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ixgbe: delay rx_ring freeing 

"cat /proc/net/dev" uses RCU protection only.

Its quite possible we call a driver get_stats() method while device is
dismantling and freeing its data structures.

So get_stats() methods must be very careful not accessing driver private
data without appropriate locking.

In ixgbe case, we access rx_ring pointers. These pointers are freed in
ixgbe_clear_interrupt_scheme() and set to NULL, this can trigger NULL
dereference in ixgbe_get_stats64()

A possible fix is to use RCU locking in ixgbe_get_stats64() and defer
rx_ring freeing after a grace period in ixgbe_clear_interrupt_scheme()

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Reported-by: Tantilov, Emil S <emil.s.tantilov@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Eric Dumazet 2010-11-16 19:26:42 -08:00 committed by Jeff Kirsher
parent b178bb3dfc
commit 1a51502bdd
2 changed files with 25 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/net/ixgbe/ixgbe.h
View File

@ -192,6 +192,7 @@ struct ixgbe_ring {
unsigned int size; /* length in bytes */
dma_addr_t dma; /* phys. address of descriptor ring */
struct rcu_head rcu;
} ____cacheline_internodealigned_in_smp;
enum ixgbe_ring_f_enum {

34
drivers/net/ixgbe/ixgbe_main.c
View File

@ -4751,6 +4751,11 @@ err_set_interrupt:
return err;
}
static void ring_free_rcu(struct rcu_head *head)
{
kfree(container_of(head, struct ixgbe_ring, rcu));
}
/**
* ixgbe_clear_interrupt_scheme - Clear the current interrupt scheme settings
* @adapter: board private structure to clear interrupt scheme on
@ -4767,7 +4772,12 @@ void ixgbe_clear_interrupt_scheme(struct ixgbe_adapter *adapter)
adapter->tx_ring[i] = NULL;
}
for (i = 0; i < adapter->num_rx_queues; i++) {
kfree(adapter->rx_ring[i]);
struct ixgbe_ring *ring = adapter->rx_ring[i];
/* ixgbe_get_stats64() might access this ring, we must wait
* a grace period before freeing it.
*/
call_rcu(&ring->rcu, ring_free_rcu);
adapter->rx_ring[i] = NULL;
}
@ -6563,20 +6573,23 @@ static struct rtnl_link_stats64 *ixgbe_get_stats64(struct net_device *netdev,
/* accurate rx/tx bytes/packets stats */
dev_txq_stats_fold(netdev, stats);
rcu_read_lock();
for (i = 0; i < adapter->num_rx_queues; i++) {
struct ixgbe_ring *ring = adapter->rx_ring[i];
struct ixgbe_ring *ring = ACCESS_ONCE(adapter->rx_ring[i]);
u64 bytes, packets;
unsigned int start;
do {
start = u64_stats_fetch_begin_bh(&ring->syncp);
packets = ring->stats.packets;
bytes = ring->stats.bytes;
} while (u64_stats_fetch_retry_bh(&ring->syncp, start));
stats->rx_packets += packets;
stats->rx_bytes += bytes;
if (ring) {
do {
start = u64_stats_fetch_begin_bh(&ring->syncp);
packets = ring->stats.packets;
bytes = ring->stats.bytes;
} while (u64_stats_fetch_retry_bh(&ring->syncp, start));
stats->rx_packets += packets;
stats->rx_bytes += bytes;
}
}
rcu_read_unlock();
/* following stats updated by ixgbe_watchdog_task() */
stats->multicast = netdev->stats.multicast;
stats->rx_errors = netdev->stats.rx_errors;
@ -7282,6 +7295,7 @@ static void __exit ixgbe_exit_module(void)
dca_unregister_notify(&dca_notifier);
#endif
pci_unregister_driver(&ixgbe_driver);
rcu_barrier(); /* Wait for completion of call_rcu()'s */
}
#ifdef CONFIG_IXGBE_DCA