Thanks Stephen for explaining the background of this patch. On Fri, 11 May 2012 00:34:40 +0200 Stephen Warren <swarren@xxxxxxxxxxxxx> wrote: > On 05/10/2012 04:28 PM, Greg Kroah-Hartman wrote: > > On Thu, May 10, 2012 at 02:00:48PM -0600, Stephen Warren wrote: > >> On 05/10/2012 12:16 PM, Greg Kroah-Hartman wrote: > >>> On Thu, May 10, 2012 at 09:59:15AM -0600, Stephen Warren wrote: > >>>> On 05/10/2012 08:11 AM, Greg Kroah-Hartman wrote: > >>>>> On Thu, May 10, 2012 at 10:35:02AM +0300, Hiroshi DOYU wrote: > >>>>>> driver_find_device() can be called with an unregistered driver. ... > > Can someone resend this to me, with the information above in the > > changelog comment, and I'll be glad to apply it? Again, I need to know > > if this is needed for 3.4 or it can wait for 3.5? > > I'll let Hiroshi do that. Greg, here's the update patch with the above explanation. Please take this one if the following explanation makes sense. >From d7cf9b53d3bbcce75ae55a9eed03c7e091529e3d Mon Sep 17 00:00:00 2001 From: Hiroshi DOYU <hdoyu@xxxxxxxxxx> Date: Wed, 9 May 2012 14:21:03 +0300 Subject: [PATCH 1/1] Driver Core: don't oops with unregistered driver in driver_find_device() driver_find_device() can be called with an unregistered driver. Need to check driver_private to see if it's populated or not, especially under deferrable probe. In the case that there are 2 drivers, one depends on the other. With -EPROBE_DEFER, two drivers can use deferred probe to ensure that their relative probe order doesn't matter. If dependee driver is probed first, then the dependant's driver_find_device('dependee') succeeds. If the dependant is probed first, then the dependant's driver_find_device('dependee') should return NULL, and the dependant should get -EPROBE_DEFER. driver_find_device() needs to return NULL if it's not populated. Signed-off-by: Hiroshi DOYU <hdoyu@xxxxxxxxxx> --- In [PATCHv5 2/3] ARM: tegra: Add SMMU enabler in AHB: http://article.gmane.org/gmane.linux.ports.tegra/4658 "tegra_ahb_driver" may not be populated when it's called. For more SMMU/AHB specific discussion, refer to the following thread: https://lkml.org/lkml/2012/5/10/21 --- drivers/base/driver.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/base/driver.c b/drivers/base/driver.c index 3ec3896..207c27d 100644 --- a/drivers/base/driver.c +++ b/drivers/base/driver.c @@ -80,7 +80,7 @@ struct device *driver_find_device(struct device_driver *drv, struct klist_iter i; struct device *dev; - if (!drv) + if (!drv || !drv->p) return NULL; klist_iter_init_node(&drv->p->klist_devices, &i, -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html