net: sock_def_readable() and friends RCU conversion
sk_callback_lock rwlock actually protects sk->sk_sleep pointer, so we
need two atomic operations (and associated dirtying) per incoming
packet.
RCU conversion is pretty much needed :
1) Add a new structure, called "struct socket_wq" to hold all fields
that will need rcu_read_lock() protection (currently: a
wait_queue_head_t and a struct fasync_struct pointer).
[Future patch will add a list anchor for wakeup coalescing]
2) Attach one of such structure to each "struct socket" created in
sock_alloc_inode().
3) Respect RCU grace period when freeing a "struct socket_wq"
4) Change sk_sleep pointer in "struct sock" by sk_wq, pointer to "struct
socket_wq"
5) Change sk_sleep() function to use new sk->sk_wq instead of
sk->sk_sleep
6) Change sk_has_sleeper() to wq_has_sleeper() that must be used inside
a rcu_read_lock() section.
7) Change all sk_has_sleeper() callers to :
- Use rcu_read_lock() instead of read_lock(&sk->sk_callback_lock)
- Use wq_has_sleeper() to eventually wakeup tasks.
- Use rcu_read_unlock() instead of read_unlock(&sk->sk_callback_lock)
8) sock_wake_async() is modified to use rcu protection as well.
9) Exceptions :
macvtap, drivers/net/tun.c, af_unix use integrated "struct socket_wq"
instead of dynamically allocated ones. They dont need rcu freeing.
Some cleanups or followups are probably needed, (possible
sk_callback_lock conversion to a spinlock for example...).
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index 1614d78..20725e2 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -30,7 +30,7 @@
#endif
};
-#define UNIXCB(skb) (*(struct unix_skb_parms*)&((skb)->cb))
+#define UNIXCB(skb) (*(struct unix_skb_parms *)&((skb)->cb))
#define UNIXCREDS(skb) (&UNIXCB((skb)).creds)
#define UNIXSID(skb) (&UNIXCB((skb)).secid)
@@ -45,21 +45,23 @@
struct unix_sock {
/* WARNING: sk has to be the first member */
struct sock sk;
- struct unix_address *addr;
- struct dentry *dentry;
- struct vfsmount *mnt;
+ struct unix_address *addr;
+ struct dentry *dentry;
+ struct vfsmount *mnt;
struct mutex readlock;
- struct sock *peer;
- struct sock *other;
+ struct sock *peer;
+ struct sock *other;
struct list_head link;
- atomic_long_t inflight;
- spinlock_t lock;
+ atomic_long_t inflight;
+ spinlock_t lock;
unsigned int gc_candidate : 1;
unsigned int gc_maybe_cycle : 1;
- wait_queue_head_t peer_wait;
+ struct socket_wq peer_wq;
};
#define unix_sk(__sk) ((struct unix_sock *)__sk)
+#define peer_wait peer_wq.wait
+
#ifdef CONFIG_SYSCTL
extern int unix_sysctl_register(struct net *net);
extern void unix_sysctl_unregister(struct net *net);