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Groups > linux.kernel > #1169542

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

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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 Rohár <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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[PATCH 0/4] Fixes for dell-laptop.c driver Pali Rohár <pali.rohar@gmail.com> - 2015-06-21 10:50 +0200
  [PATCH 2/4] dell-laptop: Check return value of all SMBIOS calls Pali Rohár <pali.rohar@gmail.com> - 2015-06-21 10:50 +0200
    [PATCH v2] dell-laptop: Check return value of all SMBIOS calls and do not cache hwswitch state Pali Rohár <pali.rohar@gmail.com> - 2015-06-27 09:40 +0200
      Re: [PATCH v2] dell-laptop: Check return value of all SMBIOS calls  and do not cache hwswitch state Darren Hart <dvhart@infradead.org> - 2015-06-30 01:10 +0200
  [PATCH 3/4] dell-laptop: Fix allocating & freeing SMI buffer page Pali Rohár <pali.rohar@gmail.com> - 2015-06-21 10:50 +0200
  [PATCH 4/4] dell-laptop: Show info about WiGig and UWB in debugfs Pali Rohár <pali.rohar@gmail.com> - 2015-06-21 10:50 +0200
  [PATCH 1/4] dell-laptop: Update information about wireless control Pali Rohár <pali.rohar@gmail.com> - 2015-06-21 10:50 +0200

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