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authorEric Dumazet <eric.dumazet@gmail.com>2010-04-29 11:01:49 +0000
committerDavid S. Miller <davem@davemloft.net>2010-05-01 15:00:15 -0700
commit43815482370c510c569fd18edb57afcb0fa8cab6 (patch)
tree063efaae3758402b84f056438b704d1de68f7837 /include/linux
parent83d7eb2979cd3390c375470225dd2d8f2009bc70 (diff)
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>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/net.h14
1 files changed, 9 insertions, 5 deletions
diff --git a/include/linux/net.h b/include/linux/net.h
index 4157b5d42bd6..2b4deeeb8646 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -59,6 +59,7 @@ typedef enum {
#include <linux/wait.h>
#include <linux/fcntl.h> /* For O_CLOEXEC and O_NONBLOCK */
#include <linux/kmemcheck.h>
+#include <linux/rcupdate.h>
struct poll_table_struct;
struct pipe_inode_info;
@@ -116,6 +117,12 @@ enum sock_shutdown_cmd {
SHUT_RDWR = 2,
};
+struct socket_wq {
+ wait_queue_head_t wait;
+ struct fasync_struct *fasync_list;
+ struct rcu_head rcu;
+} ____cacheline_aligned_in_smp;
+
/**
* struct socket - general BSD socket
* @state: socket state (%SS_CONNECTED, etc)
@@ -135,11 +142,8 @@ struct socket {
kmemcheck_bitfield_end(type);
unsigned long flags;
- /*
- * Please keep fasync_list & wait fields in the same cache line
- */
- struct fasync_struct *fasync_list;
- wait_queue_head_t wait;
+
+ struct socket_wq *wq;
struct file *file;
struct sock *sk;