[RFC PATCH net 2/2] [BUGFIX] bonding: use flush_delayed_work_sync inbond_close

From: Mitsuo Hayasaka
Date: Fri Oct 07 2011 - 08:44:50 EST

The bond_close() calls cancel_delayed_work() to cancel delayed works.
It, however, cannot cancel works that were already queued in workqueue.
The bond_open() initializes work->data, and proccess_one_work() refers
get_work_cwq(work)->wq->flags. The get_work_cwq() returns NULL when
work->data has been initialized. Thus, a panic occurs.

This patch uses flush_delayed_work_sync() instead of cancel_delayed_work()
in bond_close(). It cancels delayed timer and waits for work to finish
execution. So, it can avoid the null pointer dereference due to the
parallel executions of proccess_one_work() and initializing proccess
of bond_open().

Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@xxxxxxxxxxx>
Cc: Jay Vosburgh <fubar@xxxxxxxxxx>
Cc: Andy Gospodarek <andy@xxxxxxxxxxxxx>

drivers/net/bonding/bond_main.c | 10 +++++-----
1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index f1baec5..cd490b7 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3504,27 +3504,27 @@ static int bond_close(struct net_device *bond_dev)

if (bond->params.miimon) { /* link check interval, in milliseconds. */
- cancel_delayed_work(&bond->mii_work);
+ flush_delayed_work_sync(&bond->mii_work);

if (bond->params.arp_interval) { /* arp interval, in milliseconds. */
- cancel_delayed_work(&bond->arp_work);
+ flush_delayed_work_sync(&bond->arp_work);

switch (bond->params.mode) {
case BOND_MODE_8023AD:
- cancel_delayed_work(&bond->ad_work);
+ flush_delayed_work_sync(&bond->ad_work);
- cancel_delayed_work(&bond->alb_work);
+ flush_delayed_work_sync(&bond->alb_work);

if (delayed_work_pending(&bond->mcast_work))
- cancel_delayed_work(&bond->mcast_work);
+ flush_delayed_work_sync(&bond->mcast_work);

if (bond_is_lb(bond)) {
/* Must be called only after all

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