[PATCH 3/3] staging: vme_user: alloc buffer when setting slave

[Aaron Sierra]

Some bridges support a minimum slave window larger than this driver's
128 KB default buffer size. Also bridges typically require the PCI and
VME bases to be aligned to the size of the window.

Instead of allocating a slave buffer at probe time, allocate an
appropriately sized/aligned buffer in the VME_SET_SLAVE ioctl.

This reintroduces a helper function whose functionality was removed in
the following commit:

    commit 625a9e012dc637fdc4ceadaac74f18155b0406f6
    Author: Dmitry Kalinkin <dmitry.kalinkin at gmail.com>
    Date:   Sat Jun 13 16:34:03 2015 +0300

        staging: vme_user: remove buf_unalloc helper

Cc: Dmitry Kalinkin <dmitry.kalinkin at gmail.com>
Signed-off-by: Aaron Sierra <asierra at xes-inc.com>
---
 drivers/staging/vme/devices/vme_user.c | 48 +++++++++++++++++++++++-----------
 1 file changed, 33 insertions(+), 15 deletions(-)

diff --git a/drivers/staging/vme/devices/vme_user.c b/drivers/staging/vme/devices/vme_user.c
index c68e2b8..a0550d9 100644
--- a/drivers/staging/vme/devices/vme_user.c
+++ b/drivers/staging/vme/devices/vme_user.c
@@ -120,6 +120,19 @@ struct vme_user_vma_priv {
 	atomic_t refcnt;
 };
 
+static void slave_buffer_free(struct image_desc *img)
+{
+	if (!img->kern_buf)
+		return;
+
+	vme_free_consistent(img->resource, img->size_buf, img->kern_buf,
+			    img->pci_buf);
+
+	img->kern_buf = NULL;
+	img->pci_buf = 0;
+	img->size_buf = 0;
+}
+
 static ssize_t resource_to_user(int minor, char __user *buf, size_t count,
 				loff_t *ppos)
 {
@@ -394,6 +407,22 @@ static int vme_user_ioctl(struct inode *inode, struct file *file,
 				return -EFAULT;
 			}
 
+			if (img->kern_buf && (img->size_buf != slave.size))
+				slave_buffer_free(img);
+
+			if (!img->kern_buf) {
+				img->kern_buf = vme_alloc_consistent(
+						img->resource, slave.size,
+						&pci_addr);
+				if (!img->kern_buf) {
+					dev_warn(img->device,
+						 "Unable to allocate memory for buffer\n");
+					return -ENOMEM;
+				}
+				img->pci_buf = pci_addr;
+				img->size_buf = slave.size;
+			}
+
 			/* XXX	We do not want to push aspace, cycle and width
 			 *	to userspace as they are
 			 */
@@ -402,6 +431,9 @@ static int vme_user_ioctl(struct inode *inode, struct file *file,
 				img->pci_buf, slave.aspace,
 				slave.cycle);
 
+			if (retval)
+				slave_buffer_free(img);
+
 			break;
 		}
 		break;
@@ -578,17 +610,6 @@ static int vme_user_probe(struct vme_dev *vdev)
 			err = -ENOMEM;
 			goto err_slave;
 		}
-		image[i].size_buf = PCI_BUF_SIZE;
-		image[i].kern_buf = vme_alloc_consistent(image[i].resource,
-			image[i].size_buf, &image[i].pci_buf);
-		if (!image[i].kern_buf) {
-			dev_warn(&vdev->dev,
-				 "Unable to allocate memory for buffer\n");
-			image[i].pci_buf = 0;
-			vme_slave_free(image[i].resource);
-			err = -ENOMEM;
-			goto err_slave;
-		}
 	}
 
 	/*
@@ -676,8 +697,6 @@ err_master:
 err_slave:
 	while (i > SLAVE_MINOR) {
 		i--;
-		vme_free_consistent(image[i].resource, image[i].size_buf,
-				    image[i].kern_buf, image[i].pci_buf);
 		vme_slave_free(image[i].resource);
 	}
 err_class:
@@ -707,8 +726,7 @@ static int vme_user_remove(struct vme_dev *dev)
 
 	for (i = SLAVE_MINOR; i < (SLAVE_MAX + 1); i++) {
 		vme_slave_set(image[i].resource, 0, 0, 0, 0, VME_A32, 0);
-		vme_free_consistent(image[i].resource, image[i].size_buf,
-				    image[i].kern_buf, image[i].pci_buf);
+		slave_buffer_free(&image[i]);
 		vme_slave_free(image[i].resource);
 	}
 
-- 
1.9.1