[Xen-devel] [PATCH] xen/gntdev: Don't allocate struct gntdev_copy_batch on stack

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

struct gntdev_copy_batch is over 1300 bytes in size, we shouldn't
put it on stack.

Some compilers (e.g. 5.2.1) complain:
 drivers/xen/gntdev.c: In function âgntdev_ioctl_grant_copy.isra.5â:
 drivers/xen/gntdev.c:949:1: warning: the frame size of 1416 bytes
  is larger than 1024 bytes [-Wframe-larger-than=]

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
 drivers/xen/gntdev.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index dc49538..43a2c1c 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -915,15 +915,19 @@ static int gntdev_grant_copy_seg(struct gntdev_copy_batch 
*batch,
 static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u)
 {
        struct ioctl_gntdev_grant_copy copy;
-       struct gntdev_copy_batch batch;
+       struct gntdev_copy_batch *batch;
        unsigned int i;
        int ret = 0;
 
        if (copy_from_user(&copy, u, sizeof(copy)))
                return -EFAULT;
 
-       batch.nr_ops = 0;
-       batch.nr_pages = 0;
+       batch = kmalloc(sizeof(*batch), GFP_KERNEL);
+       if (!batch)
+               return -ENOMEM;
+
+       batch->nr_ops = 0;
+       batch->nr_pages = 0;
 
        for (i = 0; i < copy.count; i++) {
                struct gntdev_grant_copy_segment seg;
@@ -933,18 +937,20 @@ static long gntdev_ioctl_grant_copy(struct gntdev_priv 
*priv, void __user *u)
                        goto out;
                }
 
-               ret = gntdev_grant_copy_seg(&batch, &seg, 
&copy.segments[i].status);
+               ret = gntdev_grant_copy_seg(batch, &seg,
+                       &copy.segments[i].status);
                if (ret < 0)
                        goto out;
 
                cond_resched();
        }
-       if (batch.nr_ops)
-               ret = gntdev_copy(&batch);
+       if (batch->nr_ops)
+               ret = gntdev_copy(batch);
        return ret;
 
   out:
-       gntdev_put_pages(&batch);
+       gntdev_put_pages(batch);
+       kfree(batch);
        return ret;
 }
 
-- 
2.5.0


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