usb: gadget: phonet: Add Phonet over ACM for RMC
[linux-3.10.git] / net / unix / garbage.c
index 399717e..9bc73f8 100644 (file)
 #include <linux/un.h>
 #include <linux/net.h>
 #include <linux/fs.h>
-#include <linux/slab.h>
 #include <linux/skbuff.h>
 #include <linux/netdevice.h>
 #include <linux/file.h>
 #include <linux/proc_fs.h>
 #include <linux/mutex.h>
+#include <linux/wait.h>
 
 #include <net/sock.h>
 #include <net/af_unix.h>
 static LIST_HEAD(gc_inflight_list);
 static LIST_HEAD(gc_candidates);
 static DEFINE_SPINLOCK(unix_gc_lock);
+static DECLARE_WAIT_QUEUE_HEAD(unix_gc_wait);
 
 unsigned int unix_tot_inflight;
 
 
-static struct sock *unix_get_socket(struct file *filp)
+struct sock *unix_get_socket(struct file *filp)
 {
        struct sock *u_sock = NULL;
-       struct inode *inode = filp->f_path.dentry->d_inode;
+       struct inode *inode = file_inode(filp);
 
        /*
         *      Socket ?
         */
-       if (S_ISSOCK(inode->i_mode)) {
-               struct socket * sock = SOCKET_I(inode);
-               struct sock * s = sock->sk;
+       if (S_ISSOCK(inode->i_mode) && !(filp->f_mode & FMODE_PATH)) {
+               struct socket *sock = SOCKET_I(inode);
+               struct sock *s = sock->sk;
 
                /*
                 *      PF_UNIX ?
@@ -124,10 +125,10 @@ static struct sock *unix_get_socket(struct file *filp)
 void unix_inflight(struct file *fp)
 {
        struct sock *s = unix_get_socket(fp);
-       if(s) {
+       if (s) {
                struct unix_sock *u = unix_sk(s);
                spin_lock(&unix_gc_lock);
-               if (atomic_inc_return(&u->inflight) == 1) {
+               if (atomic_long_inc_return(&u->inflight) == 1) {
                        BUG_ON(!list_empty(&u->link));
                        list_add_tail(&u->link, &gc_inflight_list);
                } else {
@@ -141,34 +142,25 @@ void unix_inflight(struct file *fp)
 void unix_notinflight(struct file *fp)
 {
        struct sock *s = unix_get_socket(fp);
-       if(s) {
+       if (s) {
                struct unix_sock *u = unix_sk(s);
                spin_lock(&unix_gc_lock);
                BUG_ON(list_empty(&u->link));
-               if (atomic_dec_and_test(&u->inflight))
+               if (atomic_long_dec_and_test(&u->inflight))
                        list_del_init(&u->link);
                unix_tot_inflight--;
                spin_unlock(&unix_gc_lock);
        }
 }
 
-static inline struct sk_buff *sock_queue_head(struct sock *sk)
-{
-       return (struct sk_buff *) &sk->sk_receive_queue;
-}
-
-#define receive_queue_for_each_skb(sk, next, skb) \
-       for (skb = sock_queue_head(sk)->next, next = skb->next; \
-            skb != sock_queue_head(sk); skb = next, next = skb->next)
-
-static void scan_inflight(struct sock *x, void (*func)(struct sock *),
+static void scan_inflight(struct sock *x, void (*func)(struct unix_sock *),
                          struct sk_buff_head *hitlist)
 {
        struct sk_buff *skb;
        struct sk_buff *next;
 
        spin_lock(&x->sk_receive_queue.lock);
-       receive_queue_for_each_skb(x, next, skb) {
+       skb_queue_walk_safe(&x->sk_receive_queue, skb, next) {
                /*
                 *      Do we have file descriptors ?
                 */
@@ -185,9 +177,18 @@ static void scan_inflight(struct sock *x, void (*func)(struct sock *),
                                 *      if it indeed does so
                                 */
                                struct sock *sk = unix_get_socket(*fp++);
-                               if(sk) {
-                                       hit = true;
-                                       func(sk);
+                               if (sk) {
+                                       struct unix_sock *u = unix_sk(sk);
+
+                                       /*
+                                        * Ignore non-candidates, they could
+                                        * have been added to the queues after
+                                        * starting the garbage collection
+                                        */
+                                       if (test_bit(UNIX_GC_CANDIDATE, &u->gc_flags)) {
+                                               hit = true;
+                                               func(u);
+                                       }
                                }
                        }
                        if (hit && hitlist != NULL) {
@@ -199,7 +200,7 @@ static void scan_inflight(struct sock *x, void (*func)(struct sock *),
        spin_unlock(&x->sk_receive_queue.lock);
 }
 
-static void scan_children(struct sock *x, void (*func)(struct sock *),
+static void scan_children(struct sock *x, void (*func)(struct unix_sock *),
                          struct sk_buff_head *hitlist)
 {
        if (x->sk_state != TCP_LISTEN)
@@ -215,7 +216,7 @@ static void scan_children(struct sock *x, void (*func)(struct sock *),
                 * and perform a scan on them as well.
                 */
                spin_lock(&x->sk_receive_queue.lock);
-               receive_queue_for_each_skb(x, next, skb) {
+               skb_queue_walk_safe(&x->sk_receive_queue, skb, next) {
                        u = unix_sk(skb->sk);
 
