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From:   Leonardo Bras <leonardo@linux.ibm.com>
To:     linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Cc:     Leonardo Bras <leonardo@linux.ibm.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
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        "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
        Christophe Leroy <christophe.leroy@c-s.fr>,
        Andrew Morton <akpm@linux-foundation.org>,
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        Nicholas Piggin <npiggin@gmail.com>,
        Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>,
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        Richard Fontana <rfontana@redhat.com>,
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        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Mike Rapoport <rppt@linux.ibm.com>,
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        Keith Busch <keith.busch@intel.com>
Subject: [PATCH v2 11/11] powerpc/mm/book3s64/pgtable: Uses counting method to skip serializing
Date:   Fri, 20 Sep 2019 16:50:47 -0300
Message-Id: <20190920195047.7703-12-leonardo@linux.ibm.com>
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Skips slow part of serialize_against_pte_lookup if there is no running
lockless pagetable walk.

Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com>
---
 arch/powerpc/mm/book3s64/pgtable.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
index 13239b17a22c..41ca30269fa3 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -95,7 +95,8 @@ static void do_nothing(void *unused)
 void serialize_against_pte_lookup(struct mm_struct *mm)
 {
 	smp_mb();
-	smp_call_function_many(mm_cpumask(mm), do_nothing, NULL, 1);
+	if (running_lockless_pgtbl_walk(mm))
+		smp_call_function_many(mm_cpumask(mm), do_nothing, NULL, 1);
 }
 
 void start_lockless_pgtbl_walk(struct mm_struct *mm)
-- 
2.20.1