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SubjectRe: sparse annotation question
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David Miller (on Tue, 11 Jul 2006 23:14:09 -0700 (PDT)) wrote:
>From: Keith Owens <kaos@ocs.com.au>
>Date: Wed, 12 Jul 2006 15:47:03 +1000
>
>> func (long regno, unsigned long *contents)
>> {
>> unsigned long i, *bsp;
>> mm_segment_t old_fs;
>> bsp = <expression involving only kernel variables>;
>> old_fs = set_fs(KERNEL_DS);
>> for (i = 0; i < (regno - 32); ++i)
>> bsp = ia64_rse_skip_regs(bsp, 1);
>> put_user(*contents, bsp);
>> set_fs(old_fs);
>> }
>>
>> sparse is complaining that the second parameter to put_user() is not
>> marked as __user. How do I tell sparse to ignore this case? Marking
>> bsp as __user does not work, sparse then complains about incorrect type
>> in assignment (different address spaces).
>
>Since, in this case, you "know what you are doing" you can force the
>matter by using the __force keyword as well as __user.

I tried various combinations of __force, but kept getting this:

warning: incorrect type in argument 1 (different address spaces)
expected unsigned long *addr
got unsigned long [noderef] [force] *[addressable] bsp<asn:1>

What finally worked was

unsigned long i, *bsp, __user *ubsp;
...
ubsp = (unsigned long __user *) bsp;
put_user(*contents, ubsp);

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