                        /*
@@ -235,40 +236,50 @@ static void scan_children(struct sock *x, void (*func)(struct sock *),
        }
 }
 
-static void dec_inflight(struct sock *sk)
+static void dec_inflight(struct unix_sock *usk)
 {
-       atomic_dec(&unix_sk(sk)->inflight);
+       atomic_long_dec(&usk->inflight);
 }
 
-static void inc_inflight(struct sock *sk)
+static void inc_inflight(struct unix_sock *usk)
 {
-       atomic_inc(&unix_sk(sk)->inflight);
+       atomic_long_inc(&usk->inflight);
 }
 
-static void inc_inflight_move_tail(struct sock *sk)
+static void inc_inflight_move_tail(struct unix_sock *u)
 {
-       struct unix_sock *u = unix_sk(sk);
-
-       atomic_inc(&u->inflight);
+       atomic_long_inc(&u->inflight);
        /*
-        * If this is still a candidate, move it to the end of the
-        * list, so that it's checked even if it was already passed
-        * over
+        * If this still might be part of a cycle, move it to the end
+        * of the list, so that it's checked even if it was already
+        * passed over
         */
-       if (u->gc_candidate)
+       if (test_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags))
                list_move_tail(&u->link, &gc_candidates);
 }
 
-/* The external entry point: unix_gc() */
+static bool gc_in_progress = false;
+#define UNIX_INFLIGHT_TRIGGER_GC 16000
 
-void unix_gc(void)
+void wait_for_unix_gc(void)
 {
-       static bool gc_in_progress = false;
+       /*
+        * If number of inflight sockets is insane,
+        * force a garbage collect right now.
+        */
+       if (unix_tot_inflight > UNIX_INFLIGHT_TRIGGER_GC && !gc_in_progress)
+               unix_gc();
+       wait_event(unix_gc_wait, gc_in_progress == false);
+}
 
+/* The external entry point: unix_gc() */
+void unix_gc(void)
+{
        struct unix_sock *u;
        struct unix_sock *next;
        struct sk_buff_head hitlist;
        struct list_head cursor;
+       LIST_HEAD(not_cycle_list);
 
        spin_lock(&unix_gc_lock);
 
@@ -284,23 +295,28 @@ void unix_gc(void)
         *
         * Holding unix_gc_lock will protect these candidates from
         * being detached, and hence from gaining an external
-        * reference.  This also means, that since there are no
-        * possible receivers, the receive queues of these sockets are
-        * static during the GC, even though the dequeue is done
-        * before the detach without atomicity guarantees.
+        * reference.  Since there are no possible receivers, all
+        * buffers currently on the candidates' queues stay there
+        * during the garbage collection.
+        *
+        * We also know that no new candidate can be added onto the
+        * receive queues.  Other, non candidate sockets _can_ be
+        * added to queue, so we must make sure only to touch
+        * candidates.
         */
        list_for_each_entry_safe(u, next, &gc_inflight_list, link) {
-               int total_refs;
-               int inflight_refs;
+               long total_refs;
+               long inflight_refs;
 
                total_refs = file_count(u->sk.sk_socket->file);
-               inflight_refs = atomic_read(&u->inflight);
+               inflight_refs = atomic_long_read(&u->inflight);
 
                BUG_ON(inflight_refs < 1);
                BUG_ON(total_refs < inflight_refs);
                if (total_refs == inflight_refs) {
                        list_move_tail(&u->link, &gc_candidates);
-                       u->gc_candidate = 1;
+                       __set_bit(UNIX_GC_CANDIDATE, &u->gc_flags);
+                       __set_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags);
                }
        }
 
@@ -326,22 +342,32 @@ void unix_gc(void)
                /* Move cursor to after the current position. */
                list_move(&cursor, &u->link);
 
-               if (atomic_read(&u->inflight) > 0) {
-                       list_move_tail(&u->link, &gc_inflight_list);
-                       u->gc_candidate = 0;
+               if (atomic_long_read(&u->inflight) > 0) {
+                       list_move_tail(&u->link, &not_cycle_list);
+                       __clear_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags);
                        scan_children(&u->sk, inc_inflight_move_tail, NULL);
                }
        }
        list_del(&cursor);
 
        /*
+        * not_cycle_list contains those sockets which do not make up a
+        * cycle.  Restore these to the inflight list.
+        */
+       while (!list_empty(&not_cycle_list)) {
+               u = list_entry(not_cycle_list.next, struct unix_sock, link);
+               __clear_bit(UNIX_GC_CANDIDATE, &u->gc_flags);
+               list_move_tail(&u->link, &gc_inflight_list);
+       }
+
+       /*
         * Now gc_candidates contains only garbage.  Restore original
         * inflight counters for these as well, and remove the skbuffs
         * which are creating the cycle(s).
         */
        skb_queue_head_init(&hitlist);
        list_for_each_entry(u, &gc_candidates, link)
-               scan_children(&u->sk, inc_inflight, &hitlist);
+       scan_children(&u->sk, inc_inflight, &hitlist);
 
        spin_unlock(&unix_gc_lock);
 
@@ -353,6 +379,7 @@ void unix_gc(void)
        /* All candidates should have been detached by now. */
        BUG_ON(!list_empty(&gc_candidates));
        gc_in_progress = false;
+       wake_up(&unix_gc_wait);
 
  out:
        spin_unlock(&unix_gc_lock);