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From: Peter Zijlstra <peterz@infradead.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	LKML <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"David S. Miller" <davem@davemloft.net>,
	Tony Luck <tony.luck@intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Chris Zankel <chris@zankel.net>,
	Max Filippov <jcmvbkbc@gmail.com>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Waiman Long <Waiman.Long@hpe.com>
Subject: Re: [PATCH 03/11] locking, rwsem: introduce basis for down_write_killable
Date: Wed, 11 May 2016 10:44:01 +0200	[thread overview]
Message-ID: <20160511084401.GH3193@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160511082853.GF16677@dhcp22.suse.cz>

On Wed, May 11, 2016 at 10:28:53AM +0200, Michal Hocko wrote:

> Does the following look correct/reasonable? This is absolutely untested
> and more for a discussion:

I would much rather see it in common; something like so perhaps.

---
 kernel/locking/rwsem-xadd.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index df4dcb883b50..5d7f2831a475 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -487,11 +487,9 @@ __rwsem_down_write_failed_common(struct rw_semaphore *sem, int state)
 
 		/* Block until there are no active lockers. */
 		do {
-			if (signal_pending_state(state, current)) {
-				raw_spin_lock_irq(&sem->wait_lock);
-				ret = ERR_PTR(-EINTR);
-				goto out;
-			}
+			if (signal_pending_state(state, current))
+				goto out_nolock;
+
 			schedule();
 			set_current_state(state);
 		} while ((count = sem->count) & RWSEM_ACTIVE_MASK);
@@ -504,6 +502,18 @@ __rwsem_down_write_failed_common(struct rw_semaphore *sem, int state)
 	raw_spin_unlock_irq(&sem->wait_lock);
 
 	return ret;
+
+out_nolock:
+	__set_current_state(TASK_RUNNING);
+	raw_spin_lock_irq(&sem->wait_lock);
+	list_del(&waiter.list);
+	if (list_empty(&sem->wait_list))
+		rwsem_atomic_update(-RWSEM_WAITING_BIAS, sem);
+	else
+		__rwsem_do_wake(sem, RWSEM_WAKE_READERS);
+	raw_spin_unlock_irq(&sem->wait_lock);
+
+	return ERR_PTR(-EINTR);
 }
 
 __visible struct rw_semaphore * __sched

  reply	other threads:[~2016-05-11  8:44 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-01 11:04 [PATCH 0/11] introduce down_write_killable for rw_semaphore v2 Michal Hocko
2016-04-01 11:04 ` [PATCH 01/11] locking, rwsem: get rid of __down_write_nested Michal Hocko
2016-04-02  0:28   ` Davidlohr Bueso
2016-04-01 11:04 ` [PATCH 02/11] locking, rwsem: drop explicit memory barriers Michal Hocko
2016-04-02  1:17   ` Davidlohr Bueso
2016-04-04  9:03     ` Michal Hocko
2016-04-04  9:06       ` [PATCH 1/2] xtensa, rwsem: drop superfluous arch specific implementation Michal Hocko
2016-04-04  9:06         ` [PATCH 2/2] sh, " Michal Hocko
2016-04-06  9:26           ` Peter Zijlstra
2016-04-06  9:50             ` Geert Uytterhoeven
2016-04-06 10:27               ` Peter Zijlstra
2016-04-04 10:23         ` [PATCH 1/2] xtensa, " Max Filippov
2016-04-06  9:06     ` [PATCH] sparc, " Michal Hocko
2016-04-01 11:04 ` [PATCH 03/11] locking, rwsem: introduce basis for down_write_killable Michal Hocko
2016-04-02  4:41   ` Davidlohr Bueso
2016-04-04  9:17     ` Michal Hocko
2016-04-04  9:21       ` Peter Zijlstra
2016-04-07  6:58       ` Davidlohr Bueso
2016-04-07  7:38         ` Michal Hocko
2016-05-10 10:43   ` Tetsuo Handa
2016-05-10 11:53     ` Michal Hocko
2016-05-10 12:38       ` Peter Zijlstra
2016-05-10 13:57         ` Tetsuo Handa
2016-05-11  7:23         ` Michal Hocko
2016-05-11  8:28           ` Michal Hocko
2016-05-11  8:44             ` Peter Zijlstra [this message]
2016-05-11  9:04               ` Michal Hocko
2016-05-11  9:17                 ` Peter Zijlstra
2016-05-11  9:31                   ` Michal Hocko
2016-05-11  9:41                     ` Peter Zijlstra
2016-05-11 13:59                       ` Michal Hocko
2016-05-11 18:03                         ` Michal Hocko
2016-05-12 11:57                           ` [PATCH] locking, rwsem: Fix down_write_killable() Peter Zijlstra
2016-05-12 12:15                             ` [tip:locking/rwsem] locking/rwsem: " tip-bot for Peter Zijlstra
2016-05-12 16:59                             ` [PATCH] locking, rwsem: " Michal Hocko
2016-05-15 20:57                             ` [tip:locking/rwsem] locking/rwsem: " tip-bot for Peter Zijlstra
2016-05-12 12:12                           ` [PATCH 03/11] locking, rwsem: introduce basis for down_write_killable Peter Zijlstra
2016-05-12 12:19                             ` Michal Hocko
2016-05-12 13:58                               ` Peter Zijlstra
2016-05-12 19:42                               ` Waiman Long
2016-05-11  8:35           ` Peter Zijlstra
2016-05-11  9:02             ` Michal Hocko
2016-04-01 11:04 ` [PATCH 04/11] alpha, rwsem: provide __down_write_killable Michal Hocko
2016-04-01 11:04 ` [PATCH 05/11] ia64, " Michal Hocko
2016-04-01 11:04 ` [PATCH 06/11] s390, " Michal Hocko
2016-04-01 11:04 ` [PATCH 07/11] sh, " Michal Hocko
2016-04-01 11:04 ` [PATCH 08/11] sparc, " Michal Hocko
2016-04-01 11:04 ` [PATCH 09/11] xtensa, " Michal Hocko
2016-04-01 11:04 ` [PATCH 10/11] x86, " Michal Hocko
2016-04-06 18:31   ` Peter Zijlstra
2016-04-01 11:04 ` [PATCH 11/11] locking, rwsem: provide down_write_killable Michal Hocko
  -- strict thread matches above, loose matches on Subject: below --
2016-02-29 12:58 [PATCH 0/11] introduce down_write_killable for rw_semaphore Michal Hocko
2016-02-29 12:58 ` [PATCH 03/11] locking, rwsem: introduce basis for down_write_killable Michal Hocko
2016-03-30 13:25   ` Peter Zijlstra
2016-03-31  8:33     ` Michal Hocko
2016-03-31  8:44       ` Peter Zijlstra

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