From: Peter Zijlstra <peterz@infradead.org>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>, Tejun Heo <tj@kernel.org>,
"David S . Miller" <davem@davemloft.net>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH 07/14] x86: Use lockdep to assert IRQs are disabled/enabled
Date: Sun, 22 Oct 2017 11:20:25 +0200 [thread overview]
Message-ID: <20171022092025.GJ6524@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <1508460971-8731-8-git-send-email-frederic@kernel.org>
On Fri, Oct 20, 2017 at 02:56:04AM +0200, Frederic Weisbecker wrote:
> diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
> index 03505ff..b4f3a55 100644
> --- a/arch/x86/entry/common.c
> +++ b/arch/x86/entry/common.c
> @@ -186,7 +186,7 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs)
>
> addr_limit_user_check();
>
> - if (IS_ENABLED(CONFIG_PROVE_LOCKING) && WARN_ON(!irqs_disabled()))
> + if (!lockdep_assert_irqs_disabled())
> local_irq_disable();
>
> lockdep_sys_exit();
So this is the only site that ever uses the return value; and for this
you've chosen the wrong value for !CONFIG_PROVE_LOCKING (namely 1),
resulting in an unconditional CLI here for !lockdep kernels.
How about we replace that whole thing with a simple:
lockdep_assert_irqs_disabled();
And leave it at that, allowing us to remove the return value thing
entirely.
The whole if !disabled, disable logic is uber paranoid programming, but
I don't think we've ever seen that WARN trigger, and if it does (and
then burns the kernel) we at least know wtf happend.
next prev parent reply other threads:[~2017-10-22 9:20 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-20 0:55 [PATCH 00/14] lockdep: Add lightweight IRQs disabled/enabled check Frederic Weisbecker
2017-10-20 0:55 ` [PATCH 01/14] lockdep: Add IRQs disabled/enabled assertion Frederic Weisbecker
2017-10-20 0:55 ` [PATCH 02/14] irq: Use lockdep to assert IRQs are disabled/enabled Frederic Weisbecker
2017-10-20 0:56 ` [PATCH 03/14] workqueue: " Frederic Weisbecker
2017-10-21 15:39 ` Tejun Heo
2017-10-20 0:56 ` [PATCH 04/14] nohz: " Frederic Weisbecker
2017-10-20 0:56 ` [PATCH 05/14] hrtimer: " Frederic Weisbecker
2017-10-20 0:56 ` [PATCH 06/14] smp: " Frederic Weisbecker
2017-10-20 0:56 ` [PATCH 07/14] x86: " Frederic Weisbecker
2017-10-22 9:20 ` Peter Zijlstra [this message]
2017-11-03 14:25 ` Frederic Weisbecker
2017-10-20 0:56 ` [PATCH 08/14] perf: " Frederic Weisbecker
2017-10-20 0:56 ` [PATCH 09/14] irq/timings: " Frederic Weisbecker
2017-10-20 0:56 ` [PATCH 10/14] irq_work: " Frederic Weisbecker
2017-10-20 0:56 ` [PATCH 11/14] sched: " Frederic Weisbecker
2017-10-20 0:56 ` [PATCH 12/14] posix-cpu-timers: " Frederic Weisbecker
2017-10-20 0:56 ` [PATCH 13/14] netpoll: " Frederic Weisbecker
2017-10-20 0:56 ` [PATCH 14/14] rcu: " Frederic Weisbecker
2017-10-21 21:36 ` Paul E. McKenney
2017-11-06 15:01 [GIT PULL] lockdep: Add lightweight IRQs disabled/enabled check v2 Frederic Weisbecker
2017-11-06 15:01 ` [PATCH 07/14] x86: Use lockdep to assert IRQs are disabled/enabled Frederic Weisbecker
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