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Message-ID: <1355002958.14981.11.camel@gitbox>
Date: Sun, 09 Dec 2012 10:42:38 +1300
From: Tony Prisk <linux@...sktech.co.nz>
To: Julia Lawall <Julia.Lawall@...6.fr>
Cc: linux-fbdev@...r.kernel.org, kernel-janitors@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
Florian Tobias Schandinat <FlorianSchandinat@....de>
Subject: Re: [PATCH] drivers/video/wm8505fb.c: use devm_ functions
On Sat, 2012-12-08 at 17:31 +0100, Julia Lawall wrote:
> From: Julia Lawall <Julia.Lawall@...6.fr>
>
> The various devm_ functions allocate memory that is released when a driver
> detaches. This patch uses these functions for data that is allocated in
> the probe function of a platform device and is only freed in the remove
> function.
>
> The patch makes some other cleanups. First, the original code used
> devm_kzalloc, but kfree. This would lead to a double free. The problem
> was found using the following semantic match (http://coccinelle.lip6.fr/):
>
> // <smpl>
> @@
> expression x,e;
> @@
> x = devm_kzalloc(...)
> ... when != x = e
> ?-kfree(x,...);
> // </smpl>
>
> The error-handling code for the call to dma_alloc_coherent is copied to the
> end of the function, like the other error-handling code. Given the
> introduction of the devm functions, this is just for uniformity, because
> the label at the end of the function now just returns the error code.
>
> A semicolon is removed at the end of this error handling code.
>
> The call platform_set_drvdata(pdev, NULL); is moved up under the label
> failed_free_cmap, because platform_set_drvdata(pdev, fbi); doesn't happen
> in the function until after gotos to this label are reached.
>
> The initializations of fbi and ret are not necessary and are removed.
>
> Signed-off-by: Julia Lawall <Julia.Lawall@...6.fr>
>
> ---
> drivers/video/wm8505fb.c | 44 ++++++++------------------------------------
> 1 file changed, 8 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/video/wm8505fb.c b/drivers/video/wm8505fb.c
> index 77539c1..3bad805 100644
> --- a/drivers/video/wm8505fb.c
> +++ b/drivers/video/wm8505fb.c
> @@ -274,9 +274,6 @@ static int __devinit wm8505fb_probe(struct platform_device *pdev)
> unsigned long fb_mem_len;
> void *fb_mem_virt;
>
> - ret = -ENOMEM;
> - fbi = NULL;
> -
> fbi = devm_kzalloc(&pdev->dev, sizeof(struct wm8505fb_info) +
> sizeof(u32) * 16, GFP_KERNEL);
> if (!fbi) {
> @@ -308,31 +305,19 @@ static int __devinit wm8505fb_probe(struct platform_device *pdev)
> fbi->fb.pseudo_palette = addr;
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> - if (res == NULL) {
> - dev_err(&pdev->dev, "no I/O memory resource defined\n");
> - ret = -ENODEV;
> - goto failed_fbi;
> - }
> -
> - res = request_mem_region(res->start, resource_size(res), DRIVER_NAME);
> - if (res == NULL) {
> - dev_err(&pdev->dev, "failed to request I/O memory\n");
> - ret = -EBUSY;
> - goto failed_fbi;
> - }
>
> - fbi->regbase = ioremap(res->start, resource_size(res));
> + fbi->regbase = devm_request_and_ioremap(&pdev->dev, res);
> if (fbi->regbase == NULL) {
> dev_err(&pdev->dev, "failed to map I/O memory\n");
> ret = -EBUSY;
> - goto failed_free_res;
> + goto failed;
> }
>
> np = of_parse_phandle(pdev->dev.of_node, "default-mode", 0);
