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