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authorRalf Baechle <ralf@linux-mips.org>2005-10-17 12:42:32 +0100
committerJeff Garzik <jgarzik@pobox.com>2005-10-18 17:01:27 -0400
commitbc0a7438605c5e0cafdb32a3caf46254e146b116 (patch)
tree7331f97459c13f1f4bb18d8d2db6abd724ad6f7f
parentad4ebed00fbf570411edbf6eb6c391e16b71df25 (diff)
[PATCH] rcu in bpqether driver.
From Suzanne Wood <suzannew@cs.pdx.edu>: Clarify RCU implementation in bpqether.c. Because bpq_new_device() calls list_add_rcu() and bpq_free_device() calls list_del_rcu(), substitute list_for_each_entry_rcu() for list_for_each_entry() in bpq_get_ax25_dev() and in bpq_seq_start(). Add rcu dereference protection in bpq_seq_next(). The rcu_read_lock()/unlock() in bpq_device_event() are removed because netdev event handlers are called with RTNL locking in place. FYI: bpq_free_device() calls list_del_rcu() which, per list.h, requires synchronize_rcu() which can block or call_rcu() or call_rcu_bh() which cannot block. Herbert Xu notes that synchronization is done here by unregister_netdevice(). This calls synchronize_net() which in turn uses synchronize_rcu(). Signed-off-by: Ralf Baechle DL5RB <ralf@linux-mips.org> Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
-rw-r--r--drivers/net/hamradio/bpqether.c9
1 files changed, 3 insertions, 6 deletions
diff --git a/drivers/net/hamradio/bpqether.c b/drivers/net/hamradio/bpqether.c
index 1756f0ed54c..cb43a9d2877 100644
--- a/drivers/net/hamradio/bpqether.c
+++ b/drivers/net/hamradio/bpqether.c
@@ -144,7 +144,7 @@ static inline struct net_device *bpq_get_ax25_dev(struct net_device *dev)
{
struct bpqdev *bpq;
- list_for_each_entry(bpq, &bpq_devices, bpq_list) {
+ list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list) {
if (bpq->ethdev == dev)
return bpq->axdev;
}
@@ -399,7 +399,7 @@ static void *bpq_seq_start(struct seq_file *seq, loff_t *pos)
if (*pos == 0)
return SEQ_START_TOKEN;
- list_for_each_entry(bpqdev, &bpq_devices, bpq_list) {
+ list_for_each_entry_rcu(bpqdev, &bpq_devices, bpq_list) {
if (i == *pos)
return bpqdev;
}
@@ -418,7 +418,7 @@ static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos)
p = ((struct bpqdev *)v)->bpq_list.next;
return (p == &bpq_devices) ? NULL
- : list_entry(p, struct bpqdev, bpq_list);
+ : rcu_dereference(list_entry(p, struct bpqdev, bpq_list));
}
static void bpq_seq_stop(struct seq_file *seq, void *v)
@@ -561,8 +561,6 @@ static int bpq_device_event(struct notifier_block *this,unsigned long event, voi
if (!dev_is_ethdev(dev))
return NOTIFY_DONE;
- rcu_read_lock();
-
switch (event) {
case NETDEV_UP: /* new ethernet device -> new BPQ interface */
if (bpq_get_ax25_dev(dev) == NULL)
@@ -581,7 +579,6 @@ static int bpq_device_event(struct notifier_block *this,unsigned long event, voi
default:
break;
}
- rcu_read_unlock();
return NOTIFY_DONE;
}