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Date: Thu, 28 Jun 2007 10:47:03 +0200
From: Anders Blomdell <anders.blomdell@control.lth.se>
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To: Marcel Holtmann <marcel@holtmann.org>
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Subject: Re: [PATCH] Documentation/firmware_class/firmware_sample_driver.c
References: <46827B20.6000501@control.lth.se> <1182966569.9499.1.camel@aeonflux.holtmann.net>
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Marcel Holtmann wrote:
> Hi Anders,
> 
>> Signed-off-by: Anders Blomdell <anders.blomdell@control.lth.se>
>>
>> Minor modifications to make the example load and unload without Oops
>>
>> This is what unpatched version generates with 2.6.21.3
>>
>> kernel: Oops: 0000 [#2]
>> ...
>> kernel: Call Trace:
>> kernel:  [<c04ae541>] sysfs_create_dir+0x49/0x63
>> kernel:  [<c04e76ae>] kobject_shadow_add+0xd5/0x17d
>> kernel:  [<c04e7908>] kobject_set_name+0x2b/0x92
>> kernel:  [<c0556444>] device_add+0x9a/0x58e
>> kernel:  [<c0620b65>] klist_init+0x23/0x2e
>> kernel:  [<c055bfee>] _request_firmware+0x116/0x29f
>> kernel:  [<c062149f>] wait_for_completion+0x8b/0x93
>> kernel:  [<c055c20b>] request_firmware+0xf/0x11
>> kernel:  [<e09420d9>] sample_init+0x59/0xc0 [firmware_sample_driver]
>> kernel:  [<c0446c92>] sys_init_module+0x16b7/0x17ee
>> kernel:  [<c04294de>] printk+0x0/0x1f
>> kernel:  [<c0488436>] mntput_no_expire+0x11/0x6e
>> kernel:  [<c0404fa8>] syscall_call+0x7/0xb
>>
>>
>>
>> diff -u Documentation/firmware_class/firmware_sample_driver.c
>> /tmp/fw/firmware_sample_driver.c
>> --- Documentation/firmware_class/firmware_sample_driver.c       2007-05-24
>> 23:22:47.000000000 +0200
>> +++ /tmp/fw/firmware_sample_driver.c    2007-06-27 16:51:16.000000000 +0200
>> @@ -15,11 +15,16 @@
>>
>>  #include "linux/firmware.h"
>>
>> +static void ghost_release(struct device *dev)
>> +{
>> +       printk(KERN_DEBUG "firmware_sample_driver: ghost_release\n");
>> +}
>> +
> 
> I know it is a sample driver, but you can't do that. You have to
> allocate the device and then free it here.
Are you sure about this? The code in the example looks very similar to the code
in "Linux Device Drivers" 3rd edition, p 382.

Regards

Anders Blomdell

-- 
Anders Blomdell                  Email: anders.blomdell@control.lth.se
Department of Automatic Control
Lund University                  Phone:    +46 46 222 4625
P.O. Box 118                     Fax:      +46 46 138118
SE-221 00 Lund, Sweden
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