From: "Paul E. McKenney" <paulmck@kernel.org>
To: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
"Theodore Y . Ts'o" <tytso@mit.edu>,
Matthew Wilcox <willy@infradead.org>,
Joel Fernandes <joel@joelfernandes.org>,
RCU <rcu@vger.kernel.org>,
Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: [PATCH 08/24] rcu/tree: Use static initializer for krc.lock
Date: Fri, 1 May 2020 14:17:03 -0700 [thread overview]
Message-ID: <20200501211703.GC7560@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <20200428205903.61704-9-urezki@gmail.com>
On Tue, Apr 28, 2020 at 10:58:47PM +0200, Uladzislau Rezki (Sony) wrote:
> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>
> The per-CPU variable is initialized at runtime in
> kfree_rcu_batch_init(). This function is invoked before
> 'rcu_scheduler_active' is set to 'RCU_SCHEDULER_RUNNING'.
> After the initialisation, '->initialized' is to true.
>
> The raw_spin_lock is only acquired if '->initialized' is
> set to true. The worqueue item is only used if 'rcu_scheduler_active'
> set to RCU_SCHEDULER_RUNNING which happens after initialisation.
>
> Use a static initializer for krc.lock and remove the runtime
> initialisation of the lock. Since the lock can now be always
> acquired, remove the '->initialized' check.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> ---
> kernel/rcu/tree.c | 15 +++++++--------
> 1 file changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index bc6c2bc8fa32..89e9ca3f4e3e 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -2892,7 +2892,7 @@ struct kfree_rcu_cpu_work {
> * @lock: Synchronize access to this structure
> * @monitor_work: Promote @head to @head_free after KFREE_DRAIN_JIFFIES
> * @monitor_todo: Tracks whether a @monitor_work delayed work is pending
> - * @initialized: The @lock and @rcu_work fields have been initialized
> + * @initialized: The @rcu_work fields have been initialized
> *
> * This is a per-CPU structure. The reason that it is not included in
> * the rcu_data structure is to permit this code to be extracted from
> @@ -2912,7 +2912,9 @@ struct kfree_rcu_cpu {
> int count;
> };
>
> -static DEFINE_PER_CPU(struct kfree_rcu_cpu, krc);
> +static DEFINE_PER_CPU(struct kfree_rcu_cpu, krc) = {
> + .lock = __RAW_SPIN_LOCK_UNLOCKED(krc.lock),
> +};
>
> static __always_inline void
> debug_rcu_bhead_unqueue(struct kfree_rcu_bulk_data *bhead)
> @@ -2930,10 +2932,9 @@ krc_this_cpu_lock(unsigned long *flags)
> {
> struct kfree_rcu_cpu *krcp;
>
> - local_irq_save(*flags); // For safely calling this_cpu_ptr().
> + local_irq_save(*flags); /* For safely calling this_cpu_ptr(). */
And here as well. ;-)
Thanx, Paul
> krcp = this_cpu_ptr(&krc);
> - if (likely(krcp->initialized))
> - raw_spin_lock(&krcp->lock);
> + raw_spin_lock(&krcp->lock);
>
> return krcp;
> }
> @@ -2941,8 +2942,7 @@ krc_this_cpu_lock(unsigned long *flags)
> static inline void
> krc_this_cpu_unlock(struct kfree_rcu_cpu *krcp, unsigned long flags)
> {
> - if (likely(krcp->initialized))
> - raw_spin_unlock(&krcp->lock);
> + raw_spin_unlock(&krcp->lock);
> local_irq_restore(flags);
> }
>
> @@ -4168,7 +4168,6 @@ static void __init kfree_rcu_batch_init(void)
> for_each_possible_cpu(cpu) {
> struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
>
> - raw_spin_lock_init(&krcp->lock);
> for (i = 0; i < KFREE_N_BATCHES; i++) {
> INIT_RCU_WORK(&krcp->krw_arr[i].rcu_work, kfree_rcu_work);
> krcp->krw_arr[i].krcp = krcp;
> --
> 2.20.1
>
next prev parent reply other threads:[~2020-05-01 21:17 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-28 20:58 [PATCH 00/24] Introduce kvfree_rcu(1 or 2 arguments) Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 01/24] rcu/tree: Keep kfree_rcu() awake during lock contention Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 02/24] rcu/tree: Skip entry into the page allocator for PREEMPT_RT Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 03/24] rcu/tree: Use consistent style for comments Uladzislau Rezki (Sony)
2020-05-01 19:05 ` Paul E. McKenney
2020-05-01 20:52 ` Joe Perches
2020-05-03 23:44 ` Joel Fernandes
