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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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