linux-kernel - Re: [PATCH v12 06/13] task_isolation: support PR_TASK_ISOLATION

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Message-ID: <20160518134406.GI3193@twins.programming.kicks-ass.net>
Date:	Wed, 18 May 2016 15:44:06 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Chris Metcalf <cmetcalf@...lanox.com>
Cc:	Gilad Ben Yossef <giladb@...hip.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>, Tejun Heo <tj@...nel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Christoph Lameter <cl@...ux.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Andy Lutomirski <luto@...capital.net>,
	linux-doc@...r.kernel.org, linux-api@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v12 06/13] task_isolation: support
 PR_TASK_ISOLATION_STRICT mode

On Tue, Apr 05, 2016 at 01:38:35PM -0400, Chris Metcalf wrote:
> +void task_isolation_interrupt(struct task_struct *task, const char *buf)
> +{
> +	siginfo_t info = {};
> +	int sig;
> +
> +	pr_warn("%s/%d: task_isolation strict mode violated by %s\n",
> +		task->comm, task->pid, buf);
> +

So the function name suggests this is called for interrupts, except its
purpose is to deliver a signal.

Now, in case of exceptions the violation isn't necessarily _by_ the task
itself. You might want to change that to report the exception
type/number instead of the affected task.

> +	/* Get the signal number to use. */
> +	sig = PR_TASK_ISOLATION_GET_SIG(task->task_isolation_flags);
> +	if (sig == 0)
> +		sig = SIGKILL;
> +	info.si_signo = sig;
> +
> +	/*
> +	 * Turn off task isolation mode entirely to avoid spamming
> +	 * the process with signals.  It can re-enable task isolation
> +	 * mode in the signal handler if it wants to.
> +	 */
> +	task_isolation_set_flags(task, 0);
> +
> +	send_sig_info(sig, &info, task);
> +}