Re: regression caused by: genirq: do not leave interupts enabled on free_irq

["Yinghai Lu" <yhlu.kernel@gmail.com>]

On Tue, Apr 15, 2008 at 12:44 AM, Andrew Morton
<akpm@linux-foundation.org> wrote:
>
> On Fri, 11 Apr 2008 12:48:43 -0700 "Yinghai Lu" <yhlu.kernel@gmail.com> wrote:
>
>  > On Fri, Apr 11, 2008 at 11:22 AM, Yinghai Lu <yhlu.kernel@gmail.com> wrote:
>  > > On Fri, Apr 11, 2008 at 12:30 AM, Eric W. Biederman
>  > >  <ebiederm@xmission.com> wrote:
>  > >  >
>  > >  >
>  > >
>  > >
>  > > >  On Fri, 2008-04-11 at 00:17 -0700, Yinghai Lu wrote:
>  > >  >  > On Fri, Apr 11, 2008 at 12:14 AM, Yinghai Lu <yhlu.kernel@gmail.com> wrote:
>  > >  >  > > On Fri, Apr 11, 2008 at 12:01 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
>  > >  >  > >  > On Thu, 10 Apr 2008, Yinghai Lu wrote:
>  > >  >  > >  >  > last week found:
>  > >  >  > >  >  > after latest kernel kexec RHEL 5.1 or other stack kernel, the nvidia
>  > >  >  > >  >  > forcedeth doesn't work anymore.
>  > >  >  > >  >  >
>  > >  >  > >  >  > I stared at forcedeth.c two days. and revert every patches about that
>  > >  >  > >  >  > doesn't help.
>  > >  >  > >  >
>  > >  >  > >  >  So forcedeth does not come up again, when you kexec from linus.git
>  > >  >  > >  >  into an older distro kernel. Or is it the other way round ?
>  > >  >  > >  RHEL 5.1 kexec RHEL 5.1 : works
>  > >  >  > >  RHEL 5.1 kexec linus kernel: works
>  > >  >  > >  linus (after -rc2) kexec linus tree: works:
>  > >  >  > >  linus  (after -rc2) kexec RHEL 5.1 : forcedeth will not come up
>  > >  >  > >  linus ( before -rc2 include rc2) kexec RHEL 5.1 works
>  > >  >  > >
>  > >  >  > the forcedeth can not get IP address...
>  > >  >
>  > >  >  Sounds like you are not getting any interrupts when you receive a
>  > >  >  packet.  (i.e. The interrupt line is staying disabled).
>  > >  >
>  > >  >  Is MSI an option here?  I'm wondering if we disable the MSI and
>  > >  >  something is not enabling it.
>  > >
>  > >
>  > >
>  > >  after
>  > >  setpci -s 0x00:08.0 0x60.b=0xfe
>  > >
>  > >  the eth0 can get ip address with ifup eth0.
>  >
>  > it is RHEL 5.1 problem...with msi.
>  >
>  > somehow msi entry msi_attrib_maskbit=is_mask_bit_support always get
>  > 0...., and use msi_irq_wo_maskbit_type instead of
>  > msi_irq_w_maskbit_type
>  >
>  > so when load that directly without kexec
>  > that 0x60 always to 0x00.
>  >
>  > and this time kernel after 2.6.25-rc2 ( not included) really shutdown
>  > the msi with 0xff the all maskbit...
>  >
>
>  So... where did this end up?   It's a post-2.6.24 regression, isn't it?
>
>  Do we think it's a bug in the RHEL 5.1 kernel?  Even so, that's a problem
>  for the 2.6.25 kernel.

it is RHEL 5.1 kernel problem, it has code for maskbit with msi there,
but that does work...

I sent out patch for 2.6.25 so it can be used to kexec old kernel that
doesn't support maskbit for MSI.

please comment...

[PATCH] x86_64: restore mask_bits in msi shutdown


for MSI, default_shutdown will call mask_bit for msi device. so all
mask bits will
left disabled after free_irq.
then if kexec next kernel that only can use msi_enable bit.
all device's MSI can not be used.

So try to restore MSI mask bits that is saved before using msi in first kernel.

http://lkml.org/lkml/2008/4/11/369

YH