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authorRoland Dreier <rolandd@cisco.com>2007-05-19 08:51:53 -0700
committerRoland Dreier <rolandd@cisco.com>2007-05-19 08:51:53 -0700
commit8b8c8bca3a63073bac20f0fca178e00fdf7f5a09 (patch)
tree59c7f4b6a502e99e620d20d9c251fdebb79cc34a /drivers/infiniband
parent7b82cd8ee7374f803a3daf9a6cbc6eb4bbb10a63 (diff)
IB/ipath: Fix potential deadlock with multicast spinlocks
Lockdep found the following potential deadlock between mcast_lock and n_mcast_grps_lock: mcast_lock is taken from both interrupt context and process context, so spin_lock_irqsave() must be used to take it. n_mcast_grps_lock is only taken from process context, so at first it seems safe to take it with plain spin_lock(); however, it also nests inside mcast_lock, and hence we could deadlock: cpu A cpu B ipath_mcast_add(): spin_lock_irq(&mcast_lock); ipath_mcast_detach(): spin_lock(&n_mcast_grps_lock); <enter interrupt> ipath_mcast_find(): spin_lock_irqsave(&mcast_lock); spin_lock(&n_mcast_grps_lock); Fix this by using spin_lock_irq() to take n_mcast_grps_lock. Signed-off-by: Roland Dreier <rolandd@cisco.com>
Diffstat (limited to 'drivers/infiniband')
-rw-r--r--drivers/infiniband/hw/ipath/ipath_verbs_mcast.c16
1 files changed, 7 insertions, 9 deletions
diff --git a/drivers/infiniband/hw/ipath/ipath_verbs_mcast.c b/drivers/infiniband/hw/ipath/ipath_verbs_mcast.c
index 085e28b939e..dd691cfa507 100644
--- a/drivers/infiniband/hw/ipath/ipath_verbs_mcast.c
+++ b/drivers/infiniband/hw/ipath/ipath_verbs_mcast.c
@@ -165,10 +165,9 @@ static int ipath_mcast_add(struct ipath_ibdev *dev,
{
struct rb_node **n = &mcast_tree.rb_node;
struct rb_node *pn = NULL;
- unsigned long flags;
int ret;
- spin_lock_irqsave(&mcast_lock, flags);
+ spin_lock_irq(&mcast_lock);
while (*n) {
struct ipath_mcast *tmcast;
@@ -228,7 +227,7 @@ static int ipath_mcast_add(struct ipath_ibdev *dev,
ret = 0;
bail:
- spin_unlock_irqrestore(&mcast_lock, flags);
+ spin_unlock_irq(&mcast_lock);
return ret;
}
@@ -289,17 +288,16 @@ int ipath_multicast_detach(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)
struct ipath_mcast *mcast = NULL;
struct ipath_mcast_qp *p, *tmp;
struct rb_node *n;
- unsigned long flags;
int last = 0;
int ret;
- spin_lock_irqsave(&mcast_lock, flags);
+ spin_lock_irq(&mcast_lock);
/* Find the GID in the mcast table. */
n = mcast_tree.rb_node;
while (1) {
if (n == NULL) {
- spin_unlock_irqrestore(&mcast_lock, flags);
+ spin_unlock_irq(&mcast_lock);
ret = -EINVAL;
goto bail;
}
@@ -334,7 +332,7 @@ int ipath_multicast_detach(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)
break;
}
- spin_unlock_irqrestore(&mcast_lock, flags);
+ spin_unlock_irq(&mcast_lock);
if (p) {
/*
@@ -348,9 +346,9 @@ int ipath_multicast_detach(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)
atomic_dec(&mcast->refcount);
wait_event(mcast->wait, !atomic_read(&mcast->refcount));
ipath_mcast_free(mcast);
- spin_lock(&dev->n_mcast_grps_lock);
+ spin_lock_irq(&dev->n_mcast_grps_lock);
dev->n_mcast_grps_allocated--;
- spin_unlock(&dev->n_mcast_grps_lock);
+ spin_unlock_irq(&dev->n_mcast_grps_lock);
}
ret = 0;