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Date: Thu, 16 Nov 2017 17:18:15 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        Andy Lutomirski <luto@amacapital.net>,
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        linux-api@vger.kernel.org, Paul Turner <pjt@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Russell King <linux@arm.linux.org.uk>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H . Peter Anvin" <hpa@zytor.com>, Andrew Hunter <ahh@google.com>,
        Andi Kleen <andi@firstfloor.org>, Chris Lameter <cl@linux.com>,
        Ben Maurer <bmaurer@fb.com>, Steven Rostedt <rostedt@goodmis.org>,
        Josh Triplett <josh@joshtriplett.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>
Subject: Re: [RFC PATCH v11 for 4.15 01/24] Restartable sequences system call
Message-ID: <20171116161815.dg4hi2z35rkh4u4s@hirez.programming.kicks-ass.net>
References: <20171114200414.2188-1-mathieu.desnoyers@efficios.com>
 <20171114200414.2188-2-mathieu.desnoyers@efficios.com>
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On Tue, Nov 14, 2017 at 03:03:51PM -0500, Mathieu Desnoyers wrote:
> @@ -977,6 +978,13 @@ struct task_struct {
>  	unsigned long			numa_pages_migrated;
>  #endif /* CONFIG_NUMA_BALANCING */
>  
> +#ifdef CONFIG_RSEQ
> +	struct rseq __user *rseq;
> +	u32 rseq_len;
> +	u32 rseq_sig;
> +	bool rseq_preempt, rseq_signal, rseq_migrate;

No bool please. Use something that has a defined size in ILP32/LP64.
_Bool makes it absolutely impossible to speculate on structure layout
across architectures.

> +#endif
> +
>  	struct tlbflush_unmap_batch	tlb_ubc;
>  
>  	struct rcu_head			rcu;