[PATCH 3.16 087/328] udl-kms: handle allocation failure

Ben Hutchings
2018-12-09T22:08:16Z

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>
Signed-off-by: Dave Airlie <airlied@redhat.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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->ddev->usbdev, MAX_TRANSFER, GFP_KERNEL,
+ buf = usb_alloc_coherent(udl->ddev->usbdev, 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)