linux-kernel - Re: [Patch 3/3] HW-BKPT: Enable/disable the breakpoints when still registered

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Date:	Thu, 27 Aug 2009 11:25:08 +0530
From:	Ananth N Mavinakayanahalli <ananth@...ibm.com>
To:	"K.Prasad" <prasad@...ux.vnet.ibm.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	Alan Stern <stern@...land.harvard.edu>
Subject: Re: [Patch 3/3] HW-BKPT: Enable/disable the breakpoints when still
	registered

On Thu, Aug 27, 2009 at 01:45:06AM +0530, K.Prasad wrote:

...

>  struct hw_breakpoint {
> +	/*
> +	 * Denotes if a breakpoint is currently enabled in physical debug
> +	 * registers. Not to be set directly by the end-user. Must be
> +	 * operated through enable_hw_breakpoint() API only.
> +	 */
> +	unsigned int enabled;

bool?

...

> +void enable_hw_breakpoint(struct hw_breakpoint *bp, struct task_struct *tsk,
> +							unsigned int enabled)
> +{
> +	int i;
> +	struct thread_struct *thread = &(tsk->thread);
> +
> +	spin_lock_bh(&hw_breakpoint_lock);
> +
> +	bp->enabled = enabled;
> +	/* Enable/Disable the kernel-space breakpoint */
> +	if (!tsk) {
> +		if (cpumask_test_cpu(smp_processor_id(), bp->cpumask))
> +			arch_update_kernel_hw_breakpoint(NULL);
> +		smp_call_function_many(bp->cpumask,
> +				arch_update_kernel_hw_breakpoint, NULL, 1);
> +		goto out;
> +	}
> +
> +	/* Enable/disable the user-space breakpoint */
> +	for (i = 0; i < hbp_kernel_pos; i++) {
> +		if (thread->hbp[i] != bp)
> +			continue;
> +		arch_update_user_hw_breakpoint(i, tsk);
> +		if (tsk == current)
> +			arch_install_thread_hw_breakpoint(tsk);
> +		break;
> +	}
> +out:
> +	spin_unlock_bh(&hw_breakpoint_lock);
> +}
> +EXPORT_SYMBOL_GPL(enable_hw_breakpoint);

Not sure if its cleaner to have enable_hw_breakpoint() and
disable_hw_breakpoint() rather than one overloaded call.

Ananth
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