[PATCH 3.16 063/328] udlfb: handle allocation failure

Ben Hutchings
2018-12-09T22:14:48Z

From: Mikulas Patocka <mpatocka@redhat.com>

commit 080fb5240bdcabed7387b814139c3ea172d59fc5 upstream.

Allocations larger than PAGE_ALLOC_COSTLY_ORDER are unreliable and they
may fail anytime. This patch fixes the udlfb 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: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
[bwh: Backported to 3.16:
- Pointers to struct dlfb_data are named "dev" rather than "dlfb"
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/video/fbdev/udlfb.c | 26 +++++++++++++++++---------
1 file changed, 17 insertions(+), 9 deletions(-)

--- a/drivers/video/fbdev/udlfb.c
+++ b/drivers/video/fbdev/udlfb.c
@@ -1851,17 +1851,22 @@ static void dlfb_free_urb_list(struct dl

static int dlfb_alloc_urb_list(struct dlfb_data *dev, int count, size_t size)
{
- int i = 0;
struct urb *urb;
struct urb_node *unode;
char *buf;
+ size_t wanted_size = count * size;

spin_lock_init(&dev->urbs.lock);

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

- while (i < count) {
+ sema_init(&dev->urbs.limit_sem, 0);
+ dev->urbs.count = 0;
+ dev->urbs.available = 0;
+
+ while (dev->urbs.count * size < wanted_size) {
unode = kzalloc(sizeof(struct urb_node), GFP_KERNEL);
if (!unode)
break;
@@ -1874,11 +1879,16 @@ static int dlfb_alloc_urb_list(struct dl
}
unode->urb = urb;

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

@@ -1889,14 +1899,12 @@ static int dlfb_alloc_urb_list(struct dl

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

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

- sema_init(&dev->urbs.limit_sem, i);
- dev->urbs.count = i;
- dev->urbs.available = i;
-
- return i;
+ return dev->urbs.count;
}

static struct urb *dlfb_get_urb(struct dlfb_data *dev)