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From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com,
	rostedt@goodmis.org, frederic@kernel.org,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Subject: [PATCH rcu 1/3] srcu: Remove smp_mb() from srcu_read_unlock_lite()
Date: Mon, 11 Nov 2024 17:31:41 -0800	[thread overview]
Message-ID: <20241112013143.1926484-1-paulmck@kernel.org> (raw)
In-Reply-To: <bb96e032-4f7d-41bf-a675-81350dca8d0a@paulmck-laptop>

The srcu_read_unlock_lite() function invokes __srcu_read_unlock() instead
of __srcu_read_unlock_lite(), which means that it is doing an unnecessary
smp_mb().  This is harmless other than the performance degradation.

This commit therefore switches to __srcu_read_unlock_lite().

Reported-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Closes: https://lore.kernel.org/all/d07e8f4a-d5ff-4c8e-8e61-50db285c57e9@amd.com/
Fixes: c0f08d6b5a61 ("srcu: Add srcu_read_lock_lite() and srcu_read_unlock_lite()")
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
---
 include/linux/srcu.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 512a8c54ba5ba..fff6265818d4f 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -373,7 +373,7 @@ static inline void srcu_read_unlock_lite(struct srcu_struct *ssp, int idx)
 	WARN_ON_ONCE(idx & ~0x1);
 	srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_LITE);
 	srcu_lock_release(&ssp->dep_map);
-	__srcu_read_unlock(ssp, idx);
+	__srcu_read_unlock_lite(ssp, idx);
 }
 
 /**
-- 
2.40.1


  reply	other threads:[~2024-11-12  1:31 UTC|newest]

