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Date: Wed, 18 May 2016 15:44:06 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Gilad Ben Yossef <giladb@ezchip.com>, Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Rik van Riel <riel@redhat.com>, Tejun Heo <tj@kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Christoph Lameter <cl@linux.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Andy Lutomirski <luto@amacapital.net>, linux-doc@vger.kernel.org,
        linux-api@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v12 06/13] task_isolation: support
 PR_TASK_ISOLATION_STRICT mode
Message-ID: <20160518134406.GI3193@twins.programming.kicks-ass.net>
References: <1459877922-15512-1-git-send-email-cmetcalf@mellanox.com>
 <1459877922-15512-7-git-send-email-cmetcalf@mellanox.com>
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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);
> +}