2020-05-04 0:23 ` Paul E. McKenney
2020-05-04 0:34 ` Joe Perches
2020-05-04 0:41 ` Joel Fernandes
2020-05-03 23:52 ` Joel Fernandes
2020-05-04 0:26 ` Paul E. McKenney
2020-05-04 0:39 ` Joel Fernandes
2020-04-28 20:58 ` [PATCH 04/24] rcu/tree: Repeat the monitor if any free channel is busy Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 05/24] rcu/tree: Simplify debug_objects handling Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 06/24] rcu/tree: Simplify KFREE_BULK_MAX_ENTR macro Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 07/24] rcu/tree: move locking/unlocking to separate functions Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 08/24] rcu/tree: Use static initializer for krc.lock Uladzislau Rezki (Sony)
2020-05-01 21:17 ` Paul E. McKenney [this message]
2020-05-04 12:10 ` Uladzislau Rezki
2020-04-28 20:58 ` [PATCH 09/24] rcu/tree: cache specified number of objects Uladzislau Rezki (Sony)
2020-05-01 21:27 ` Paul E. McKenney
2020-05-04 12:43 ` Uladzislau Rezki
2020-05-04 15:24 ` Paul E. McKenney
2020-05-04 17:48 ` Uladzislau Rezki
2020-05-04 18:07 ` Paul E. McKenney
2020-05-04 18:08 ` Joel Fernandes
2020-05-04 19:01 ` Paul E. McKenney
2020-05-04 19:37 ` Joel Fernandes
2020-05-04 19:51 ` Uladzislau Rezki
2020-05-04 20:15 ` joel
2020-05-04 20:16 ` Paul E. McKenney
2020-05-05 11:03 ` Uladzislau Rezki
2020-04-28 20:58 ` [PATCH 10/24] rcu/tree: add rcutree.rcu_min_cached_objs description Uladzislau Rezki (Sony)
2020-05-01 22:25 ` Paul E. McKenney
2020-05-04 12:44 ` Uladzislau Rezki
2020-04-28 20:58 ` [PATCH 11/24] rcu/tree: Maintain separate array for vmalloc ptrs Uladzislau Rezki (Sony)
2020-05-01 21:37 ` Paul E. McKenney
2020-05-03 23:42 ` Joel Fernandes
2020-05-04 0:20 ` Paul E. McKenney
2020-05-04 0:58 ` Joel Fernandes
2020-05-04 2:20 ` Paul E. McKenney
2020-05-04 14:25 ` Uladzislau Rezki
2020-04-28 20:58 ` [PATCH 12/24] rcu/tiny: support vmalloc in tiny-RCU Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 13/24] rcu: Rename rcu_invoke_kfree_callback/rcu_kfree_callback Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 14/24] rcu: Rename __is_kfree_rcu_offset() macro Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 15/24] rcu: Rename kfree_call_rcu() to the kvfree_call_rcu() Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 16/24] mm/list_lru.c: Rename kvfree_rcu() to local variant Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 17/24] rcu: Introduce 2 arg kvfree_rcu() interface Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 18/24] mm/list_lru.c: Remove kvfree_rcu_local() function Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 19/24] rcu/tree: Support reclaim for head-less object Uladzislau Rezki (Sony)
2020-05-01 22:39 ` Paul E. McKenney
2020-05-04 0:12 ` Joel Fernandes
2020-05-04 0:28 ` Paul E. McKenney
2020-05-04 0:32 ` Joel Fernandes
2020-05-04 14:21 ` Uladzislau Rezki
2020-05-04 15:31 ` Paul E. McKenney
2020-05-04 16:56 ` Uladzislau Rezki
2020-05-04 17:08 ` Paul E. McKenney
2020-05-04 12:57 ` Uladzislau Rezki
2020-04-28 20:58 ` [PATCH 20/24] rcu/tree: Make kvfree_rcu() tolerate any alignment Uladzislau Rezki (Sony)
2020-05-01 23:00 ` Paul E. McKenney
2020-05-04 0:24 ` Joel Fernandes
2020-05-04 0:29 ` Paul E. McKenney
2020-05-04 0:31 ` Joel Fernandes
2020-05-04 12:56 ` Uladzislau Rezki
2020-04-28 20:59 ` [PATCH 21/24] rcu/tiny: move kvfree_call_rcu() out of header Uladzislau Rezki (Sony)
2020-05-01 23:03 ` Paul E. McKenney
2020-05-04 12:45 ` Uladzislau Rezki
2020-05-06 18:29 ` Uladzislau Rezki
2020-05-06 18:45 ` Paul E. McKenney
2020-05-07 17:34 ` Uladzislau Rezki
2020-04-28 20:59 ` [PATCH 22/24] rcu/tiny: support reclaim for head-less object Uladzislau Rezki (Sony)
2020-05-01 23:06 ` Paul E. McKenney
2020-05-04 0:27 ` Joel Fernandes
2020-05-04 12:45 ` Uladzislau Rezki
2020-04-28 20:59 ` [PATCH 23/24] rcu: Introduce 1 arg kvfree_rcu() interface Uladzislau Rezki (Sony)
2020-04-28 20:59 ` [PATCH 24/24] lib/test_vmalloc.c: Add test cases for kvfree_rcu() Uladzislau Rezki (Sony)
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