From: nicolas saenz julienne <nsaenz@kernel.org>
To: Frederic Weisbecker <frederic@kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Phil Auld <pauld@redhat.com>, Alex Belits <abelits@marvell.com>,
Xiongfeng Wang <wangxiongfeng2@huawei.com>,
Neeraj Upadhyay <quic_neeraju@quicinc.com>,
Thomas Gleixner <tglx@linutronix.de>,
Yu Liao <liaoyu15@huawei.com>, Boqun Feng <boqun.feng@gmail.com>,
"Paul E . McKenney" <paulmck@kernel.org>,
Marcelo Tosatti <mtosatti@redhat.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Uladzislau Rezki <uladzislau.rezki@sony.com>,
Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [PATCH 20/21] context_tracking: Convert state to atomic_t
Date: Wed, 18 May 2022 17:09:55 +0200 [thread overview]
Message-ID: <372364b33b8d4b93908c3822e18f7d295de2ede9.camel@kernel.org> (raw)
In-Reply-To: <20220503100051.2799723-21-frederic@kernel.org>
On Tue, 2022-05-03 at 12:00 +0200, Frederic Weisbecker wrote:
[...]
> +/**
> + * ct_state() - return the current context tracking state if known
> + *
> + * Returns the current cpu's context tracking state if context tracking
> + * is enabled. If context tracking is disabled, returns
> + * CONTEXT_DISABLED. This should be used primarily for debugging.
> + */
> +static __always_inline int ct_state(void)
> +{
> + int ret;
> +
> + if (!context_tracking_enabled())
> + return CONTEXT_DISABLED;
> +
> + preempt_disable();
> + ret = __ct_state();
> + preempt_enable();
> +
> + return ret;
> +}
> +
I can't see any use for this function with preemption enabled. You can't trust
the data due to CPU migration and it could be a source of bugs in the future.
Wouldn't it make more sense to move the burden into the callers? They all DTRT,
plus, this_cpu_ptr() will spew warnings if someone shows up and doesn't comply.
Regards,
--
Nicolás Sáenz
next prev parent reply other threads:[~2022-05-18 15:10 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-03 10:00 [PATCH 00/21] rcu/context-tracking: Merge RCU eqs-dynticks counter to context tracking v2 Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 01/21] context_tracking: Remove unused context_tracking_in_user() Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 02/21] rcu: Set rcu_idle_enter() as noinstr Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 03/21] rcu: Add a note about noinstr VS unsafe eqs functions Frederic Weisbecker
2022-05-19 14:48 ` Peter Zijlstra
2022-05-19 15:01 ` Frederic Weisbecker
2022-05-19 14:54 ` Peter Zijlstra
2022-05-19 15:26 ` Paul E. McKenney
2022-05-19 15:35 ` Frederic Weisbecker
2022-05-19 16:10 ` Paul E. McKenney
2022-05-19 15:00 ` Peter Zijlstra
2022-05-19 15:04 ` Frederic Weisbecker
2022-05-19 21:43 ` Peter Zijlstra
2022-05-03 10:00 ` [PATCH 04/21] context_tracking: Add a note about noinstr VS unsafe context tracking functions Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 05/21] context_tracking: Rename __context_tracking_enter/exit() to __ct_user_enter/exit() Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 06/21] context_tracking: Rename context_tracking_user_enter/exit() to user_enter/exit_callable() Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 07/21] context_tracking: Rename context_tracking_enter/exit() to ct_user_enter/exit() Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 08/21] context_tracking: Rename context_tracking_cpu_set() to ct_cpu_track_user() Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 09/21] context_tracking: Split user tracking Kconfig Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 10/21] context_tracking: Take idle eqs entrypoints over RCU Frederic Weisbecker
2022-05-03 11:02 ` Mark Rutland
2022-05-03 11:42 ` Frederic Weisbecker
2022-05-03 13:33 ` Mark Rutland
2022-05-03 10:00 ` [PATCH 11/21] context_tracking: Take IRQ " Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 12/21] context_tracking: Take NMI " Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 13/21] rcu/context-tracking: Remove rcu_irq_enter/exit() Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 14/21] rcu/context_tracking: Move dynticks counter to context tracking Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 15/21] rcu/context_tracking: Move dynticks_nesting " Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 16/21] rcu/context_tracking: Move dynticks_nmi_nesting " Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 17/21] rcu/context-tracking: Move deferred nocb resched " Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 18/21] rcu/context-tracking: Move RCU-dynticks internal functions to context_tracking Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 19/21] rcu/context-tracking: Remove unused and/or unecessary middle functions Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 20/21] context_tracking: Convert state to atomic_t Frederic Weisbecker
2022-05-18 15:09 ` nicolas saenz julienne [this message]
2022-05-19 14:37 ` Frederic Weisbecker
2022-05-23 11:59 ` nicolas saenz julienne
2022-05-03 10:00 ` [PATCH 21/21] rcu/context_tracking: Merge dynticks counter and context tracking states Frederic Weisbecker
2022-05-18 15:31 ` nicolas saenz julienne
2022-05-19 15:06 ` Frederic Weisbecker
2022-05-18 15:33 ` [PATCH 00/21] rcu/context-tracking: Merge RCU eqs-dynticks counter to context tracking v2 Nicolas Saenz Julienne
2022-05-19 15:07 ` Frederic Weisbecker
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