[PATCH 3/4] dell-laptop: Fix allocating & freeing SMI buffer page

[PATCH 3/4] dell-laptop: Fix allocating & freeing SMI buffer page

[Pali Rohár]

This commit fix kernel crash when probing for rfkill devices in dell-laptop
driver failed. Function free_page() was incorrectly used on struct page *
instead of virtual address of SMI buffer.

This commit also simplify allocating page for SMI buffer by using
__get_free_page() function instead of sequential call of functions
alloc_page() and page_address().

Signed-off-by: Pali RohA!r <pali.rohar@gmail.com>
---
 drivers/platform/x86/dell-laptop.c |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
index aaef335..0a91599 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -306,7 +306,6 @@ static const struct dmi_system_id dell_quirks[] __initconst = {
 };
 
 static struct calling_interface_buffer *buffer;
-static struct page *bufferpage;
 static DEFINE_MUTEX(buffer_mutex);
 
 static int hwswitch_state;
@@ -2097,12 +2096,11 @@ static int __init dell_init(void)
 	 * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
 	 * is passed to SMI handler.
 	 */
-	bufferpage = alloc_page(GFP_KERNEL | GFP_DMA32);
-	if (!bufferpage) {
+	buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
+	if (!buffer) {
 		ret = -ENOMEM;
 		goto fail_buffer;
 	}
-	buffer = page_address(bufferpage);
 
 	ret = dell_setup_rfkill();
 
@@ -2165,7 +2163,7 @@ static int __init dell_init(void)
 fail_backlight:
 	dell_cleanup_rfkill();
 fail_rfkill:
-	free_page((unsigned long)bufferpage);
+	free_page((unsigned long)buffer);
 fail_buffer:
 	platform_device_del(platform_device);
 fail_platform_device2:
-- 
1.7.9.5

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Re: [PATCH 3/4] dell-laptop: Fix allocating & freeing SMI buffer page

[Michal Hocko]

On Sun 21-06-15 10:41:03, Pali Rohar wrote:
> This commit fix kernel crash when probing for rfkill devices in dell-laptop
> driver failed. Function free_page() was incorrectly used on struct page *
> instead of virtual address of SMI buffer.
> 
> This commit also simplify allocating page for SMI buffer by using
> __get_free_page() function instead of sequential call of functions
> alloc_page() and page_address().
> 
> Signed-off-by: Pali Rohar <pali.rohar@gmail.com>

Looks good to me.
FWIW
Acked-by: Michal Hocko <mhocko@suse.cz>

> ---
>  drivers/platform/x86/dell-laptop.c |    8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
> index aaef335..0a91599 100644
> --- a/drivers/platform/x86/dell-laptop.c
> +++ b/drivers/platform/x86/dell-laptop.c
> @@ -306,7 +306,6 @@ static const struct dmi_system_id dell_quirks[] __initconst = {
>  };
>  
>  static struct calling_interface_buffer *buffer;
> -static struct page *bufferpage;
>  static DEFINE_MUTEX(buffer_mutex);
>  
>  static int hwswitch_state;
> @@ -2097,12 +2096,11 @@ static int __init dell_init(void)
>  	 * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
>  	 * is passed to SMI handler.
>  	 */
> -	bufferpage = alloc_page(GFP_KERNEL | GFP_DMA32);
> -	if (!bufferpage) {
> +	buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
> +	if (!buffer) {
>  		ret = -ENOMEM;
>  		goto fail_buffer;
>  	}
> -	buffer = page_address(bufferpage);
>  
>  	ret = dell_setup_rfkill();
>  
> @@ -2165,7 +2163,7 @@ static int __init dell_init(void)
>  fail_backlight:
>  	dell_cleanup_rfkill();
>  fail_rfkill:
> -	free_page((unsigned long)bufferpage);
> +	free_page((unsigned long)buffer);
>  fail_buffer:
>  	platform_device_del(platform_device);
>  fail_platform_device2:
> -- 
> 1.7.9.5
> 

-- 
Michal Hocko
SUSE Labs

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Re: [PATCH 3/4] dell-laptop: Fix allocating & freeing SMI buffer page

[Darren Hart]

On Sun, Jun 21, 2015 at 10:41:03AM +0200, Pali Rohar wrote:
> This commit fix kernel crash when probing for rfkill devices in dell-laptop
> driver failed. Function free_page() was incorrectly used on struct page *
> instead of virtual address of SMI buffer.
> 
> This commit also simplify allocating page for SMI buffer by using
> __get_free_page() function instead of sequential call of functions
> alloc_page() and page_address().
> 
> Signed-off-by: Pali Rohar <pali.rohar@gmail.com>

Looks good - please resend with Cc to stable - that's the simplest path to
inclusion in stable.

