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From: Frederic Weisbecker <frederic@kernel.org>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	"David S . Miller" <davem@davemloft.net>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Pavan Kondeti <pkondeti@codeaurora.org>,
	Ingo Molnar <mingo@kernel.org>,
	Joel Fernandes <joel@joelfernandes.org>
Subject: [PATCH 10/37] locking/lockdep: Make mark_lock() fastpath to work with multiple usage at once
Date: Thu, 28 Feb 2019 18:12:15 +0100	[thread overview]
Message-ID: <20190228171242.32144-11-frederic@kernel.org> (raw)
In-Reply-To: <20190228171242.32144-1-frederic@kernel.org>

Now that mark_lock() is going to handle multiple softirq vectors at
once for a given lock usage, the current fast path optimization that
simply check if the new bit usage is already present won't work anymore.

Indeed if the new usage is only partially present, such as for some
softirq vectors and not for others, we may spuriously ignore all the
verifications for the new vectors.

What we must check instead is a bit different: we have to make sure that
the new usage with all its vectors are entirely present in the current
usage mask before ignoring further checks.

Reviewed-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Pavan Kondeti <pkondeti@codeaurora.org>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: David S . Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
---
 kernel/locking/lockdep.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 0988de06a7ed..9a5f2dbc3812 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3159,7 +3159,7 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
 	 * If already set then do not dirty the cacheline,
 	 * nor do any checks:
 	 */
-	if (likely(hlock_class(this)->usage_mask & new_mask))
+	if (likely(!(new_mask & ~hlock_class(this)->usage_mask)))
 		return 1;
 
 	if (!graph_lock())
@@ -3167,7 +3167,7 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
 	/*
 	 * Make sure we didn't race:
 	 */
-	if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
+	if (unlikely(!(new_mask & ~hlock_class(this)->usage_mask))) {
 		graph_unlock();
 		return 1;
 	}
-- 
2.21.0


  parent reply	other threads:[~2019-02-28 17:13 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-28 17:12 [PATCH 00/37] softirq: Per vector masking v3 Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 01/37] locking/lockdep: Move valid_state() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 02/37] locking/lockdep: Use expanded masks on find_usage_*() functions Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 03/37] locking/lockdep: Introduce struct lock_usage Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 04/37] locking/lockdep: Convert usage_mask to u64 Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 05/37] locking/lockdep: Introduce lock usage mask iterator Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 06/37] locking/lockdep: Test all incompatible scenario at once in check_irq_usage() Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 07/37] locking/lockdep: Prepare valid_state() to handle plain masks Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 08/37] locking/lockdep: Prepare check_usage_*() " Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 09/37] locking/lockdep: Prepare state_verbose() to handle all softirqs Frederic Weisbecker
2019-02-28 17:12 ` Frederic Weisbecker [this message]
2019-02-28 17:12 ` [PATCH 11/37] locking/lockdep: Save stack trace for each softirq vector involved Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 12/37] locking/lockdep: Report all usages on mark_lock() verbosity mode Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 13/37] softirq: Macrofy softirq vectors Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 14/37] locking/lockdep: Define per vector softirq lock usage states Frederic Weisbecker
2019-04-09 12:03   ` Peter Zijlstra
2019-02-28 17:12 ` [PATCH 15/37] softirq: Pass softirq vector number to lockdep on vector execution Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 16/37] x86: Revert "x86/irq: Demote irq_cpustat_t::__softirq_pending to u16" Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 17/37] arch/softirq: Rename softirq_pending fields to softirq_data Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 18/37] softirq: Normalize softirq_pending naming scheme Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 19/37] softirq: Convert softirq_pending_*() to set/clear mask scheme Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 20/37] softirq: Introduce disabled softirq vectors bits Frederic Weisbecker
2019-03-01 11:29   ` Sebastian Andrzej Siewior
2019-02-28 17:12 ` [PATCH 21/37] softirq: Rename _local_bh_enable() to local_bh_enable_no_softirq() Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 22/37] softirq: Move vectors bits to bottom_half.h Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 23/37] x86: Init softirq enabled field Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 24/37] parisc: " Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 25/37] powerpc: " Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 26/37] softirq: Init softirq enabled field for default irq_stat definition Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 27/37] softirq: Check enabled vectors before processing Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 28/37] softirq: Remove stale comment Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 29/37] softirq: Uninline !CONFIG_TRACE_IRQFLAGS __local_bh_disable_ip() Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 30/37] softirq: Prepare for mixing all/per-vector masking Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 31/37] softirq: Support per vector masking Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 32/37] locking/lockdep: Remove redundant softirqs on check Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 33/37] locking/lockdep: Update check_flags() according to new layout Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 34/37] locking/lockdep: Branch the new vec-finegrained softirq masking to lockdep Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 35/37] softirq: Allow to soft interrupt vector-specific masked contexts Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 36/37] locking: Introduce spin_[un]lock_bh_mask() Frederic Weisbecker
2019-02-28 17:12 ` [PATCH 37/37] net: Make softirq vector masking finegrained on release_sock() Frederic Weisbecker
2019-02-28 17:33 ` [PATCH 00/37] softirq: Per vector masking v3 Linus Torvalds
2019-03-01  3:45   ` Frederic Weisbecker
2019-03-01 16:51     ` Linus Torvalds
2019-03-08 15:30       ` Frederic Weisbecker

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