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>Kernel Cantrips</H1
><P
> Some favorites from browsing the source. Feel free to add to this
list.
</P
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> <TT
CLASS="FILENAME"
>include/linux/brlock.h:</TT
>
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>extern inline void br_read_lock (enum brlock_indices idx)
{
/*
* This causes a link-time bug message if an
* invalid index is used:
*/
if (idx >= __BR_END)
__br_lock_usage_bug();
read_lock(&__brlock_array[smp_processor_id()][idx]);
}
</PRE
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> <TT
CLASS="FILENAME"
>include/linux/fs.h</TT
>:
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>/*
* Kernel pointers have redundant information, so we can use a
* scheme where we can return either an error code or a dentry
* pointer with the same return value.
*
* This should be a per-architecture thing, to allow different
* error and pointer decisions.
*/
#define ERR_PTR(err) ((void *)((long)(err)))
#define PTR_ERR(ptr) ((long)(ptr))
#define IS_ERR(ptr) ((unsigned long)(ptr) > (unsigned long)(-1000))</PRE
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> <TT
CLASS="FILENAME"
>include/asm-i386/uaccess.h:</TT
>
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>#define copy_to_user(to,from,n) \
(__builtin_constant_p(n) ? \
__constant_copy_to_user((to),(from),(n)) : \
__generic_copy_to_user((to),(from),(n)))
</PRE
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> <TT
CLASS="FILENAME"
>arch/sparc/kernel/head.S:</TT
>
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>/*
* Sun people can't spell worth damn. "compatability" indeed.
* At least we *know* we can't spell, and use a spell-checker.
*/
/* Uh, actually Linus it is I who cannot spell. Too much murky
* Sparc assembly will do this to ya.
*/
C_LABEL(cputypvar):
.asciz "compatability"
/* Tested on SS-5, SS-10. Probably someone at Sun applied a spell-checker. */
.align 4
C_LABEL(cputypvar_sun4m):
.asciz "compatible"
</PRE
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><P
> <TT
CLASS="FILENAME"
>arch/sparc/lib/checksum.S:</TT
>
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><PRE
CLASS="PROGRAMLISTING"
> /* Sun, you just can't beat me, you just can't. Stop trying,
* give up. I'm serious, I am going to kick the living shit
* out of you, game over, lights out.
*/
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