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From: peterz@infradead.org
To: Peter Oskolkov <posk@google.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	linux-kernel@vger.kernel.org, Paul Turner <pjt@google.com>,
	Chris Kennelly <ckennelly@google.com>,
	Peter Oskolkov <posk@posk.io>
Subject: Re: [PATCH 1/2] membarrier: add MEMBARRIER_CMD_PRIVATE_RESTART_RSEQ_ON_CPU
Date: Thu, 6 Aug 2020 15:48:28 +0200	[thread overview]
Message-ID: <20200806134828.GA165568@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200806000859.160882-1-posk@google.com>

On Wed, Aug 05, 2020 at 05:08:58PM -0700, Peter Oskolkov wrote:

Thanks for the Cc!

> + * @MEMBARRIER_CMD_PRIVATE_RESTART_RSEQ_ON_CPU:
> + *                          If a thread belonging to the current process
> + *                          is currently in an RSEQ critical section on the
> + *                          CPU identified by flags parameter, restart it.
> + *                          @flags: if @flags >= 0, identifies the CPU to
> + *                                  restart RSEQ CS on; if == -1, restarts
> + *                                  RSEQ CSs on all CPUs.

> +	} else if (cpu_id == -1) {
> +		on_each_cpu(membarrier_rseq_ipi,
> +			    current->group_leader, true);

This is an unpriv IPI the world. That's a big no-no.

Double so because all you want to target is the current process, which
you're defining as CLONE_THREAD, where the rest of this file uses
CLONE_VM to define a process.

  parent reply	other threads:[~2020-08-06 17:27 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-06  0:08 [PATCH 1/2] membarrier: add MEMBARRIER_CMD_PRIVATE_RESTART_RSEQ_ON_CPU Peter Oskolkov
2020-08-06  0:08 ` [PATCH 2/2] selftests/rseq: test MEMBARRIER_CMD_PRIVATE_RESTART_RSEQ_ON_CPU Peter Oskolkov
2020-08-06 13:48 ` peterz [this message]
2020-08-06 17:07   ` [PATCH 1/2] membarrier: add MEMBARRIER_CMD_PRIVATE_RESTART_RSEQ_ON_CPU Peter Oskolkov
2020-08-06 17:37     ` Mathieu Desnoyers
2020-08-07 17:48       ` Peter Oskolkov
2020-08-07 18:07         ` Mathieu Desnoyers
2020-08-07 19:02           ` peterz

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