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Message-ID: <20240208141154.1131622-5-edumazet@google.com>
Date: Thu, 8 Feb 2024 14:11:45 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com,
Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH v2 net-next 04/13] net: convert dev->reg_state to standard enum
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.
v2: use a standard enum, so that try_cmpxchg() added
in a followup patch will work on all arches.
( https://lore.kernel.org/oe-kbuild-all/202402081918.OLyGaea3-lkp@intel.com/ )
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
include/linux/netdevice.h | 25 +++++++++++++++----------
net/core/dev.c | 8 ++++----
2 files changed, 19 insertions(+), 14 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 07cefa32eafa93dd1a4602de892d0ee1cbf2e22b..5f138025d5f189cd5ab7bb0434205b66d30e60e7 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.
*
@@ -2372,22 +2381,16 @@ 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;
+ enum netdev_reg_state reg_state;
bool dismantle;
+ bool needs_free_netdev;
enum {
RTNL_LINK_INITIALIZED,
RTNL_LINK_INITIALIZING,
} rtnl_link_state:16;
- bool needs_free_netdev;
void (*priv_destructor)(struct net_device *dev);
/* mid-layer private */
@@ -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) {
+ enum netdev_reg_state 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 c0db7408fa9f9a3ae9b5b83d34b50663604a5f99..89dbba691c9db83102d15074b6ea96312689be10 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10268,7 +10268,7 @@ 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;
@@ -10559,7 +10559,7 @@ 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);
}
@@ -10979,7 +10979,7 @@ 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);
@@ -11069,7 +11069,7 @@ 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();
--
2.43.0.594.gd9cf4e227d-goog
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