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Message-ID: <462613A3.9060402@ru.mvista.com>
Date: Wed, 18 Apr 2007 16:48:35 +0400
From: Sergei Shtylyov <sshtylyov@...mvista.com>
To: Mike Mattie <codermattie@...il.com>
CC: Adrian Bunk <bunk@...sta.de>, lkml <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] 2.6.21-rc7 hpt366 driver broken
Hello.
Mike Mattie wrote:
> I have added Sergei Shtylyov to the address list after seeing his recent posts on hpt366 issues, and the
> git changelog for the hpt366.c driver. I am very confident that I have pinpointed the defect in the driver.
Indeed you have. Thank you.
>>>>>[ Cc's added, full bug report was in
>>>>>http://lkml.org/lkml/2007/4/16/18 ]
>>>>>On Mon, Apr 16, 2007 at 04:38:22AM -0700, Mike Mattie wrote:
>>>>>>On Sun, 15 Apr 2007 22:48:46 -0700
>>>>>>Mike Mattie <codermattie@...il.com> wrote:
>>>>>>>Hello,
>>>>>>>I am testing the 2.6.21-rc7 kernel release. The IDE hpt366
>>>>>>>driver is crashing hanging the boot. I have basically the
>>>>>>>same config as 2.6.20.7 which works fine (except for
>>>>>>>netconsole mentioned in a previous mail).
>>>>>>>here is the hand-copied info:
>>>>>>>* "unable to handle paging request" , null deref
>>>>>>>* EIP @ init_chipset_hpt366
>>>>>>>I am running a git-bisect to see if I can resolve it to a
>>>>>>>commit.
>>>>>>This was identified as the first broken commit:
>>>>>>commit 7b73ee05d0acb926923d43d78b61add776ea4bb1
>>>>>>Author: Sergei Shtylyov <sshtylyov@...mvista.com>
>>>>>>Date: Wed Feb 7 18:18:16 2007 +0100
>>>>>> hpt366: init code rewrite
>>>>>>Reverting is conflicted so it will be a bit longer before I
>>>>>>pin-point any other build-breaks.
>>>>>Thanks for your report.
>>>>>Can you use a digital camera for taking a photograph of the
>>>>>crash?
>>>>I can later on tonight, by about 11PM west coast. I also saw
>>>>some hex offsets after the function pointed to by EIP, is there
>>>>a way to decode that to a line number ? I have debugging symbols
>>>>enabled.
>>>>I am also doing printk breadcrumbs to pin it down to a block
>>>>or a line.
>>>I have narrowed the crash with breadcrumbs down to these lines:
>>> /*
>>> * Only try the DPLL if we don't have a table for the PCI
>>>clock that
>>> * we are running at for HPT370/A, always use it for
>>>anything newer... *
>>> * NOTE: Using the internal DPLL results in slow reads on 33
>>>MHz PCI.
>>> * We also don't like using the DPLL because this causes
>>>glitches
>>> * on PRST-/SRST- when the state engine gets reset...
>>> */
>>> if (info->chip_type >= HPT374 || info->settings[clock] ==
>>>NULL) { u16 f_low, delta = pci_clk < 50 ? 2 : 4;
>>> int adjust;
>>>
>>> printk(KERN_INFO "inside the if\n");
>>>
>>> /*
>>> * Select 66 MHz DPLL clock only if UltraATA/133
>>>mode is
>>> * supported/enabled, use 50 MHz DPLL clock
>>>otherwise... */
>>> if (info->max_mode == 0x04) {
>>> dpll_clk = 66;
>>> clock = ATA_CLOCK_66MHZ;
>>> } else if (dpll_clk) { /* HPT36x chips don't
>>>have DPLL */ dpll_clk = 50;
>>> clock = ATA_CLOCK_50MHZ;
>>> }
>>>
>>> if (info->settings[clock] == NULL) {
>> ^^^^^^^^ crashes here
>>since info is deref'd all over the place I am assuming it is the array
>>that is blowing up.
>>I printk'd the value of clock which is "4". that array is either not
>>setup correctly , or it is out-of-bounds (speculation)
> here on line 493: the hpt302n ( The chipset I have ) is the only struct without
> a .settings field , I am extremely confident this is the exact location of the bug.
> static struct hpt_info hpt302n __devinitdata = {
> .chip_type = HPT302N,
> .max_mode = HPT302_ALLOW_ATA133_6 ? 4 : 3,
> .dpll_clk = 77,
> };
Argh, a missed line! :-< And what a pity that I've only maneged to test on plain HPT302 chip and this managed to slip past the review too. :-(
> I do not know enough about the HPT chips to correctly select which settings group
> this field should be initialized to. Please take a look, the fix now should be very
> easy.
It should be hpt37x_settings, of course. I'll submit a patch in a couple jiffies...
MBR, Sergei
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