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Subject[PATCH net v2 6/8] forcedeth: Fix a race during rmmod of forcedeth
Date
From: Salman Qazi <sqazi@google.com>

The race was between del_timer_sync and nv_do_stats_poll called through
nv_get_ethtool_stats. To prevent this, we have to introduce mutual
exclusion between nv_get_ethtool_stats and del_timer_sync. Notice
that we don't put the mutual exclusion in nv_do_stats_poll. That's
because doing so would result in a deadlock, since it is a timer
callback and hence already waited for by timer deletion.



Signed-off-by: David Decotigny <david.decotigny@google.com>
---
drivers/net/ethernet/nvidia/forcedeth.c | 11 ++++++++++-
1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/drivers/net/ethernet/nvidia/forcedeth.c b/drivers/net/ethernet/nvidia/forcedeth.c
index 0af12a8..7996782 100644
--- a/drivers/net/ethernet/nvidia/forcedeth.c
+++ b/drivers/net/ethernet/nvidia/forcedeth.c
@@ -3937,6 +3937,10 @@ static void nv_poll_controller(struct net_device *dev)
}
#endif

+/* No locking is needed as long as this is in the timer
+ * callback. However, any other callers must call this
+ * function with np->lock held.
+ */
static void nv_do_stats_poll(unsigned long data)
{
struct net_device *dev = (struct net_device *) data;
@@ -4589,12 +4593,17 @@ static int nv_get_sset_count(struct net_device *dev, int sset)

static void nv_get_ethtool_stats(struct net_device *dev, struct ethtool_stats *estats, u64 *buffer)
{
+ unsigned long flags;
struct fe_priv *np = netdev_priv(dev);

+ spin_lock_irqsave(&np->lock, flags);
+
/* update stats */
nv_do_stats_poll((unsigned long)dev);

memcpy(buffer, &np->estats, nv_get_sset_count(dev, ETH_SS_STATS)*sizeof(u64));
+
+ spin_unlock_irqrestore(&np->lock, flags);
}

static int nv_link_test(struct net_device *dev)
@@ -5189,13 +5198,13 @@ static int nv_close(struct net_device *dev)

spin_lock_irq(&np->lock);
np->in_shutdown = 1;
+ del_timer_sync(&np->stats_poll);
spin_unlock_irq(&np->lock);
nv_napi_disable(dev);
synchronize_irq(np->pci_dev->irq);

del_timer_sync(&np->oom_kick);
del_timer_sync(&np->nic_poll);
- del_timer_sync(&np->stats_poll);

netif_stop_queue(dev);
spin_lock_irq(&np->lock);
--
1.7.3.1


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