On Thu, 26 Feb 2009, Stefan Richter wrote: > > Alas I have no Linux box at hand before Saturday. I wonder, was > ieee1394_bus_type not yet registered (i.e. ieee1394's ieee1394_init() not yet > called) at the moment when fdtv_init is executed? > > Or what else could have been the NULL pointer dereference in driver_find? Afaik, the only way that NULL pointer dereference can happen is if struct kobject *k = kset_find_obj(bus->p->drivers_kset, name); gets a NULL pointer exception either because of a NULL "bus" pointer as the argument, or if "bus->p" is NULL. And in this case, it's the latter. The Code: decode shows the whole function in this case: 1c: 55 push %rbp 1d: 89 e5 mov %esp,%ebp 1f: e8 34 5f c8 ff callq 0xffffffffffc85f58 24: 89 c1 mov %eax,%ecx 26: 8b 42 38 mov 0x38(%rdx),%eax 29: 89 ca mov %ecx,%edx 2b:* 8b 40 54 mov 0x54(%rax),%eax <-- trapping instruction 2e: e8 6c 48 f9 ff callq 0xfffffffffff9489f 33: 31 d2 xor %edx,%edx 35: 85 c0 test %eax,%eax 37: 74 03 je 0x3c 39: 8b 50 6c mov 0x6c(%rax),%edx 3c: 5d pop %rbp 3d: 89 d0 mov %edx,%eax 3f: c3 retq and that first "callq" seems to be due to Ingo having function tracing on, while the second callq would have been that 'kset_find_obj()' thing. So it does look like "&ieee1394_bus_type" has simply not been initialized yet. It looks like ieee1394_init() is called too late. Two choices that I can see: - do the ieee1394_init() as a fs_initcall(), earlier - move drivers/ieee1394 linking up to before drivers/media but I suspect that drivers/media wants to be early, in order to do the _media_ layer initialization early. Does this work? Linus --- drivers/ieee1394/ieee1394_core.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/ieee1394/ieee1394_core.c b/drivers/ieee1394/ieee1394_core.c index 1028e72..8723380 100644 --- a/drivers/ieee1394/ieee1394_core.c +++ b/drivers/ieee1394/ieee1394_core.c @@ -1275,7 +1275,7 @@ static void __exit ieee1394_cleanup(void) unregister_chrdev_region(IEEE1394_CORE_DEV, 256); } -module_init(ieee1394_init); +fs_initcall(ieee1394_init); module_exit(ieee1394_cleanup); /* Exported symbols */ -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
