atm: add owner of push() callback to atmvcc

The atm is using atmvcc->push(vcc, NULL) callback to notify protocol
that vcc will be closed and protocol must detach from it. This callback
is usually used by protocol to decrement module usage count by module_put(),
but it leaves small window then module is still used after module_put().

Now the owner of push() callback is kept in atmvcc and
module_put(atmvcc->owner) is called after the protocol is detached from vcc.

Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Acked-by: Chas Williams <chas@cmf.nrl.navy.mil>

diff --git a/include/linux/atmdev.h b/include/linux/atmdev.h
index 22ef21c33d0c600f5adf48d34e5bdde4687d76c4..72db2af902a8d74bb49157cd9590d9d375b82884 100644 (file)
--- a/include/linux/atmdev.h
+++ b/include/linux/atmdev.h
@@ -106,6 +106,7 @@ struct atm_vcc {
        void            *dev_data;      /* per-device data */
        void            *proto_data;    /* per-protocol data */
        struct k_atm_aal_stats *stats;  /* pointer to AAL stats group */
+       struct module *owner;           /* owner of ->push function */
        /* SVC part --- may move later ------------------------------------- */
        short           itf;            /* interface number */
        struct sockaddr_atmsvc local;

diff --git a/net/atm/common.c b/net/atm/common.c
index 0c0ad930a632f23e4c0661a20684c5d572e3dc15..24216642d6962e1483904d6a9514332f0c4ac489 100644 (file)
--- a/net/atm/common.c
+++ b/net/atm/common.c
@@ -156,6 +156,7 @@ int vcc_create(struct net *net, struct socket *sock, int protocol, int family)
        atomic_set(&sk->sk_rmem_alloc, 0);
        vcc->push = NULL;
        vcc->pop = NULL;
+       vcc->owner = NULL;
        vcc->push_oam = NULL;
        vcc->vpi = vcc->vci = 0; /* no VCI/VPI yet */
        vcc->atm_options = vcc->aal_options = 0;
@@ -175,6 +176,7 @@ static void vcc_destroy_socket(struct sock *sk)
                        vcc->dev->ops->close(vcc);
                if (vcc->push)
                        vcc->push(vcc, NULL); /* atmarpd has no push */
+               module_put(vcc->owner);
 
                while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
                        atm_return(vcc, skb->truesize);