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authorIngo Molnar <mingo@elte.hu>2006-07-03 00:25:14 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-07-03 15:27:08 -0700
commitd378834840907326ac9d448056d957d13cc3718f (patch)
treec3b75251c66ed9e9ea9a5af385a520f006f99d55
parentc63661848581a9842dfc72d9a400285dd284fc47 (diff)
downloadlinux-d378834840907326ac9d448056d957d13cc3718f.tar.bz2
[PATCH] lockdep: annotate ieee1394 skb-queue-head locking
ieee1394 reuses the skb infrastructure of the networking code, and uses two skb-head queues: ->pending_packet_queue and hpsbpkt_queue. The latter is used in the usual fashion: processed from a kernel thread. The other one, ->pending_packet_queue is also processed from hardirq context (f.e. in hpsb_bus_reset()), which is not what the networking code usually does (which completes from softirq or process context). This locking assymetry can be totally correct if done carefully, but it can also be dangerous if networking helper functions are reused, which could assume traditional networking use. It would probably be more robust to push this completion into a workqueue - but technically the code can be 100% correct, and lockdep has to be taught about it. The solution is to split the ->pending_packet_queue skb-head->lock class from the networking lock-class by using a private lock-validator key. Has no effect on non-lockdep kernels. Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Stefan Richter <stefanr@s5r6.in-berlin.de> Cc: Jody McIntyre <scjody@modernduck.com> Cc: Ben Collins <bcollins@debian.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--drivers/ieee1394/hosts.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/ieee1394/hosts.c b/drivers/ieee1394/hosts.c
index 2c669287f5bd..4feead4a35c5 100644
--- a/drivers/ieee1394/hosts.c
+++ b/drivers/ieee1394/hosts.c
@@ -107,6 +107,14 @@ static int alloc_hostnum_cb(struct hpsb_host *host, void *__data)
*/
static DEFINE_MUTEX(host_num_alloc);
+/*
+ * The pending_packet_queue is special in that it's processed
+ * from hardirq context too (such as hpsb_bus_reset()). Hence
+ * split the lock class from the usual networking skb-head
+ * lock class by using a separate key for it:
+ */
+static struct lock_class_key pending_packet_queue_key;
+
struct hpsb_host *hpsb_alloc_host(struct hpsb_host_driver *drv, size_t extra,
struct device *dev)
{
@@ -128,6 +136,8 @@ struct hpsb_host *hpsb_alloc_host(struct hpsb_host_driver *drv, size_t extra,
h->driver = drv;
skb_queue_head_init(&h->pending_packet_queue);
+ lockdep_set_class(&h->pending_packet_queue.lock,
+ &pending_packet_queue_key);
INIT_LIST_HEAD(&h->addr_space);
for (i = 2; i < 16; i++)