[PATCH] of/irq: Fix device_node refcount in of_irq_parse_raw()

Rob Herring robherring2 at gmail.com
Mon Dec 30 13:42:21 EST 2013


On Sun, Dec 29, 2013 at 8:37 PM, Benjamin Herrenschmidt <
benh at kernel.crashing.org> wrote:

> On Tue, 2013-12-17 at 18:32 +0100, Cédric Le Goater wrote:
> > Commit 2361613206e6, "of/irq: Refactor interrupt-map parsing" changed
> > the refcount on the device_node causing an error in of_node_put():
>
> Grant, Thierry, this is a regression, please send to Linus ASAP...
>
>
I'm working on doing that right this moment.

Rob


> Cheers,
> Ben.
>
> > ERROR: Bad of_node_put() on /pci at 800000020000000
> > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.13.0-rc3-dirty #2
> > Call Trace:
> > [c00000003e403500] [c0000000000144fc] .show_stack+0x7c/0x1f0 (unreliable)
> > [c00000003e4035d0] [c00000000070f250] .dump_stack+0x88/0xb4
> > [c00000003e403650] [c0000000005e8768] .of_node_release+0xd8/0xf0
> > [c00000003e4036e0] [c0000000005eeafc] .of_irq_parse_one+0x10c/0x280
> > [c00000003e4037a0] [c0000000005efd4c] .of_irq_parse_pci+0x3c/0x1d0
> > [c00000003e403840] [c000000000038240] .pcibios_setup_device+0xa0/0x2e0
> > [c00000003e403910] [c0000000000398f0]
> .pcibios_setup_bus_devices+0x60/0xd0
> > [c00000003e403990] [c00000000003b3a4] .__of_scan_bus+0x1a4/0x2b0
> > [c00000003e403a80] [c00000000003a62c] .pcibios_scan_phb+0x30c/0x410
> > [c00000003e403b60] [c0000000009fe430] .pcibios_init+0x7c/0xd4
> >
> > This patch adjusts the refcount in the walk of the interrupt tree.
> > When a match is found, there is no need to increase the refcount
> > on 'out_irq->np' as 'newpar' is already holding a ref. The refcount
> > balance between 'ipar' and 'newpar' is maintained in the skiplevel:
> > goto label.
> >
> > This patch also removes the usage of the device_node variable 'old'
> > which seems useless after the latest changes.
> >
> > Signed-off-by: Cédric Le Goater <clg at fr.ibm.com>
> > ---
> >
> > This patch was tested on powerpc, pseries and powernv. This is a
> > new area for me so I might have missed a path. Please take a look.
> >
> > We could now introduce an helper routine to look for #address-cells in
> > of_irq_parse_raw(). This can be the subject of another patch.
> >
> > Thanks,
> >
> > C.
> >
> >  drivers/of/irq.c |    5 +----
> >  1 file changed, 1 insertion(+), 4 deletions(-)
> >
> > diff --git a/drivers/of/irq.c b/drivers/of/irq.c
> > index 786b0b47fae4..27212402c532 100644
> > --- a/drivers/of/irq.c
> > +++ b/drivers/of/irq.c
> > @@ -165,7 +165,6 @@ int of_irq_parse_raw(const __be32 *addr, struct
> of_phandle_args *out_irq)
> >               if (of_get_property(ipar, "interrupt-controller", NULL) !=
> >                               NULL) {
> >                       pr_debug(" -> got it !\n");
> > -                     of_node_put(old);
> >                       return 0;
> >               }
> >
> > @@ -250,8 +249,7 @@ int of_irq_parse_raw(const __be32 *addr, struct
> of_phandle_args *out_irq)
> >                * Successfully parsed an interrrupt-map translation; copy
> new
> >                * interrupt specifier into the out_irq structure
> >                */
> > -             of_node_put(out_irq->np);
> > -             out_irq->np = of_node_get(newpar);
> > +             out_irq->np = newpar;
> >
> >               match_array = imap - newaddrsize - newintsize;
> >               for (i = 0; i < newintsize; i++)
> > @@ -268,7 +266,6 @@ int of_irq_parse_raw(const __be32 *addr, struct
> of_phandle_args *out_irq)
> >       }
> >   fail:
> >       of_node_put(ipar);
> > -     of_node_put(out_irq->np);
> >       of_node_put(newpar);
> >
> >       return -EINVAL;
>
>
> --
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