Re: patch sparc64-make-prom-entry-spinlock-nmi-safe.patch added to 2.6.32-stable tree

Re: patch sparc64-make-prom-entry-spinlock-nmi-safe.patch added to 2.6.32-stable tree

[Stefan Bader]

This converted the raw_spinlock usage which is used in the upstream patch but
not available in 2.6.32 to normal spinlock usage. Should it get annotated to
document that?

-Stefan

gregkh@suse.de wrote:
> This is a note to let you know that we have just queued up the patch titled
> 
>     Subject: [PATCH] sparc64: Make prom entry spinlock NMI safe.
> 
> to the 2.6.32-stable tree.  Its filename is
> 
>     sparc64-make-prom-entry-spinlock-nmi-safe.patch
> 
> A git repo of this tree can be found at 
>     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> 
> 
> From c682420e87cdd8db0212e29eb70c325cdfc0860c Mon Sep 17 00:00:00 2001
> From: David S. Miller <davem@davemloft.net>
> Date: Wed, 3 Mar 2010 09:06:03 -0800
> Subject: [PATCH] sparc64: Make prom entry spinlock NMI safe.
> 
> From: David S. Miller <davem@davemloft.net>
> 
> [ Upstream commit 8a4fd1e4922413cfdfa6c51a59efb720d904a5eb ]
> 
> If we do something like try to print to the OF console from an NMI
> while we're already in OpenFirmware, we'll deadlock on the spinlock.
> 
> Use a raw spinlock and disable NMIs when we take it.
> 
> Signed-off-by: David S. Miller <davem@davemloft.net>
> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
> 
> ---
>  arch/sparc/prom/p1275.c |   10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> --- a/arch/sparc/prom/p1275.c
> +++ b/arch/sparc/prom/p1275.c
> @@ -32,8 +32,7 @@ extern void prom_cif_interface(void);
>  extern void prom_cif_callback(void);
>  
>  /*
> - * This provides SMP safety on the p1275buf. prom_callback() drops this lock
> - * to allow recursuve acquisition.
> + * This provides SMP safety on the p1275buf.
>   */
>  DEFINE_SPINLOCK(prom_entry_lock);
>  
> @@ -47,7 +46,9 @@ long p1275_cmd(const char *service, long
>  	
>  	p = p1275buf.prom_buffer;
>  
> -	spin_lock_irqsave(&prom_entry_lock, flags);
> +	raw_local_save_flags(flags);
> +	raw_local_irq_restore(PIL_NMI);
> +	spin_lock(&prom_entry_lock);
>  
>  	p1275buf.prom_args[0] = (unsigned long)p;		/* service */
>  	strcpy (p, service);
> @@ -139,7 +140,8 @@ long p1275_cmd(const char *service, long
>  	va_end(list);
>  	x = p1275buf.prom_args [nargs + 3];
>  
> -	spin_unlock_irqrestore(&prom_entry_lock, flags);
> +	spin_unlock(&prom_entry_lock);
> +	raw_local_irq_restore(flags);
>  
>  	return x;
>  }
> 
> 
> Patches currently in stable-queue which might be from davem@davemloft.net are
> 
> queue-2.6.32/pci-add-support-for-82576ns-serdes-to-existing-sr-iov-quirk.patch
> queue-2.6.32/sparc64-make-prom-entry-spinlock-nmi-safe.patch
> queue-2.6.32/ixgbe-add-support-for-82599-kr-device-0x1517.patch
> queue-2.6.32/e1000e-enable-new-82567v-3-device.patch
> queue-2.6.32/tg3-fix-tg3_poll_controller-passing-wrong-pointer-to-tg3_interrupt.patch
> queue-2.6.32/tg3-fix-5906-transmit-hangs.patch
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Re: [stable] patch sparc64-make-prom-entry-spinlock-nmi-safe.patch added to 2.6.32-stable tree

[Greg KH]

On Tue, Mar 30, 2010 at 02:07:42PM +0200, Stefan Bader wrote:
> This converted the raw_spinlock usage which is used in the upstream patch but
> not available in 2.6.32 to normal spinlock usage. Should it get annotated to
> document that?

why, you obviously figured that out :)

It's not the normal thing to do for backports otherwise we would be here
all day long...

thanks,

greg k-h

Re: [stable] patch sparc64-make-prom-entry-spinlock-nmi-safe.patch added to 2.6.32-stable tree

[Stefan Bader]

Greg KH wrote:
> On Tue, Mar 30, 2010 at 02:07:42PM +0200, Stefan Bader wrote:
>> This converted the raw_spinlock usage which is used in the upstream patch but
>> not available in 2.6.32 to normal spinlock usage. Should it get annotated to
>> document that?
> 
> why, you obviously figured that out :)
> 
> It's not the normal thing to do for backports otherwise we would be here
> all day long...

Sometimes its more or less to change. Well at least David saying "nah" and not
"hm argh" achieved half of what the intention of the suggested annotation was. :)

Thanks,
Stefan

> thanks,
> 
> greg k-h
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Re: patch sparc64-make-prom-entry-spinlock-nmi-safe.patch added to 2.6.32-stable tree

[David Miller]

From: Stefan Bader <stefan.bader@canonical.com>
Date: Tue, 30 Mar 2010 14:07:42 +0200

> This converted the raw_spinlock usage which is used in the upstream patch but
> not available in 2.6.32 to normal spinlock usage. Should it get annotated to
> document that?

I don't think so.