linux-kernel - Re: [patch 00/11] Hardware Breakpoint interfaces

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Message-ID: <Pine.LNX.4.44L0.0903101019570.2962-100000@iolanthe.rowland.org>
Date:	Tue, 10 Mar 2009 10:24:24 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Ingo Molnar <mingo@...e.hu>
cc:	prasad@...ux.vnet.ibm.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Roland McGrath <roland@...hat.com>
Subject: Re: [patch 00/11] Hardware Breakpoint interfaces

On Tue, 10 Mar 2009, Ingo Molnar wrote:

> 
> There's also a few checkpatch warnings that need to be 
> addressed:
> 
> ERROR: do not use assignment in if condition
> #1084: FILE: arch/x86/kernel/ptrace.c:581:
> +	else if ((thbi = alloc_thread_hw_breakpoint(tsk)) == 
> NULL)

Changing this to remove the assignment from within the "if" condition 
would make the code less readable, not more.  It's part of a long 
series of tests; in schematic form:

	if (n == 4 || n == 5)
...
	else if (n == 6) {
...
	}
	else if (!tsk->thread.hw_breakpoint_info && val == 0)
...
	else if ((thbi = alloc_thread_hw_breakpoint(tsk)) == NULL)
...
	else if (n < HB_NUM) {
...
	}
	else
...

If you can suggest a way to change the code without making it worse,
I'm sure Prasad will be happy to adopt it.

Alan Stern

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