linux-kernel - [PATCH V2] arch_topology: Clear LLC sibling when cacheinfo teardown

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Date:   Tue, 14 Mar 2023 15:53:45 +0800
From:   Song Shuai <suagrfillet@...il.com>
To:     sudeep.holla@....com, gregkh@...uxfoundation.org,
        rafael@...nel.org, conor.dooley@...rochip.com,
        ionela.voinescu@....com
Cc:     linux-kernel@...r.kernel.org, Song Shuai <suagrfillet@...il.com>
Subject: [PATCH V2] arch_topology: Clear LLC sibling when cacheinfo teardown

The teardown of CPUHP_AP_BASE_CACHEINFO_ONLINE now only invokes
free_cache_attributes() to clear share_cpu_map of cacheinfo list.
At the same time, clearing cpu_topology[].llc_sibling is
called quite late at the teardown code in hotplug STARTING section.

To avoid the incorrect LLC sibling masks generated, move its clearing
right after free_cache_attributes().

Link: https://lore.kernel.org/linux-kernel/20230313102752.1134472-1-suagrfillet@gmail.com/
Fixes: 3fcbf1c77d08 ("arch_topology: Fix cache attributes detection in the CPU hotplug path")
Signed-off-by: Song Shuai <suagrfillet@...il.com>
---
changes from V1:
 - fix implicit declaration of clear_llc_topology
---
 drivers/base/arch_topology.c  | 16 ++++++++++++++--
 drivers/base/cacheinfo.c      |  2 ++
 include/linux/arch_topology.h |  3 +++
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index b1c1dd38ab01..8681654d6c07 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -769,6 +769,20 @@ void update_siblings_masks(unsigned int cpuid)
 	}
 }
 
+void clear_llc_topology(unsigned int cpu)
+{
+	int sib;
+
+	for_each_cpu(sib, topology_llc_cpumask(cpu)) {
+		if (sib == cpu)
+			continue;
+		if (last_level_cache_is_shared(cpu, sib)) {
+			cpumask_clear_cpu(cpu, topology_llc_cpumask(sib));
+			cpumask_clear_cpu(sib, topology_llc_cpumask(cpu));
+		}
+	}
+}
+
 static void clear_cpu_topology(int cpu)
 {
 	struct cpu_topology *cpu_topo = &cpu_topology[cpu];
@@ -811,8 +825,6 @@ void remove_cpu_topology(unsigned int cpu)
 		cpumask_clear_cpu(cpu, topology_sibling_cpumask(sibling));
 	for_each_cpu(sibling, topology_cluster_cpumask(cpu))
 		cpumask_clear_cpu(cpu, topology_cluster_cpumask(sibling));
-	for_each_cpu(sibling, topology_llc_cpumask(cpu))
-		cpumask_clear_cpu(cpu, topology_llc_cpumask(sibling));
 
 	clear_cpu_topology(cpu);
 }
diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index f6573c335f4c..1c276b30fd5a 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -19,6 +19,7 @@
 #include <linux/slab.h>
 #include <linux/smp.h>
 #include <linux/sysfs.h>
+#include <linux/arch_topology.h>
 
 /* pointer to per cpu cacheinfo */
 static DEFINE_PER_CPU(struct cpu_cacheinfo, ci_cpu_cacheinfo);
@@ -814,6 +815,7 @@ static int cacheinfo_cpu_pre_down(unsigned int cpu)
 		cpu_cache_sysfs_exit(cpu);
 
 	free_cache_attributes(cpu);
+	clear_llc_topology(cpu);
 	return 0;
 }
 
diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h
index a07b510e7dc5..569e05607934 100644
--- a/include/linux/arch_topology.h
+++ b/include/linux/arch_topology.h
@@ -89,9 +89,12 @@ void store_cpu_topology(unsigned int cpuid);
 const struct cpumask *cpu_coregroup_mask(int cpu);
 const struct cpumask *cpu_clustergroup_mask(int cpu);
 void update_siblings_masks(unsigned int cpu);
+void clear_llc_topology(unsigned int cpu);
 void remove_cpu_topology(unsigned int cpuid);
 void reset_cpu_topology(void);
 int parse_acpi_topology(void);
+#else
+static inline void clear_llc_topology(unsigned int cpu) { }
 #endif
 
 #endif /* _LINUX_ARCH_TOPOLOGY_H_ */
-- 
2.20.1