Block driver design issue

From: LA Walsh (
Date: Mon Feb 12 2001 - 12:16:02 EST

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?


L A Walsh                    | Trust Technology, Core Linux, SGI                      | Voice: (650) 933-5338
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This archive was generated by hypermail 2b29 : Thu Feb 15 2001 - 21:00:19 EST