Re: Regression 2.6.39-rc1 for sony-laptop

[Mattia Dongili <malattia@linux.it>]

On Sat, Apr 02, 2011 at 11:44:57AM +0200, Andrea Gelmini wrote:
> 2011/4/1 Matthew Garrett <mjg59@srcf.ucam.org>:
> > touch any Sony code. I'll take a look at the Sony patches, thanks for
> > the report!
> 
> Hi Matthew,
>    and thanks a lot for your quick answer.
>    Maybe I messed up with bisect trying to find the origin of two regression.
>    One was this. The other one is this one.
> 
>    Hibernation (to disk, of course) doesn't work no more.
>    Screen blanks and nothing happens. No HD activity, and so on. I also
>    waited some minutes.
> 
>    Well, bisect blame this commit:
> 
> commit 2a4f0c81adcd1f812a63bc9106be2fd26f437730
> Author: Mattia Dongili <malattia@linux.it>
> Date:   Sat Feb 19 11:52:30 2011 +0900
> 
>     sony-laptop: cache handles and report them via sysfs
> 
>     Avoid calling into acpi each time we need to lookup a method handle
>     and report the available handles to ease collection of information when
>     debugging issues. Also move initialization of the platform driver
>     earlier to allow adding files from other setup functions.
> 
>     Signed-off-by: Mattia Dongili <malattia@linux.it>
>     Signed-off-by: Matthew Garrett <mjg@redhat.com>
> 
>  drivers/platform/x86/sony-laptop.c |   97 ++++++++++++++++++++++++++++++------
>  1 files changed, 81 insertions(+), 16 deletions(-)
> 
>    Do you have any suggestion to better track down this issue?
>    It's not possibile to simply revert it.

As already reported the following patch should fix the issue:

commit 88d25cbfda526567dabf056a868d8ff5f22a962e
Author: Mattia Dongili <malattia@linux.it>
Date:   Fri Apr 1 10:01:41 2011 +0900

    sony-laptop: fix early NULL pointer dereference
    
    The SNC acpi driver could get early notifications before it fully
    initializes and that could lead to dereferencing the sony_nc_handles
    structure pointer that is still NULL at that stage.
    Make sure we return early from the handle lookup function in these
    cases.
    
    Signed-off-by: Mattia Dongili <malattia@linux.it>

diff --git a/drivers/platform/x86/sony-laptop.c b/drivers/platform/x86/sony-laptop.c
index b2ce172..7082c55 100644
--- a/drivers/platform/x86/sony-laptop.c
+++ b/drivers/platform/x86/sony-laptop.c
@@ -810,6 +810,11 @@ static int sony_nc_handles_cleanup(struct platform_device *pd)
 static int sony_find_snc_handle(int handle)
 {
 	int i;
+
+	/* not initialized yet, return early */
+	if (!handles)
+		return -1;
+
 	for (i = 0; i < 0x10; i++) {
 		if (handles->cap[i] == handle) {
 			dprintk("found handle 0x%.4x (offset: 0x%.2x)\n",
-- 
mattia
:wq!