linux-kernel - [PATCH 1/1] xen/gntdev: kmalloc structure gntdev_copy

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Date:	Sat,  7 May 2016 10:17:26 +0200
From:	Heinrich Schuchardt <xypron.glpk@....de>
To:	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	David Vrabel <david.vrabel@...rix.com>,
	Juergen Gross <jgross@...e.com>
Cc:	xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
	Heinrich Schuchardt <xypron.glpk@....de>
Subject: [PATCH 1/1] xen/gntdev: kmalloc structure gntdev_copy_batch

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@....de>
---
 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