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-rw-r--r--fs/fcntl.c66
-rw-r--r--include/linux/fs.h12
-rw-r--r--net/socket.c73
3 files changed, 59 insertions, 92 deletions
diff --git a/fs/fcntl.c b/fs/fcntl.c
index 452d02f9075..0a140741b39 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -614,9 +614,15 @@ int send_sigurg(struct fown_struct *fown)
return ret;
}
-static DEFINE_RWLOCK(fasync_lock);
+static DEFINE_SPINLOCK(fasync_lock);
static struct kmem_cache *fasync_cache __read_mostly;
+static void fasync_free_rcu(struct rcu_head *head)
+{
+ kmem_cache_free(fasync_cache,
+ container_of(head, struct fasync_struct, fa_rcu));
+}
+
/*
* Remove a fasync entry. If successfully removed, return
* positive and clear the FASYNC flag. If no entry exists,
@@ -625,8 +631,6 @@ static struct kmem_cache *fasync_cache __read_mostly;
* NOTE! It is very important that the FASYNC flag always
* match the state "is the filp on a fasync list".
*
- * We always take the 'filp->f_lock', in since fasync_lock
- * needs to be irq-safe.
*/
static int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
{
@@ -634,17 +638,22 @@ static int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
int result = 0;
spin_lock(&filp->f_lock);
- write_lock_irq(&fasync_lock);
+ spin_lock(&fasync_lock);
for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
if (fa->fa_file != filp)
continue;
+
+ spin_lock_irq(&fa->fa_lock);
+ fa->fa_file = NULL;
+ spin_unlock_irq(&fa->fa_lock);
+
*fp = fa->fa_next;
- kmem_cache_free(fasync_cache, fa);
+ call_rcu(&fa->fa_rcu, fasync_free_rcu);
filp->f_flags &= ~FASYNC;
result = 1;
break;
}
- write_unlock_irq(&fasync_lock);
+ spin_unlock(&fasync_lock);
spin_unlock(&filp->f_lock);
return result;
}
@@ -666,25 +675,30 @@ static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fa
return -ENOMEM;
spin_lock(&filp->f_lock);
- write_lock_irq(&fasync_lock);
+ spin_lock(&fasync_lock);
for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
if (fa->fa_file != filp)
continue;
+
+ spin_lock_irq(&fa->fa_lock);
fa->fa_fd = fd;
+ spin_unlock_irq(&fa->fa_lock);
+
kmem_cache_free(fasync_cache, new);
goto out;
}
+ spin_lock_init(&new->fa_lock);
new->magic = FASYNC_MAGIC;
new->fa_file = filp;
new->fa_fd = fd;
new->fa_next = *fapp;
- *fapp = new;
+ rcu_assign_pointer(*fapp, new);
result = 1;
filp->f_flags |= FASYNC;
out:
- write_unlock_irq(&fasync_lock);
+ spin_unlock(&fasync_lock);
spin_unlock(&filp->f_lock);
return result;
}
@@ -704,37 +718,41 @@ int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fap
EXPORT_SYMBOL(fasync_helper);
-void __kill_fasync(struct fasync_struct *fa, int sig, int band)
+/*
+ * rcu_read_lock() is held
+ */
+static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
{
while (fa) {
- struct fown_struct * fown;
+ struct fown_struct *fown;
if (fa->magic != FASYNC_MAGIC) {
printk(KERN_ERR "kill_fasync: bad magic number in "
"fasync_struct!\n");
return;
}
- fown = &fa->fa_file->f_owner;
- /* Don't send SIGURG to processes which have not set a
- queued signum: SIGURG has its own default signalling
- mechanism. */
- if (!(sig == SIGURG && fown->signum == 0))
- send_sigio(fown, fa->fa_fd, band);
- fa = fa->fa_next;
+ spin_lock(&fa->fa_lock);
+ if (fa->fa_file) {
+ fown = &fa->fa_file->f_owner;
+ /* Don't send SIGURG to processes which have not set a
+ queued signum: SIGURG has its own default signalling
+ mechanism. */
+ if (!(sig == SIGURG && fown->signum == 0))
+ send_sigio(fown, fa->fa_fd, band);
+ }
+ spin_unlock(&fa->fa_lock);
+ fa = rcu_dereference(fa->fa_next);
}
}
-EXPORT_SYMBOL(__kill_fasync);
-
void kill_fasync(struct fasync_struct **fp, int sig, int band)
{
/* First a quick test without locking: usually
* the list is empty.