> ---
>  drivers/platform/x86/dell-laptop.c |    8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
> index aaef335..0a91599 100644
> --- a/drivers/platform/x86/dell-laptop.c
> +++ b/drivers/platform/x86/dell-laptop.c
> @@ -306,7 +306,6 @@ static const struct dmi_system_id dell_quirks[] __initconst = {
>  };
>  
>  static struct calling_interface_buffer *buffer;
> -static struct page *bufferpage;
>  static DEFINE_MUTEX(buffer_mutex);
>  
>  static int hwswitch_state;
> @@ -2097,12 +2096,11 @@ static int __init dell_init(void)
>  	 * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
>  	 * is passed to SMI handler.
>  	 */
> -	bufferpage = alloc_page(GFP_KERNEL | GFP_DMA32);
> -	if (!bufferpage) {
> +	buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
> +	if (!buffer) {
>  		ret = -ENOMEM;
>  		goto fail_buffer;
>  	}
> -	buffer = page_address(bufferpage);
>  
>  	ret = dell_setup_rfkill();
>  
> @@ -2165,7 +2163,7 @@ static int __init dell_init(void)
>  fail_backlight:
>  	dell_cleanup_rfkill();
>  fail_rfkill:
> -	free_page((unsigned long)bufferpage);
> +	free_page((unsigned long)buffer);
>  fail_buffer:
>  	platform_device_del(platform_device);
>  fail_platform_device2:
> -- 
> 1.7.9.5
> 
> 

-- 
Darren Hart
Intel Open Source Technology Center

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[PATCH] dell-laptop: Fix allocating & freeing SMI buffer page

[Pali Rohár]

This commit fix kernel crash when probing for rfkill devices in dell-laptop
driver failed. Function free_page() was incorrectly used on struct page *
instead of virtual address of SMI buffer.

This commit also simplify allocating page for SMI buffer by using
__get_free_page() function instead of sequential call of functions
alloc_page() and page_address().

Signed-off-by: Pali RohA!r <pali.rohar@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: stable@vger.kernel.org
---
 drivers/platform/x86/dell-laptop.c |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
index d688d80..2c1d5f5 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -305,7 +305,6 @@ static const struct dmi_system_id dell_quirks[] __initconst = {
 };
 
 static struct calling_interface_buffer *buffer;
-static struct page *bufferpage;
 static DEFINE_MUTEX(buffer_mutex);
 
 static int hwswitch_state;
@@ -1896,12 +1895,11 @@ static int __init dell_init(void)
 	 * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
 	 * is passed to SMI handler.
 	 */
-	bufferpage = alloc_page(GFP_KERNEL | GFP_DMA32);
-	if (!bufferpage) {
+	buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
+	if (!buffer) {
 		ret = -ENOMEM;
 		goto fail_buffer;
 	}
-	buffer = page_address(bufferpage);
 
 	ret = dell_setup_rfkill();
 
@@ -1965,7 +1963,7 @@ fail_backlight:
 	cancel_delayed_work_sync(&dell_rfkill_work);
 	dell_cleanup_rfkill();
 fail_rfkill:
-	free_page((unsigned long)bufferpage);
+	free_page((unsigned long)buffer);
 fail_buffer:
 	platform_device_del(platform_device);
 fail_platform_device2:
-- 
1.7.10.4

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Re: [PATCH] dell-laptop: Fix allocating & freeing SMI buffer page

[Darren Hart]

On Tue, Jun 23, 2015 at 10:11:19AM +0200, Pali Rohar wrote:
> This commit fix kernel crash when probing for rfkill devices in dell-laptop
> driver failed. Function free_page() was incorrectly used on struct page *
> instead of virtual address of SMI buffer.
> 
> This commit also simplify allocating page for SMI buffer by using
> __get_free_page() function instead of sequential call of functions
> alloc_page() and page_address().
> 
> Signed-off-by: Pali Rohar <pali.rohar@gmail.com>
> Acked-by: Michal Hocko <mhocko@suse.cz>
> Cc: stable@vger.kernel.org

Queued, thanks Pali.

-- 
Darren Hart
Intel Open Source Technology Center

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