From 4d42b37def70327b2bb19f823d42289aed2cd7c7 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 13 Feb 2024 06:32:36 +0000 Subject: [PATCH] net: convert dev->reg_state to u8 Prepares things so that dev->reg_state reads can be lockless, by adding WRITE_ONCE() on write side. READ_ONCE()/WRITE_ONCE() do not support bitfields. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/netdevice.h | 23 ++++++++++++++--------- net/core/dev.c | 8 ++++---- 2 files changed, 18 insertions(+), 13 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index a3f9c95da51e..631124655107 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1815,6 +1815,15 @@ enum netdev_stat_type { NETDEV_PCPU_STAT_DSTATS, /* struct pcpu_dstats */ }; +enum netdev_reg_state { + NETREG_UNINITIALIZED = 0, + NETREG_REGISTERED, /* completed register_netdevice */ + NETREG_UNREGISTERING, /* called unregister_netdevice */ + NETREG_UNREGISTERED, /* completed unregister todo */ + NETREG_RELEASED, /* called free_netdev */ + NETREG_DUMMY, /* dummy device for NAPI poll */ +}; + /** * struct net_device - The DEVICE structure. * @@ -2372,13 +2381,7 @@ struct net_device { struct list_head link_watch_list; - enum { NETREG_UNINITIALIZED=0, - NETREG_REGISTERED, /* completed register_netdevice */ - NETREG_UNREGISTERING, /* called unregister_netdevice */ - NETREG_UNREGISTERED, /* completed unregister todo */ - NETREG_RELEASED, /* called free_netdev */ - NETREG_DUMMY, /* dummy device for NAPI poll */ - } reg_state:8; + u8 reg_state; bool dismantle; @@ -5254,7 +5257,9 @@ static inline const char *netdev_name(const struct net_device *dev) static inline const char *netdev_reg_state(const struct net_device *dev) { - switch (dev->reg_state) { + u8 reg_state = READ_ONCE(dev->reg_state); + + switch (reg_state) { case NETREG_UNINITIALIZED: return " (uninitialized)"; case NETREG_REGISTERED: return ""; case NETREG_UNREGISTERING: return " (unregistering)"; @@ -5263,7 +5268,7 @@ static inline const char *netdev_reg_state(const struct net_device *dev) case NETREG_DUMMY: return " (dummy)"; } - WARN_ONCE(1, "%s: unknown reg_state %d\n", dev->name, dev->reg_state); + WARN_ONCE(1, "%s: unknown reg_state %d\n", dev->name, reg_state); return " (unknown)"; } diff --git a/net/core/dev.c b/net/core/dev.c index 720bd6838212..9c95cae9d6ab 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -10339,7 +10339,7 @@ int register_netdevice(struct net_device *dev) ret = netdev_register_kobject(dev); write_lock(&dev_base_lock); - dev->reg_state = ret ? NETREG_UNREGISTERED : NETREG_REGISTERED; + WRITE_ONCE(dev->reg_state, ret ? NETREG_UNREGISTERED : NETREG_REGISTERED); write_unlock(&dev_base_lock); if (ret) goto err_uninit_notify; @@ -10630,7 +10630,7 @@ void netdev_run_todo(void) } write_lock(&dev_base_lock); - dev->reg_state = NETREG_UNREGISTERED; + WRITE_ONCE(dev->reg_state, NETREG_UNREGISTERED); write_unlock(&dev_base_lock); linkwatch_sync_dev(dev); } @@ -11050,7 +11050,7 @@ void free_netdev(struct net_device *dev) } BUG_ON(dev->reg_state != NETREG_UNREGISTERED); - dev->reg_state = NETREG_RELEASED; + WRITE_ONCE(dev->reg_state, NETREG_RELEASED); /* will free via device release */ put_device(&dev->dev); @@ -11140,7 +11140,7 @@ void unregister_netdevice_many_notify(struct list_head *head, /* And unlink it from device chain. */ write_lock(&dev_base_lock); unlist_netdevice(dev, false); - dev->reg_state = NETREG_UNREGISTERING; + WRITE_ONCE(dev->reg_state, NETREG_UNREGISTERING); write_unlock(&dev_base_lock); } flush_all_backlogs();