> if (!np) {
> pr_err("%s: No display description in Device Tree\n", __func__);
> ret = -EINVAL;
> - goto failed_free_res;
> + goto failed;
> }
>
> /*
> @@ -351,7 +336,7 @@ static int __devinit wm8505fb_probe(struct platform_device *pdev)
> ret |= of_property_read_u32(np, "bpp", &bpp);
> if (ret) {
> pr_err("%s: Unable to read display properties\n", __func__);
> - goto failed_free_res;
> + goto failed;
> }
>
> of_mode.vmode = FB_VMODE_NONINTERLACED;
> @@ -369,8 +354,9 @@ static int __devinit wm8505fb_probe(struct platform_device *pdev)
> GFP_KERNEL);
> if (!fb_mem_virt) {
> pr_err("%s: Failed to allocate framebuffer\n", __func__);
> - return -ENOMEM;
> - };
> + ret = -ENOMEM;
> + goto failed;
> + }
>
> fbi->fb.var.xres_virtual = of_mode.xres;
> fbi->fb.var.yres_virtual = of_mode.yres * 2;
> @@ -384,7 +370,7 @@ static int __devinit wm8505fb_probe(struct platform_device *pdev)
> if (fb_alloc_cmap(&fbi->fb.cmap, 256, 0) < 0) {
> dev_err(&pdev->dev, "Failed to allocate color map\n");
> ret = -ENOMEM;
> - goto failed_free_io;
> + goto failed;
> }
>
> wm8505fb_init_hw(&fbi->fb);
> @@ -420,13 +406,7 @@ static int __devinit wm8505fb_probe(struct platform_device *pdev)
> failed_free_cmap:
> if (fbi->fb.cmap.len)
> fb_dealloc_cmap(&fbi->fb.cmap);
> -failed_free_io:
> - iounmap(fbi->regbase);
> -failed_free_res:
> - release_mem_region(res->start, resource_size(res));
> -failed_fbi:
> platform_set_drvdata(pdev, NULL);
> - kfree(fbi);
> failed:
> return ret;
> }
> @@ -434,7 +414,6 @@ failed:
> static int __devexit wm8505fb_remove(struct platform_device *pdev)
> {
> struct wm8505fb_info *fbi = platform_get_drvdata(pdev);
> - struct resource *res;
>
> device_remove_file(&pdev->dev, &dev_attr_contrast);
>
> @@ -445,13 +424,6 @@ static int __devexit wm8505fb_remove(struct platform_device *pdev)
> if (fbi->fb.cmap.len)
> fb_dealloc_cmap(&fbi->fb.cmap);
>
> - iounmap(fbi->regbase);
> -
> - res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> - release_mem_region(res->start, resource_size(res));
> -
> - kfree(fbi);
> -
> return 0;
> }
>
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Julia,
Thanks for the cleanup on this driver. Perhaps I could suggest just one
additional thing.
There are only two paths which lead to failed_free_cmap. Moving
...
fbi->contrast = 0x80;
ret = wm8505fb_set_par(&fbi->fb);
if (ret) {
dev_err(&pdev->dev, "Failed to set parameters\n");
goto failed_free_cmap;
}
...
above the following line removes the need to have the failed_free_cmap
path at all.
...
if (fb_alloc_cmap(&fbi->fb.cmap, 256, 0) < 0) {
...
If that is done, only this code leads to the failed_free_cmap path:
...
ret = register_framebuffer(&fbi->fb);
if (ret < 0) {
dev_err(&pdev->dev,
"Failed to register framebuffer device: %d\n", ret);
goto failed_free_cmap;
}
...
Rather than the goto, add the fail path code in directly, and return.
ret = register_framebuffer(&fbi->fb);
if (ret < 0) {
dev_err(&pdev->dev,
"Failed to register framebuffer device: %d\n", ret);
if (fbi->fb.cmap.len)
fb_dealloc_cmap(&fbi->fb.cmap);
return ret;
}
Now there is no need for any goto commands, and all the rest can be
replaced with 'return ret' or equiv.
Regards
Tony P
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