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xen/gntalloc: Change gref_lock to a mutex

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The event channel release function cannot be called under a spinlock
because it can attempt to acquire a mutex due to the event channel
reference acquired when setting up unmap notifications.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Daniel De Graaf 2011-10-27 17:58:48 -04:00 committed by Konrad Rzeszutek Wilk
parent 80df464948
commit 8ca19a8937
1 changed files with 21 additions and 20 deletions
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41
drivers/xen/gntalloc.c
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@ -74,7 +74,7 @@ MODULE_PARM_DESC(limit, "Maximum number of grants that may be allocated by "
"the gntalloc device");
static LIST_HEAD(gref_list);
static DEFINE_SPINLOCK(gref_lock);
static DEFINE_MUTEX(gref_mutex);
static int gref_size;
struct notify_info {
@ -143,15 +143,15 @@ static int add_grefs(struct ioctl_gntalloc_alloc_gref *op,
}
/* Add to gref lists. */
spin_lock(&gref_lock);
mutex_lock(&gref_mutex);
list_splice_tail(&queue_gref, &gref_list);
list_splice_tail(&queue_file, &priv->list);
spin_unlock(&gref_lock);
mutex_unlock(&gref_mutex);
return 0;
undo:
spin_lock(&gref_lock);
mutex_lock(&gref_mutex);
gref_size -= (op->count - i);
list_for_each_entry(gref, &queue_file, next_file) {
@ -167,7 +167,7 @@ undo:
*/
if (unlikely(!list_empty(&queue_gref)))
list_splice_tail(&queue_gref, &gref_list);
spin_unlock(&gref_lock);
mutex_unlock(&gref_mutex);
return rc;
}
@ -251,7 +251,7 @@ static int gntalloc_release(struct inode *inode, struct file *filp)
pr_debug("%s: priv %p\n", __func__, priv);
spin_lock(&gref_lock);
mutex_lock(&gref_mutex);
while (!list_empty(&priv->list)) {
gref = list_entry(priv->list.next,
struct gntalloc_gref, next_file);
@ -261,7 +261,7 @@ static int gntalloc_release(struct inode *inode, struct file *filp)
__del_gref(gref);
}
kfree(priv);
spin_unlock(&gref_lock);
mutex_unlock(&gref_mutex);
return 0;
}
@ -286,21 +286,21 @@ static long gntalloc_ioctl_alloc(struct gntalloc_file_private_data *priv,
goto out;
}
spin_lock(&gref_lock);
mutex_lock(&gref_mutex);
/* Clean up pages that were at zero (local) users but were still mapped
* by remote domains. Since those pages count towards the limit that we
* are about to enforce, removing them here is a good idea.
*/
do_cleanup();
if (gref_size + op.count > limit) {
spin_unlock(&gref_lock);
mutex_unlock(&gref_mutex);
rc = -ENOSPC;
goto out_free;
}
gref_size += op.count;
op.index = priv->index;
priv->index += op.count * PAGE_SIZE;
spin_unlock(&gref_lock);
mutex_unlock(&gref_mutex);
rc = add_grefs(&op, gref_ids, priv);
if (rc < 0)
@ -343,7 +343,7 @@ static long gntalloc_ioctl_dealloc(struct gntalloc_file_private_data *priv,
goto dealloc_grant_out;
}
spin_lock(&gref_lock);
mutex_lock(&gref_mutex);
gref = find_grefs(priv, op.index, op.count);
if (gref) {
/* Remove from the file list only, and decrease reference count.
@ -363,7 +363,7 @@ static long gntalloc_ioctl_dealloc(struct gntalloc_file_private_data *priv,
do_cleanup();
spin_unlock(&gref_lock);
mutex_unlock(&gref_mutex);
dealloc_grant_out:
return rc;
}
@ -383,7 +383,7 @@ static long gntalloc_ioctl_unmap_notify(struct gntalloc_file_private_data *priv,
index = op.index & ~(PAGE_SIZE - 1);
pgoff = op.index & (PAGE_SIZE - 1);
spin_lock(&gref_lock);
mutex_lock(&gref_mutex);
gref = find_grefs(priv, index, 1);
if (!gref) {
@ -400,8 +400,9 @@ static long gntalloc_ioctl_unmap_notify(struct gntalloc_file_private_data *priv,
gref->notify.pgoff = pgoff;
gref->notify.event = op.event_channel_port;
rc = 0;
unlock_out:
spin_unlock(&gref_lock);
mutex_unlock(&gref_mutex);
return rc;
}
@ -433,9 +434,9 @@ static void gntalloc_vma_open(struct vm_area_struct *vma)
if (!gref)
return;
spin_lock(&gref_lock);
mutex_lock(&gref_mutex);
gref->users++;
spin_unlock(&gref_lock);
mutex_unlock(&gref_mutex);
}
static void gntalloc_vma_close(struct vm_area_struct *vma)
@ -444,11 +445,11 @@ static void gntalloc_vma_close(struct vm_area_struct *vma)
if (!gref)
return;
spin_lock(&gref_lock);
mutex_lock(&gref_mutex);
gref->users--;
if (gref->users == 0)
__del_gref(gref);
spin_unlock(&gref_lock);
mutex_unlock(&gref_mutex);
}
static struct vm_operations_struct gntalloc_vmops = {
@ -471,7 +472,7 @@ static int gntalloc_mmap(struct file *filp, struct vm_area_struct *vma)
return -EINVAL;
}
spin_lock(&gref_lock);
mutex_lock(&gref_mutex);
gref = find_grefs(priv, vma->vm_pgoff << PAGE_SHIFT, count);
if (gref == NULL) {
rv = -ENOENT;
@ -499,7 +500,7 @@ static int gntalloc_mmap(struct file *filp, struct vm_area_struct *vma)
rv = 0;
out_unlock:
spin_unlock(&gref_lock);
mutex_unlock(&gref_mutex);
return rv;
}