Block driver design issue

LA Walsh (law@sgi.com)
Mon, 12 Feb 2001 09:16:02 -0800


I have a block driver I inherited that I working on that has a problem and
was wondering for cleaner solutions.

The driver can accept written characters from either userspace programs or from
the kernel. From userspace it uses sys_write. That in turn calls block_write.
There's almost 100 lines of duplicated code in a copy of the block_write
code in the driver "block_writek" as well as duplicate code in audit_write vs. audit_writek.
The only difference being down in block_write at the "copy_from_user(p,buf,chars); "
which becomes a "memcpy(p,buf,chars)" in the "block_writek" version.

I find this duplication of code to be inefficient. Is there a way to dummy up the
the 'buf' address so that the "copy_from_user" will copy the buffer from kernel space?
My assumption is that it wouldn't "just work" (which may also be an invalid assumption).

Suggestions? Abuse?

Thanks!
-linda

-- 
L A Walsh                    | Trust Technology, Core Linux, SGI
law@sgi.com                      | Voice: (650) 933-5338
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