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Subject[PATCH 2/18] iseries_veth: Remove a FIXME WRT deletion of the ack_timer
Date
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>
---
drivers/net/iseries_veth.c | 21 +++++++++++++--------
1 files changed, 13 insertions(+), 8 deletions(-)
Index: veth-dev2/drivers/net/iseries_veth.c
===================================================================
--- veth-dev2.orig/drivers/net/iseries_veth.c
+++ veth-dev2/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,
-
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