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SubjectRe: [PATCH] x86/PCI: add spinlock held check to 'pcibios_fwaddrmap_lookup()'
On Fri, 2 Mar 2012 12:00:27 -0800
Greg KH <gregkh@linuxfoundation.org> wrote:

> On Fri, Mar 02, 2012 at 12:45:01PM -0700, Myron Stowe wrote:
> > 'pcibios_fwaddrmap_lookup()' is used to maintain FW-assigned BIOS BAR
> > values for reinstatement when normal resource assignment attempts
> > fail and must be called with the 'pcibios_fwaddrmap_lock' spinlock
> > held.
> >
> > This patch adds a WARN_ON notification if the spinlock is not currently
> > held by the caller.
> >
> > Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
> > ---
> >
> > arch/x86/pci/i386.c | 2 ++
> > 1 files changed, 2 insertions(+), 0 deletions(-)
> >
> > diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
> > index 33e6a0b..831971e 100644
> > --- a/arch/x86/pci/i386.c
> > +++ b/arch/x86/pci/i386.c
> > @@ -57,6 +57,8 @@ static struct pcibios_fwaddrmap *pcibios_fwaddrmap_lookup(struct pci_dev *dev)
> > {
> > struct pcibios_fwaddrmap *map;
> >
> > + WARN_ON(!spin_is_locked(&pcibios_fwaddrmap_lock));
> > +
>
> What is this going to help with? How can someone then recover from this
> issue? Just adding a warning message isn't going to fix any problems
> here, why not fix the root cause?

It's just a self-documenting assert; doesn't trigger anything and has
more functionality than
/* Must hold the fwaddrmap_lock here */

--
Jesse Barnes, Intel Open Source Technology Center
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