite hard to track down everyone who depends on that.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 18 insertions, 18 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 7f9fcfd15942..157e0242e9ee 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -70,6 +70,7 @@ struct udp_tunnel_nic;
 struct bpf_prog;
 struct xdp_buff;
 
+void synchronize_net(void);
 void netdev_set_default_ethtool_ops(struct net_device *dev,
 				    const struct ethtool_ops *ops);
 
@@ -354,7 +355,7 @@ enum {
 	NAPI_STATE_MISSED,	/* reschedule a napi */
 	NAPI_STATE_DISABLE,	/* Disable pending */
 	NAPI_STATE_NPSVC,	/* Netpoll - don't dequeue from poll_list */
-	NAPI_STATE_HASHED,	/* In NAPI hash (busy polling possible) */
+	NAPI_STATE_LISTED,	/* NAPI added to system lists */
 	NAPI_STATE_NO_BUSY_POLL,/* Do not add in napi_hash, no busy polling */
 	NAPI_STATE_IN_BUSY_POLL,/* sk_busy_loop() owns this NAPI */
 };
@@ -364,7 +365,7 @@ enum {
 	NAPIF_STATE_MISSED	 = BIT(NAPI_STATE_MISSED),
 	NAPIF_STATE_DISABLE	 = BIT(NAPI_STATE_DISABLE),
 	NAPIF_STATE_NPSVC	 = BIT(NAPI_STATE_NPSVC),
-	NAPIF_STATE_HASHED	 = BIT(NAPI_STATE_HASHED),
+	NAPIF_STATE_LISTED	 = BIT(NAPI_STATE_LISTED),
 	NAPIF_STATE_NO_BUSY_POLL = BIT(NAPI_STATE_NO_BUSY_POLL),
 	NAPIF_STATE_IN_BUSY_POLL = BIT(NAPI_STATE_IN_BUSY_POLL),
 };
@@ -489,20 +490,6 @@ static inline bool napi_complete(struct napi_struct *n)
 }
 
 /**
- *	napi_hash_del - remove a NAPI from global table
- *	@napi: NAPI context
- *
- * Warning: caller must observe RCU grace period
- * before freeing memory containing @napi, if
- * this function returns true.
- * Note: core networking stack automatically calls it
- * from netif_napi_del().
- * Drivers might want to call this helper to combine all
- * the needed RCU grace periods into a single one.
- */
-bool napi_hash_del(struct napi_struct *napi);
-
-/**
  *	napi_disable - prevent NAPI from scheduling
  *	@n: NAPI context
  *
@@ -2368,12 +2355,26 @@ static inline void netif_tx_napi_add(struct net_device *dev,
 }
 
 /**
+ *  __netif_napi_del - remove a NAPI context
+ *  @napi: NAPI context
+ *
+ * Warning: caller must observe RCU grace period before freeing memory
+ * containing @napi. Drivers might want to call this helper to combine
+ * all the needed RCU grace periods into a single one.
+ */
+void __netif_napi_del(struct napi_struct *napi);
+
+/**
  *  netif_napi_del - remove a NAPI context
  *  @napi: NAPI context
  *
  *  netif_napi_del() removes a NAPI context from the network device NAPI list
  */
-void netif_napi_del(struct napi_struct *napi);
+static inline void netif_napi_del(struct napi_struct *napi)
+{
+	__netif_napi_del(napi);
+	synchronize_net();
+}
 
 struct napi_gro_cb {
 	/* Virtual address of skb_shinfo(skb)->frags[0].page + offset. */
@@ -2797,7 +2798,6 @@ static inline void unregister_netdevice(struct net_device *dev)
 int netdev_refcnt_read(const struct net_device *dev);
 void free_netdev(struct net_device *dev);
 void netdev_freemem(struct net_device *dev);
-void synchronize_net(void);
 int init_dummy_netdev(struct net_device *dev);
 
 struct net_device *netdev_get_xmit_slave(struct net_device *dev,