Mailing List Archive

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>
---
drivers/xen/gntalloc.c | 41 +++++++++++++++++++++--------------------
1 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c
index f6832f4..439352d 100644
--- a/drivers/xen/gntalloc.c
+++ b/drivers/xen/gntalloc.c
@@ -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;
}

--
1.7.6.4


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