From: Michael Bringmann <mwb@linux.vnet.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Michael Bringmann <mwb@linux.vnet.ibm.com>,
Nathan Fontenot <nfont@linux.vnet.ibm.com>,
John Allen <jallen@linux.vnet.ibm.com>,
Tyrel Datwyler <tyreld@linux.vnet.ibm.com>,
Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Subject: [PATCH v06 4/9] mobility/numa: Ensure numa update does not overlap
Date: Mon, 9 Jul 2018 09:58:43 -0500 [thread overview]
Message-ID: <f1b39e79-b109-6bc6-def8-ded4941cfadb@linux.vnet.ibm.com> (raw)
In-Reply-To: <4e6b3582-0033-b232-3769-226ba6f68eac@linux.vnet.ibm.com>
mobility/numa: Ensure that numa_update_cpu_topology() can not be
entered multiple times concurrently. It may be accessed through
many different paths / concurrent work functions, and the lock
ordering may be difficult to ensure otherwise.
Signed-off-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
---
arch/powerpc/mm/numa.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index a789d57..b22e27a 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1079,6 +1079,7 @@ struct topology_update_data {
static int topology_timer_secs = 1;
static int topology_inited;
static int topology_update_needed;
+static struct mutex topology_update_lock;
/*
* Change polling interval for associativity changes.
@@ -1320,6 +1321,11 @@ int numa_update_cpu_topology(bool cpus_locked)
if (!updates)
return 0;
+ if (!mutex_trylock(&topology_update_lock)) {
+ kfree(updates);
+ return 0;
+ }
+
cpumask_clear(&updated_cpus);
for_each_cpu(cpu, &cpu_associativity_changes_mask) {
@@ -1424,6 +1430,7 @@ int numa_update_cpu_topology(bool cpus_locked)
out:
kfree(updates);
topology_update_needed = 0;
+ mutex_unlock(&topology_update_lock);
return changed;
}
@@ -1598,6 +1605,8 @@ static ssize_t topology_write(struct file *file, const char __user *buf,
static int topology_update_init(void)
{
+ mutex_init(&topology_update_lock);
+
/* Do not poll for changes if disabled at boot */
if (topology_updates_enabled)
start_topology_update();
next prev parent reply other threads:[~2018-07-09 14:58 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-09 14:57 [PATCH v06 0/9] powerpc/hotplug: Update affinity for migrated CPUs Michael Bringmann
2018-07-09 14:58 ` [PATCH v06 1/9] hotplug/cpu: Conditionally acquire/release DRC index Michael Bringmann
2018-07-11 16:00 ` Naveen N. Rao
2018-07-13 15:54 ` Michael Bringmann
2018-07-09 14:58 ` [PATCH v06 2/9] hotplug/cpu: Add operation queuing function Michael Bringmann
2018-07-09 14:58 ` [PATCH v06 3/9] hotplug/cpu: Provide CPU readd operation Michael Bringmann
2018-07-09 14:58 ` Michael Bringmann [this message]
2018-07-09 14:58 ` [PATCH v06 5/9] numa: Disable/enable arch_update_cpu_topology Michael Bringmann
2018-07-09 14:58 ` [PATCH v06 6/9] pmt/numa: Disable arch_update_cpu_topology during CPU readd Michael Bringmann
2018-07-09 14:58 ` [PATCH v06 7/9] powerpc/rtas: Allow disabling rtas_event_scan Michael Bringmann
2018-07-09 14:59 ` [PATCH v06 8/9] hotplug/rtas: No rtas_event_scan during PMT update Michael Bringmann
2018-07-09 14:59 ` [PATCH v06 9/9] hotplug/pmt: Update topology after PMT Michael Bringmann
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