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    Subject[PATCH 3.18 46/56] udl-kms: handle allocation failure
    Date
    3.18-stable review patch.  If anyone has any objections, please let me know.

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

    From: Mikulas Patocka <mpatocka@redhat.com>

    commit 542bb9788a1f485eb1a2229178f665d8ea166156 upstream.

    Allocations larger than PAGE_ALLOC_COSTLY_ORDER are unreliable and they
    may fail anytime. This patch fixes the udl kms driver so that when a large
    alloactions fails, it tries to do multiple smaller allocations.

    Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
    Cc: stable@vger.kernel.org
    Signed-off-by: Dave Airlie <airlied@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/gpu/drm/udl/udl_main.c | 28 ++++++++++++++++++----------
    1 file changed, 18 insertions(+), 10 deletions(-)

    --- a/drivers/gpu/drm/udl/udl_main.c
    +++ b/drivers/gpu/drm/udl/udl_main.c
    @@ -171,17 +171,22 @@ static void udl_free_urb_list(struct drm
    static int udl_alloc_urb_list(struct drm_device *dev, int count, size_t size)
    {
    struct udl_device *udl = dev->dev_private;
    - int i = 0;
    struct urb *urb;
    struct urb_node *unode;
    char *buf;
    + size_t wanted_size = count * size;

    spin_lock_init(&udl->urbs.lock);

    +retry:
    udl->urbs.size = size;
    INIT_LIST_HEAD(&udl->urbs.list);

    - while (i < count) {
    + sema_init(&udl->urbs.limit_sem, 0);
    + udl->urbs.count = 0;
    + udl->urbs.available = 0;
    +
    + while (udl->urbs.count * size < wanted_size) {
    unode = kzalloc(sizeof(struct urb_node), GFP_KERNEL);
    if (!unode)
    break;
    @@ -197,11 +202,16 @@ static int udl_alloc_urb_list(struct drm
    }
    unode->urb = urb;

    - buf = usb_alloc_coherent(udl->udev, MAX_TRANSFER, GFP_KERNEL,
    + buf = usb_alloc_coherent(udl->udev, size, GFP_KERNEL,
    &urb->transfer_dma);
    if (!buf) {
    kfree(unode);
    usb_free_urb(urb);
    + if (size > PAGE_SIZE) {
    + size /= 2;
    + udl_free_urb_list(dev);
    + goto retry;
    + }
    break;
    }

    @@ -212,16 +222,14 @@ static int udl_alloc_urb_list(struct drm

    list_add_tail(&unode->entry, &udl->urbs.list);

    - i++;
    + up(&udl->urbs.limit_sem);
    + udl->urbs.count++;
    + udl->urbs.available++;
    }

    - sema_init(&udl->urbs.limit_sem, i);
    - udl->urbs.count = i;
    - udl->urbs.available = i;
    -
    - DRM_DEBUG("allocated %d %d byte urbs\n", i, (int) size);
    + DRM_DEBUG("allocated %d %d byte urbs\n", udl->urbs.count, (int) size);

    - return i;
    + return udl->urbs.count;
    }

    struct urb *udl_get_urb(struct drm_device *dev)

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