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From:   Leonardo Bras <leonardo@linux.ibm.com>
To:     linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
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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>,
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        Dan Williams <dan.j.williams@intel.com>,
        Nicholas Piggin <npiggin@gmail.com>,
        Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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        Allison Randal <allison@lohutok.net>,
        Mike Rapoport <rppt@linux.ibm.com>,
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        Jason Gunthorpe <jgg@ziepe.ca>,
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        Keith Busch <keith.busch@intel.com>
Subject: [PATCH v3 11/11] powerpc/mm/book3s64/pgtable: Uses counting method to skip serializing
Date:   Tue, 24 Sep 2019 18:24:28 -0300
Message-Id: <20190924212427.7734-12-leonardo@linux.ibm.com>
In-Reply-To: <20190924212427.7734-1-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 0b86884a8097..e2aa6572f03f 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);
 }
 
 /*
-- 
2.20.1