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| author | Ralf Baechle <ralf@linux-mips.org> | 2005-10-17 12:42:32 +0100 |
|---|---|---|
| committer | Jeff Garzik <jgarzik@pobox.com> | 2005-10-18 17:01:27 -0400 |
| commit | bc0a7438605c5e0cafdb32a3caf46254e146b116 (patch) | |
| tree | 7331f97459c13f1f4bb18d8d2db6abd724ad6f7f /drivers/net/hamradio/bpqether.c | |
| parent | ad4ebed00fbf570411edbf6eb6c391e16b71df25 (diff) | |
| download | lwn-bc0a7438605c5e0cafdb32a3caf46254e146b116.tar.gz lwn-bc0a7438605c5e0cafdb32a3caf46254e146b116.zip | |
[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>
Diffstat (limited to 'drivers/net/hamradio/bpqether.c')
| -rw-r--r-- | drivers/net/hamradio/bpqether.c | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/drivers/net/hamradio/bpqether.c b/drivers/net/hamradio/bpqether.c index 1756f0ed54cc..cb43a9d28774 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; } |