Messages in this thread |  | | Date | Wed, 3 Oct 2018 23:50:11 -0700 | From | Lance Roy <> | Subject | Re: [PATCH 01/16] x86/PCI: Replace spin_is_locked() with lockdep |
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On Wed, Oct 03, 2018 at 11:00:51AM -0500, Bjorn Helgaas wrote: > On Tue, Oct 02, 2018 at 10:38:47PM -0700, Lance Roy wrote: > > lockdep_assert_held() is better suited to checking locking requirements, > > since it won't get confused when someone else holds the lock. This is > > also a step towards possibly removing spin_is_locked(). > > > > Signed-off-by: Lance Roy <ldr709@gmail.com> > > Cc: Bjorn Helgaas <bhelgaas@google.com> > > Cc: Thomas Gleixner <tglx@linutronix.de> > > Cc: Ingo Molnar <mingo@redhat.com> > > Cc: Borislav Petkov <bp@alien8.de> > > Cc: "H. Peter Anvin" <hpa@zytor.com> > > Cc: <x86@kernel.org> > > Cc: <linux-pci@vger.kernel.org> > > I assume you plan to merge the whole series together. I don't object > to that, but I don't know enough to be able to formally ack this. > > It would be useful to include a tiny bit more detail in the changelog. > The spin_is_locked() documentation doesn't mention anything about > differences with respect to the lock being held by self vs by someone > else, so I can't tell where the confusion arises. The difference is that spin_is_locked() will return true when someone else holds the lock, while lockdep_assert_held() asserts that the current thread holds the lock. How about the following for an new changelog?
lockdep_assert_held() is better suited to checking locking requirements, since it only checks if the current thread holds the lock regardless of whether someone else does. This is also a step towards possibly removing spin_is_locked().
Thanks, Lance
> Bjorn > > > --- > > arch/x86/pci/i386.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c > > index ed4ac215305d..24bb58a007de 100644 > > --- a/arch/x86/pci/i386.c > > +++ b/arch/x86/pci/i386.c > > @@ -59,7 +59,7 @@ static struct pcibios_fwaddrmap *pcibios_fwaddrmap_lookup(struct pci_dev *dev) > > { > > struct pcibios_fwaddrmap *map; > > > > - WARN_ON_SMP(!spin_is_locked(&pcibios_fwaddrmap_lock)); > > + lockdep_assert_held(&pcibios_fwaddrmap_lock); > > > > list_for_each_entry(map, &pcibios_fwaddrmappings, list) > > if (map->dev == dev) > > -- > > 2.19.0 > >
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