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Subject[PATCH v2 2/5] video: smscufx: Less checks in ufx_usb_probe() after error detection
From
Date
From: Markus Elfring <elfring@users.sourceforge.net>
Date: Sun, 26 Nov 2017 08:18:20 +0100

Up to four checks could be repeated by the ufx_usb_probe() function
during error handling even if the relevant properties can be determined
for the involved variables before by source code analysis.

* Return directly after a call of the function "kzalloc" failed
at the beginning.

* Adjust jump targets so that extra checks can be omitted at the end.

* Delete initialisations for the variables "info" and "retval"
which became unnecessary with this refactoring.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---

v2:
A call of the function "fb_dealloc_cmap" was preserved for the exception
handling at the end.

drivers/video/fbdev/smscufx.c | 46 ++++++++++++++++++-------------------------
1 file changed, 19 insertions(+), 27 deletions(-)

diff --git a/drivers/video/fbdev/smscufx.c b/drivers/video/fbdev/smscufx.c
index 32de07d77184..a48a2dec3f5e 100644
--- a/drivers/video/fbdev/smscufx.c
+++ b/drivers/video/fbdev/smscufx.c
@@ -1619,8 +1619,8 @@ static int ufx_usb_probe(struct usb_interface *interface,
{
struct usb_device *usbdev;
struct ufx_data *dev;
- struct fb_info *info = NULL;
- int retval = -ENOMEM;
+ struct fb_info *info;
+ int retval;
u32 id_rev, fpga_rev;

/* usb initialization */
@@ -1629,7 +1629,7 @@ static int ufx_usb_probe(struct usb_interface *interface,

dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (!dev)
- goto error;
+ return -ENOMEM;

/* we need to wait for both usb and fbdev to spin down on disconnect */
kref_init(&dev->kref); /* matching kref_put in usb .disconnect fn */
@@ -1649,9 +1649,8 @@ static int ufx_usb_probe(struct usb_interface *interface,
dev_dbg(dev->gdev, "fb_defio enable=%d\n", fb_defio);

if (!ufx_alloc_urb_list(dev, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
- retval = -ENOMEM;
dev_err(dev->gdev, "ufx_alloc_urb_list failed\n");
- goto error;
+ goto e_nomem;
}

/* We don't register a new USB class. Our client interface is fbdev */
@@ -1659,9 +1658,8 @@ static int ufx_usb_probe(struct usb_interface *interface,
/* allocates framebuffer driver structure, not framebuffer memory */
info = framebuffer_alloc(0, &usbdev->dev);
if (!info) {
- retval = -ENOMEM;
dev_err(dev->gdev, "framebuffer_alloc failed\n");
- goto error;
+ goto e_nomem;
}

dev->info = info;
@@ -1672,7 +1670,7 @@ static int ufx_usb_probe(struct usb_interface *interface,
retval = fb_alloc_cmap(&info->cmap, 256, 0);
if (retval < 0) {
dev_err(dev->gdev, "fb_alloc_cmap failed %x\n", retval);
- goto error;
+ goto destroy_modedb;
}

INIT_DELAYED_WORK(&dev->free_framebuffer_work,
@@ -1733,26 +1731,20 @@ static int ufx_usb_probe(struct usb_interface *interface,
return 0;

error:
- if (dev) {
- if (info) {
- if (info->cmap.len != 0)
- fb_dealloc_cmap(&info->cmap);
- if (info->monspecs.modedb)
- fb_destroy_modedb(info->monspecs.modedb);
- vfree(info->screen_base);
-
- fb_destroy_modelist(&info->modelist);
-
- framebuffer_release(info);
- }
-
- kref_put(&dev->kref, ufx_free); /* ref for framebuffer */
- kref_put(&dev->kref, ufx_free); /* last ref from kref_init */
-
- /* dev has been deallocated. Do not dereference */
- }
-
+ fb_dealloc_cmap(&info->cmap);
+destroy_modedb:
+ fb_destroy_modedb(info->monspecs.modedb);
+ vfree(info->screen_base);
+ fb_destroy_modelist(&info->modelist);
+ framebuffer_release(info);
+put_ref:
+ kref_put(&dev->kref, ufx_free); /* ref for framebuffer */
+ kref_put(&dev->kref, ufx_free); /* last ref from kref_init */
return retval;
+
+e_nomem:
+ retval = -ENOMEM;
+ goto put_ref;
}

static void ufx_usb_disconnect(struct usb_interface *interface)
--
2.15.0
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