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    Subject[PATCH 3.16.y-ckt 126/130] xen/gntdev: convert priv->lock to a mutex
    Date
    3.16.7-ckt17 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: David Vrabel <david.vrabel@citrix.com>

    commit 1401c00e59ea021c575f74612fe2dbba36d6a4ee upstream.

    Unmapping may require sleeping and we unmap while holding priv->lock, so
    convert it to a mutex.

    Signed-off-by: David Vrabel <david.vrabel@citrix.com>
    Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
    Cc: Ian Campbell <ian.campbell@citrix.com>
    [ luis: 3.16 prereq for:
    30b03d05e074 xen/gntdevt: Fix race condition in gntdev_release() ]
    Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
    ---
    drivers/xen/gntdev.c | 40 ++++++++++++++++++++--------------------
    1 file changed, 20 insertions(+), 20 deletions(-)

    diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
    index 073b4a19a8b0..b7f028a8f542 100644
    --- a/drivers/xen/gntdev.c
    +++ b/drivers/xen/gntdev.c
    @@ -67,7 +67,7 @@ struct gntdev_priv {
    * Only populated if populate_freeable_maps == 1 */
    struct list_head freeable_maps;
    /* lock protects maps and freeable_maps */
    - spinlock_t lock;
    + struct mutex lock;
    struct mm_struct *mm;
    struct mmu_notifier mn;
    };
    @@ -216,9 +216,9 @@ static void gntdev_put_map(struct gntdev_priv *priv, struct grant_map *map)
    }

    if (populate_freeable_maps && priv) {
    - spin_lock(&priv->lock);
    + mutex_lock(&priv->lock);
    list_del(&map->next);
    - spin_unlock(&priv->lock);
    + mutex_unlock(&priv->lock);
    }

    if (map->pages && !use_ptemod)
    @@ -387,9 +387,9 @@ static void gntdev_vma_close(struct vm_area_struct *vma)
    * not do any unmapping, since that has been done prior to
    * closing the vma, but it may still iterate the unmap_ops list.
    */
    - spin_lock(&priv->lock);
    + mutex_lock(&priv->lock);
    map->vma = NULL;
    - spin_unlock(&priv->lock);
    + mutex_unlock(&priv->lock);
    }
    vma->vm_private_data = NULL;
    gntdev_put_map(priv, map);
    @@ -433,14 +433,14 @@ static void mn_invl_range_start(struct mmu_notifier *mn,
    struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
    struct grant_map *map;

    - spin_lock(&priv->lock);
    + mutex_lock(&priv->lock);
    list_for_each_entry(map, &priv->maps, next) {
    unmap_if_in_range(map, start, end);
    }
    list_for_each_entry(map, &priv->freeable_maps, next) {
    unmap_if_in_range(map, start, end);
    }
    - spin_unlock(&priv->lock);
    + mutex_unlock(&priv->lock);
    }

    static void mn_invl_page(struct mmu_notifier *mn,
    @@ -457,7 +457,7 @@ static void mn_release(struct mmu_notifier *mn,
    struct grant_map *map;
    int err;

    - spin_lock(&priv->lock);
    + mutex_lock(&priv->lock);
    list_for_each_entry(map, &priv->maps, next) {
    if (!map->vma)
    continue;
    @@ -476,7 +476,7 @@ static void mn_release(struct mmu_notifier *mn,
    err = unmap_grant_pages(map, /* offset */ 0, map->count);
    WARN_ON(err);
    }
    - spin_unlock(&priv->lock);
    + mutex_unlock(&priv->lock);
    }

    static struct mmu_notifier_ops gntdev_mmu_ops = {
    @@ -498,7 +498,7 @@ static int gntdev_open(struct inode *inode, struct file *flip)

    INIT_LIST_HEAD(&priv->maps);
    INIT_LIST_HEAD(&priv->freeable_maps);
    - spin_lock_init(&priv->lock);
    + mutex_init(&priv->lock);

    if (use_ptemod) {
    priv->mm = get_task_mm(current);
    @@ -572,10 +572,10 @@ static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
    return -EFAULT;
    }

    - spin_lock(&priv->lock);
    + mutex_lock(&priv->lock);
    gntdev_add_map(priv, map);
    op.index = map->index << PAGE_SHIFT;
    - spin_unlock(&priv->lock);
    + mutex_unlock(&priv->lock);

    if (copy_to_user(u, &op, sizeof(op)) != 0)
    return -EFAULT;
    @@ -594,7 +594,7 @@ static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
    return -EFAULT;
    pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);

    - spin_lock(&priv->lock);
    + mutex_lock(&priv->lock);
    map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
    if (map) {
    list_del(&map->next);
    @@ -602,7 +602,7 @@ static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
    list_add_tail(&map->next, &priv->freeable_maps);
    err = 0;
    }
    - spin_unlock(&priv->lock);
    + mutex_unlock(&priv->lock);
    if (map)
    gntdev_put_map(priv, map);
    return err;
    @@ -670,7 +670,7 @@ static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
    out_flags = op.action;
    out_event = op.event_channel_port;

    - spin_lock(&priv->lock);
    + mutex_lock(&priv->lock);

    list_for_each_entry(map, &priv->maps, next) {
    uint64_t begin = map->index << PAGE_SHIFT;
    @@ -698,7 +698,7 @@ static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
    rc = 0;

    unlock_out:
    - spin_unlock(&priv->lock);
    + mutex_unlock(&priv->lock);

    /* Drop the reference to the event channel we did not save in the map */
    if (out_flags & UNMAP_NOTIFY_SEND_EVENT)
    @@ -748,7 +748,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
    pr_debug("map %d+%d at %lx (pgoff %lx)\n",
    index, count, vma->vm_start, vma->vm_pgoff);

    - spin_lock(&priv->lock);
    + mutex_lock(&priv->lock);
    map = gntdev_find_map_index(priv, index, count);
    if (!map)
    goto unlock_out;
    @@ -783,7 +783,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
    map->flags |= GNTMAP_readonly;
    }

    - spin_unlock(&priv->lock);
    + mutex_unlock(&priv->lock);

    if (use_ptemod) {
    err = apply_to_page_range(vma->vm_mm, vma->vm_start,
    @@ -811,11 +811,11 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
    return 0;

    unlock_out:
    - spin_unlock(&priv->lock);
    + mutex_unlock(&priv->lock);
    return err;

    out_unlock_put:
    - spin_unlock(&priv->lock);
    + mutex_unlock(&priv->lock);
    out_put_map:
    if (use_ptemod)
    map->vma = NULL;

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