[PATCH] iseries_veth: Remove a FIXME WRT deletion of the ack_timer

The iseries_veth driver has a timer which we use to send acks. When the
connection is reset or stopped we need to delete the timer.

Currently we only call del_timer() when resetting a connection, which means
the timer might run again while the connection is being re-setup. As it turns
out that's ok, because the flags the timer consults have been reset.

It's cleaner though to call del_timer_sync() once we've dropped the lock,
although the timer may still run between us dropping the lock and calling
del_timer_sync(), but as above that's ok.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

1 files changed, 13 insertions, 8 deletions

diff --git a/drivers/net/iseries_veth.c b/drivers/net/iseries_veth.c
index d5b08dc8a9f8..c19b32e0a5ad 100644
--- a/drivers/net/iseries_veth.c
+++ b/drivers/net/iseries_veth.c
@@ -450,13 +450,15 @@ static void veth_statemachine(void *p)
         if (cnx->state & VETH_STATE_RESET) {
                 int i;
 
-                del_timer(&cnx->ack_timer);
-
                 if (cnx->state & VETH_STATE_OPEN)
                         HvCallEvent_closeLpEventPath(cnx->remote_lp,
                                                      HvLpEvent_Type_VirtualLan);
 
-                /* reset ack data */
+                /*
+                 * Reset ack data. This prevents the ack_timer actually
+                 * doing anything, even if it runs one more time when
+                 * we drop the lock below.
+                 */
                 memset(&cnx->pending_acks, 0xff, sizeof (cnx->pending_acks));
                 cnx->num_pending_acks = 0;
 
@@ -469,9 +471,16 @@ static void veth_statemachine(void *p)
                 if (cnx->msgs)
                         for (i = 0; i < VETH_NUMBUFFERS; ++i)
                                 veth_recycle_msg(cnx, cnx->msgs + i);
+
+                /* Drop the lock so we can do stuff that might sleep or
+                 * take other locks. */
                 spin_unlock_irq(&cnx->lock);
+
+                del_timer_sync(&cnx->ack_timer);
                 veth_flush_pending(cnx);
+
                 spin_lock_irq(&cnx->lock);
+
                 if (cnx->state & VETH_STATE_RESET)
                         goto restart;
         }
@@ -658,13 +667,9 @@ static void veth_stop_connection(u8 rlp)
         veth_kick_statemachine(cnx);
         spin_unlock_irq(&cnx->lock);
 
+        /* Wait for the state machine to run. */
         flush_scheduled_work();
 
-        /* FIXME: not sure if this is necessary - will already have
-         * been deleted by the state machine, just want to make sure
-         * its not running any more */
-        del_timer_sync(&cnx->ack_timer);
-
         if (cnx->num_events > 0)
                 mf_deallocate_lp_events(cnx->remote_lp,
                                       HvLpEvent_Type_VirtualLan,