[PATCH 3.4 45/65] dell-laptop: Fix allocating & freeing SMI buffer page

From: lizf
Date: Mon Oct 19 2015 - 20:51:20 EST


From: Pali RohÃr <pali.rohar@xxxxxxxxx>

3.4.110-rc1 review patch. If anyone has any objections, please let me know.

------------------


commit b8830a4e71b15d0364ac8e6c55301eea73f211da upstream.

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 RohÃr <pali.rohar@xxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Signed-off-by: Darren Hart <dvhart@xxxxxxxxxxxxxxx>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
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 e6c08ee..3d67591 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -216,7 +216,6 @@ static struct dmi_system_id __devinitdata dell_quirks[] = {
};

static struct calling_interface_buffer *buffer;
-static struct page *bufferpage;
static DEFINE_MUTEX(buffer_mutex);

static int hwswitch_state;
@@ -714,11 +713,10 @@ 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);
+ buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);

- if (!bufferpage)
+ if (!buffer)
goto fail_buffer;
- buffer = page_address(bufferpage);

ret = dell_setup_rfkill();

@@ -787,7 +785,7 @@ fail_backlight:
fail_filter:
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:
--
1.9.1

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