[Xen-devel] [PATCH 1/1] xen/gntdev: kmalloc structure gntdev_copy_batch

[Heinrich Schuchardt <xypron.glpk@xxxxxx>]

Commit a4cdb556cae0 ("xen/gntdev: add ioctl for grant copy")
leads to a warning
xen/gntdev.c: In function ‘gntdev_ioctl_grant_copy’:
xen/gntdev.c:949:1: warning: the frame size of 1248 bytes
is larger than 1024 bytes [-Wframe-larger-than=]

This can be avoided by using kmalloc instead of the stack.

Testing requires CONFIG_XEN_GNTDEV.

Fixes: a4cdb556cae0 ("xen/gntdev: add ioctl for grant copy")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@xxxxxx>
---
 drivers/xen/gntdev.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index dc49538..e8aec48 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -915,36 +915,43 @@ 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;
 
+       batch = kmalloc(sizeof(struct gntdev_copy_batch), GFP_KERNEL);
+       if (!batch)
+               return -ENOMEM;
+
        if (copy_from_user(&copy, u, sizeof(copy)))
                return -EFAULT;
 
-       batch.nr_ops = 0;
-       batch.nr_pages = 0;
+       batch->nr_ops = 0;
+       batch->nr_pages = 0;
 
        for (i = 0; i < copy.count; i++) {
                struct gntdev_grant_copy_segment seg;
 
                if (copy_from_user(&seg, &copy.segments[i], sizeof(seg))) {
                        ret = -EFAULT;
-                       goto out;
+                       goto failed;
                }
 
-               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;
+                       goto failed;
 
                cond_resched();
        }
-       if (batch.nr_ops)
-               ret = gntdev_copy(&batch);
-       return ret;
+       if (batch->nr_ops)
+               ret = gntdev_copy(batch);
+       goto out;
 
-  out:
-       gntdev_put_pages(&batch);
+failed:
+       gntdev_put_pages(batch);
+out:
+       kfree(batch);
        return ret;
 }
 
-- 
2.1.4


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