Merge tag 'for-v3.8-part2' of git://git.infradead.org/battery-2.6

[karo-tx-linux.git] / net / atm / pppoatm.c

diff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c
index c4a57bca77bf6b171a57d25401a69227b73662a1..8c93267ce96910a48f9eb9e5bb8e295470656edf 100644 (file)
--- a/net/atm/pppoatm.c
+++ b/net/atm/pppoatm.c
@@ -60,6 +60,7 @@ struct pppoatm_vcc {
        struct atm_vcc  *atmvcc;        /* VCC descriptor */
        void (*old_push)(struct atm_vcc *, struct sk_buff *);
        void (*old_pop)(struct atm_vcc *, struct sk_buff *);
+       void (*old_release_cb)(struct atm_vcc *);
        struct module *old_owner;
                                        /* keep old push/pop for detaching */
        enum pppoatm_encaps encaps;
@@ -108,6 +109,24 @@ static void pppoatm_wakeup_sender(unsigned long arg)
        ppp_output_wakeup((struct ppp_channel *) arg);
 }
 
+static void pppoatm_release_cb(struct atm_vcc *atmvcc)
+{
+       struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
+
+       /*
+        * As in pppoatm_pop(), it's safe to clear the BLOCKED bit here because
+        * the wakeup *can't* race with pppoatm_send(). They both hold the PPP
+        * channel's ->downl lock. And the potential race with *setting* it,
+        * which leads to the double-check dance in pppoatm_may_send(), doesn't
+        * exist here. In the sock_owned_by_user() case in pppoatm_send(), we
+        * set the BLOCKED bit while the socket is still locked. We know that
+        * ->release_cb() can't be called until that's done.
+        */
+       if (test_and_clear_bit(BLOCKED, &pvcc->blocked))
+               tasklet_schedule(&pvcc->wakeup_tasklet);
+       if (pvcc->old_release_cb)
+               pvcc->old_release_cb(atmvcc);
+}
 /*
  * This gets called every time the ATM card has finished sending our
  * skb.  The ->old_pop will take care up normal atm flow control,
@@ -152,6 +171,7 @@ static void pppoatm_unassign_vcc(struct atm_vcc *atmvcc)
        pvcc = atmvcc_to_pvcc(atmvcc);
        atmvcc->push = pvcc->old_push;
        atmvcc->pop = pvcc->old_pop;
+       atmvcc->release_cb = pvcc->old_release_cb;
        tasklet_kill(&pvcc->wakeup_tasklet);
        ppp_unregister_channel(&pvcc->chan);
        atmvcc->user_back = NULL;
@@ -214,7 +234,7 @@ error:
        ppp_input_error(&pvcc->chan, 0);
 }
 
-static inline int pppoatm_may_send(struct pppoatm_vcc *pvcc, int size)
+static int pppoatm_may_send(struct pppoatm_vcc *pvcc, int size)
 {
        /*
         * It's not clear that we need to bother with using atm_may_send()
@@ -282,8 +302,22 @@ static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb)
 
        vcc = ATM_SKB(skb)->vcc;
        bh_lock_sock(sk_atm(vcc));
-       if (sock_owned_by_user(sk_atm(vcc)))
+       if (sock_owned_by_user(sk_atm(vcc))) {
+               /*
+                * Needs to happen (and be flushed, hence test_and_) before we unlock
+                * the socket. It needs to be seen by the time our ->release_cb gets
+                * called.
+                */
+               test_and_set_bit(BLOCKED, &pvcc->blocked);
                goto nospace;
+       }
+       if (test_bit(ATM_VF_RELEASED, &vcc->flags) ||
+           test_bit(ATM_VF_CLOSE, &vcc->flags) ||
+           !test_bit(ATM_VF_READY, &vcc->flags)) {
+               bh_unlock_sock(sk_atm(vcc));
+               kfree_skb(skb);
+               return DROP_PACKET;
+       }
 
        switch (pvcc->encaps) {         /* LLC encapsulation needed */
        case e_llc:
@@ -381,6 +415,7 @@ static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg)
        pvcc->old_push = atmvcc->push;
        pvcc->old_pop = atmvcc->pop;
        pvcc->old_owner = atmvcc->owner;
+       pvcc->old_release_cb = atmvcc->release_cb;
        pvcc->encaps = (enum pppoatm_encaps) be.encaps;
        pvcc->chan.private = pvcc;
        pvcc->chan.ops = &pppoatm_ops;
@@ -396,6 +431,7 @@ static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg)
        atmvcc->user_back = pvcc;
        atmvcc->push = pppoatm_push;
        atmvcc->pop = pppoatm_pop;
+       atmvcc->release_cb = pppoatm_release_cb;
        __module_get(THIS_MODULE);
        atmvcc->owner = THIS_MODULE;