folks,
Im trying to update an existing kernel char-driver to use 2.6 cdev api,
thus far Ive failed..
Ive cut my patch down to a single, fairly bare version of scullc example
from LDD-3,
which applies to drivers/char/scx200_gpio. It compiles ok, but does
this when I
access one of the pins.
Badness in kref_get at lib/kref.c:32
[<c01b918a>] kref_get+0x2a/0x30
[<c01b88f2>] kobject_get+0x12/0x20
[<c014bc80>] cdev_get+0x20/0x50
[<c014bd01>] chrdev_open+0x21/0x120
[<c0143674>] dentry_open+0x154/0x1c0
[<c0143510>] filp_open+0x50/0x60
[<c0143805>] sys_open+0x35/0x70
[<c01026f9>] syscall_call+0x7/0xb
30 void kref_get(struct kref *kref)
31 {
32 WARN_ON(!atomic_read(&kref->refcount));
33 atomic_inc(&kref->refcount);
34 }
the object-dump tells me nothing.
00000010 <kref_get>:
10: 53 push %ebx
11: 8b 5c 24 08 mov 0x8(%esp),%ebx
15: 8b 03 mov (%ebx),%eax
17: 85 c0 test %eax,%eax
19: 74 04 je 1f <kref_get+0xf>
1b: ff 03 incl (%ebx)
1d: 5b pop %ebx
1e: c3 ret
1f: 6a 20 push $0x20
21: 68 00 00 00 00 push $0x0
26: 68 00 00 00 00 push $0x0
2b: 68 0b 00 00 00 push $0xb
30: e8 fc ff ff ff call 31 <kref_get+0x21>
35: e8 fc ff ff ff call 36 <kref_get+0x26>
3a: 83 c4 10 add $0x10,%esp
3d: eb dc jmp 1b <kref_get+0xb>
3f: 90 nop
(btw is there a way to get objdump to give offsets relative to the labels,
the way theyre given above ? Its a pin to do hex arithmetic to go from
file-offset to label offset)
One thing that gave me pause was the the fact that this driver is dependent
upon another module, (scx200) thats a pci-device. But since I dont know any
better/different, I figured Id try it.
Presuming that the pci-device driver is not updated either (a safe bet),
is that a potential (or definite?) source of problems like the one above ?
tia
jimc
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