*/
if (*fp) {
- read_lock(&fasync_lock);
- /* reread *fp after obtaining the lock */
- __kill_fasync(*fp, sig, band);
- read_unlock(&fasync_lock);
+ rcu_read_lock();
+ kill_fasync_rcu(rcu_dereference(*fp), sig, band);
+ rcu_read_unlock();
}
}
EXPORT_SYMBOL(kill_fasync);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 39d57bc6cc7..018d382f6f9 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1280,10 +1280,12 @@ static inline int lock_may_write(struct inode *inode, loff_t start,
struct fasync_struct {
- int magic;
- int fa_fd;
- struct fasync_struct *fa_next; /* singly linked list */
- struct file *fa_file;
+ spinlock_t fa_lock;
+ int magic;
+ int fa_fd;
+ struct fasync_struct *fa_next; /* singly linked list */
+ struct file *fa_file;
+ struct rcu_head fa_rcu;
};
#define FASYNC_MAGIC 0x4601
@@ -1292,8 +1294,6 @@ struct fasync_struct {
extern int fasync_helper(int, struct file *, int, struct fasync_struct **);
/* can be called from interrupts */
extern void kill_fasync(struct fasync_struct **, int, int);
-/* only for net: no internal synchronization */
-extern void __kill_fasync(struct fasync_struct *, int, int);
extern int __f_setown(struct file *filp, struct pid *, enum pid_type, int force);
extern int f_setown(struct file *filp, unsigned long arg, int force);
diff --git a/net/socket.c b/net/socket.c
index 35bc198bbf6..9822081eab3 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1067,78 +1067,27 @@ static int sock_close(struct inode *inode, struct file *filp)
* 1. fasync_list is modified only under process context socket lock
* i.e. under semaphore.
* 2. fasync_list is used under read_lock(&sk->sk_callback_lock)
- * or under socket lock.
- * 3. fasync_list can be used from softirq context, so that
- * modification under socket lock have to be enhanced with
- * write_lock_bh(&sk->sk_callback_lock).
- * --ANK (990710)
+ * or under socket lock
*/
static int sock_fasync(int fd, struct file *filp, int on)
{
- struct fasync_struct *fa, *fna = NULL, **prev;
- struct socket *sock;
- struct sock *sk;
-
- if (on) {
- fna = kmalloc(sizeof(struct fasync_struct), GFP_KERNEL);
- if (fna == NULL)
- return -ENOMEM;
- }
-
- sock = filp->private_data;
+ struct socket *sock = filp->private_data;
+ struct sock *sk = sock->sk;
- sk = sock->sk;
- if (sk == NULL) {
- kfree(fna);
+ if (sk == NULL)
return -EINVAL;
- }
lock_sock(sk);
- spin_lock(&filp->f_lock);
- if (on)
- filp->f_flags |= FASYNC;
- else
- filp->f_flags &= ~FASYNC;
- spin_unlock(&filp->f_lock);
-
- prev = &(sock->fasync_list);
+ fasync_helper(fd, filp, on, &sock->fasync_list);
- for (fa = *prev; fa != NULL; prev = &fa->fa_next, fa = *prev)
- if (fa->fa_file == filp)
- break;
-
- if (on) {
- if (fa != NULL) {
- write_lock_bh(&sk->sk_callback_lock);
- fa->fa_fd = fd;
- write_unlock_bh(&sk->sk_callback_lock);
-
- kfree(fna);
- goto out;
- }
- fna->fa_file = filp;
- fna->fa_fd = fd;
- fna->magic = FASYNC_MAGIC;
- fna->fa_next = sock->fasync_list;
- write_lock_bh(&sk->sk_callback_lock);
- sock->fasync_list = fna;
+ if (!sock->fasync_list)
+ sock_reset_flag(sk, SOCK_FASYNC);
+ else
sock_set_flag(sk, SOCK_FASYNC);
- write_unlock_bh(&sk->sk_callback_lock);
- } else {
- if (fa != NULL) {
- write_lock_bh(&sk->sk_callback_lock);
- *prev = fa->fa_next;
- if (!sock->fasync_list)
- sock_reset_flag(sk, SOCK_FASYNC);
- write_unlock_bh(&sk->sk_callback_lock);
- kfree(fa);
- }
- }
-out:
- release_sock(sock->sk);
+ release_sock(sk);
return 0;
}
@@ -1159,10 +1108,10 @@ int sock_wake_async(struct socket *sock, int how, int band)
/* fall through */
case SOCK_WAKE_IO:
call_kill:
- __kill_fasync(sock->fasync_list, SIGIO, band);
+ kill_fasync(&sock->fasync_list, SIGIO, band);
break;
case SOCK_WAKE_URG:
- __kill_fasync(sock->fasync_list, SIGURG, band);
+ kill_fasync(&sock->fasync_list, SIGURG, band);
}
return 0;
}
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2024-11-25 23:45:52 +0000