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-09 18:07 [PATCH rcu 0/12] SRCU-lite changes for v6.13 Paul E. McKenney
2024-10-09 18:07 ` [PATCH rcu 01/12] srcu: Rename srcu_might_be_idle() to srcu_should_expedite() Paul E. McKenney
2024-10-14  8:56   ` Neeraj Upadhyay
2024-10-09 18:07 ` [PATCH rcu 02/12] srcu: Introduce srcu_gp_is_expedited() helper function Paul E. McKenney
2024-10-14  8:57   ` Neeraj Upadhyay
2024-10-09 18:07 ` [PATCH rcu 03/12] srcu: Renaming in preparation for additional reader flavor Paul E. McKenney
2024-10-14  9:10   ` Neeraj Upadhyay
2024-10-14 16:52     ` Paul E. McKenney
2024-10-15  3:25       ` Neeraj Upadhyay
2024-10-09 18:07 ` [PATCH rcu 04/12] srcu: Bit manipulation changes " Paul E. McKenney
2024-10-14  9:12   ` Neeraj Upadhyay
2024-10-14 16:51     ` Paul E. McKenney
2024-10-15  3:32       ` Neeraj Upadhyay
2024-10-09 18:07 ` [PATCH rcu 05/12] srcu: Standardize srcu_data pointers to "sdp" and similar Paul E. McKenney
2024-10-14  9:15   ` Neeraj Upadhyay
2024-10-14 16:49     ` Paul E. McKenney
2024-10-15  0:29       ` Paul E. McKenney
2024-10-15  5:10         ` Neeraj Upadhyay
2024-10-09 18:07 ` [PATCH rcu 06/12] srcu: Add srcu_read_lock_lite() and srcu_read_unlock_lite() Paul E. McKenney
2024-11-11 12:54   ` Neeraj Upadhyay
2024-11-11 15:26     ` Paul E. McKenney
2024-11-11 16:51       ` Neeraj Upadhyay
2024-11-12  1:28         ` Paul E. McKenney
2024-11-12  1:31           ` Paul E. McKenney [this message]
2024-11-12  3:17             ` [PATCH rcu 1/3] srcu: Remove smp_mb() from srcu_read_unlock_lite() Neeraj Upadhyay
2024-11-12  1:31           ` [PATCH rcu 2/3] srcu: Check for srcu_read_lock_lite() across all CPUs Paul E. McKenney
2024-11-12  3:28             ` Neeraj Upadhyay
2024-11-12  5:48               ` Paul E. McKenney
2024-11-12  1:31           ` [PATCH rcu 3/3] srcu: Unconditionally record srcu_read_lock_lite() in ->srcu_reader_flavor Paul E. McKenney
2024-11-12  4:32             ` Neeraj Upadhyay
2024-11-12  3:15           ` [PATCH rcu 06/12] srcu: Add srcu_read_lock_lite() and srcu_read_unlock_lite() Neeraj Upadhyay
2024-10-09 18:07 ` [PATCH rcu 07/12] srcu: Allow inlining of __srcu_read_{,un}lock_lite() Paul E. McKenney
2024-10-09 18:07 ` [PATCH rcu 08/12] rcutorture: Expand RCUTORTURE_RDR_MASK_[12] to eight bits Paul E. McKenney
2024-10-09 18:07 ` [PATCH rcu 09/12] rcutorture: Add reader_flavor parameter for SRCU readers Paul E. McKenney
2024-10-09 18:07 ` [PATCH rcu 10/12] rcutorture: Add srcu_read_lock_lite() support to rcutorture.reader_flavor Paul E. McKenney
2024-10-09 18:07 ` [PATCH rcu 11/12] rcutorture: Add light-weight SRCU scenario Paul E. McKenney
2024-10-09 18:07 ` [PATCH rcu 12/12] refscale: Add srcu_read_lock_lite() support using "srcu-lite" Paul E. McKenney
2024-10-10 15:38   ` Frederic Weisbecker
2024-10-10 16:06     ` Paul E. McKenney
2024-10-11 17:39 ` [PATCH v2 rcu 0/13] SRCU-lite changes for v6.13 Paul E. McKenney
2024-10-11 17:39   ` [PATCH v2 rcu 01/13] srcu: Rename srcu_might_be_idle() to srcu_should_expedite() Paul E. McKenney
2024-10-11 17:39   ` [PATCH v2 rcu 02/13] srcu: Introduce srcu_gp_is_expedited() helper function Paul E. McKenney
2024-10-11 17:39   ` [PATCH v2 rcu 03/13] srcu: Renaming in preparation for additional reader flavor Paul E. McKenney
2024-10-11 17:39   ` [PATCH v2 rcu 04/13] srcu: Bit manipulation changes " Paul E. McKenney
2024-10-11 17:39   ` [PATCH v2 rcu 05/13] srcu: Standardize srcu_data pointers to "sdp" and similar Paul E. McKenney
2024-10-11 17:39   ` [PATCH v2 rcu 06/13] srcu: Add srcu_read_lock_lite() and srcu_read_unlock_lite() Paul E. McKenney
2024-10-11 17:39   ` [PATCH v2 rcu 07/13] srcu: Allow inlining of __srcu_read_{,un}lock_lite() Paul E. McKenney
2024-10-11 17:39   ` [PATCH v2 rcu 08/13] rcutorture: Expand RCUTORTURE_RDR_MASK_[12] to eight bits Paul E. McKenney
2024-10-11 17:39   ` [PATCH v2 rcu 09/13] rcutorture: Add reader_flavor parameter for SRCU readers Paul E. McKenney
2024-10-11 17:39   ` [PATCH v2 rcu 10/13] rcutorture: Add srcu_read_lock_lite() support to rcutorture.reader_flavor Paul E. McKenney
2024-10-11 17:39   ` [PATCH v2 rcu 11/13] rcutorture: Add light-weight SRCU scenario Paul E. McKenney
2024-10-11 17:39   ` [PATCH v2 rcu 12/13] refscale: Add srcu_read_lock_lite() support using "srcu-lite" Paul E. McKenney
2024-10-11 17:39   ` [PATCH v2 rcu 13/13] srcu: Improve srcu_read_lock_lite() kernel-doc comment Paul E. McKenney
2024-10-11 17:57     ` Andrii Nakryiko
2024-10-15 15:59       ` Paul E. McKenney
2024-10-15 16:11   ` [PATCH v3 rcu 0/13] SRCU-lite changes for v6.13 Paul E. McKenney
2024-10-15 16:10     ` [PATCH rcu 01/15] srcu: Rename srcu_might_be_idle() to srcu_should_expedite() Paul E. McKenney
2024-10-15 16:10     ` [PATCH rcu 02/15] srcu: Introduce srcu_gp_is_expedited() helper function Paul E. McKenney
2024-10-15 16:11     ` [PATCH rcu 03/15] srcu: Renaming in preparation for additional reader flavor Paul E. McKenney
2024-10-15 16:11     ` [PATCH rcu 04/15] srcu: Bit manipulation changes " Paul E. McKenney
2024-10-15 16:11     ` [PATCH rcu 05/15] srcu: Standardize srcu_data pointers to "sdp" and similar Paul E. McKenney
2024-10-15 16:11     ` [PATCH rcu 06/15] srcu: Improve srcu_read_lock{,_nmisafe}() comments Paul E. McKenney
2024-10-15 16:11     ` [PATCH rcu 07/15] srcu: Create CPP macros for normal and NMI-safe SRCU readers Paul E. McKenney
2024-10-15 16:11     ` [PATCH rcu 08/15] srcu: Add srcu_read_lock_lite() and srcu_read_unlock_lite() Paul E. McKenney
2024-11-04 23:27       ` Frederic Weisbecker
2024-11-05  0:39         ` Paul E. McKenney
2024-11-11 11:17       ` Neeraj Upadhyay
2024-11-11 15:17         ` Paul E. McKenney
2024-11-11 17:46           ` Andrii Nakryiko
2024-11-11 17:51             ` Paul E. McKenney
2024-10-15 16:11     ` [PATCH rcu 09/15] srcu: Allow inlining of __srcu_read_{,un}lock_lite() Paul E. McKenney
2024-10-15 16:11     ` [PATCH rcu 10/15] rcutorture: Expand RCUTORTURE_RDR_MASK_[12] to eight bits Paul E. McKenney
2024-10-15 16:11     ` [PATCH rcu 11/15] rcutorture: Add reader_flavor parameter for SRCU readers Paul E. McKenney
2024-11-12  4:42       ` Neeraj Upadhyay
2024-11-12 19:27         ` Paul E. McKenney
2024-11-13  3:20           ` Neeraj Upadhyay
2024-10-15 16:11     ` [PATCH rcu 12/15] rcutorture: Add srcu_read_lock_lite() support to rcutorture.reader_flavor Paul E. McKenney
2024-10-15 16:11     ` [PATCH rcu 13/15] rcutorture: Add light-weight SRCU scenario Paul E. McKenney
2024-10-15 16:11     ` [PATCH rcu 14/15] refscale: Add srcu_read_lock_lite() support using "srcu-lite" Paul E. McKenney
2024-10-29  0:25       ` [PATCH rcu v4 " Paul E. McKenney
2024-10-15 16:11     ` [PATCH rcu 15/15] srcu: Improve srcu_read_lock_lite() kernel-doc comment Paul E. McKenney
2024-11-12  4:37     ` [PATCH v3 rcu 0/13] SRCU-lite changes for v6.13 Neeraj Upadhyay

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