From: Heiko Carstens <heiko.carstens@de.ibm.com>
On some smp sysfs store attributes get_online_cpus() may block on
cpu_hotplug.lock, but we hold already smp_cpu_state_mutex. Since the
locking order on cpu hotplug via arch_update_cpu_topology is inverse
this might lead to deadlocks.
So make sure locking order is always the same.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
arch/s390/kernel/smp.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
Index: quilt-2.6/arch/s390/kernel/smp.c
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/smp.c
+++ quilt-2.6/arch/s390/kernel/smp.c
@@ -890,8 +890,8 @@ static ssize_t cpu_configure_store(struc
if (val != 0 && val != 1)
return -EINVAL;
- mutex_lock(&smp_cpu_state_mutex);
get_online_cpus();
+ mutex_lock(&smp_cpu_state_mutex);
rc = -EBUSY;
if (cpu_online(cpu))
goto out;
@@ -919,8 +919,8 @@ static ssize_t cpu_configure_store(struc
break;
}
out:
- put_online_cpus();
mutex_unlock(&smp_cpu_state_mutex);
+ put_online_cpus();
return rc ? rc : count;
}
static SYSDEV_ATTR(configure, 0644, cpu_configure_show, cpu_configure_store);
@@ -1095,8 +1095,8 @@ static ssize_t __ref rescan_store(struct
int cpu;
int rc;
- mutex_lock(&smp_cpu_state_mutex);
get_online_cpus();
+ mutex_lock(&smp_cpu_state_mutex);
newcpus = cpu_present_map;
rc = smp_rescan_cpus();
if (rc)
@@ -1109,8 +1109,8 @@ static ssize_t __ref rescan_store(struct
}
rc = 0;
out:
- put_online_cpus();
mutex_unlock(&smp_cpu_state_mutex);
+ put_online_cpus();
if (!cpus_empty(newcpus))
topology_schedule_update();
return rc ? rc : count;
@@ -1139,16 +1139,16 @@ static ssize_t dispatching_store(struct
if (val != 0 && val != 1)
return -EINVAL;
rc = 0;
- mutex_lock(&smp_cpu_state_mutex);
get_online_cpus();
+ mutex_lock(&smp_cpu_state_mutex);
if (cpu_management == val)
goto out;
rc = topology_set_cpu_management(val);
if (!rc)
cpu_management = val;
out:
- put_online_cpus();
mutex_unlock(&smp_cpu_state_mutex);
+ put_online_cpus();
return rc ? rc : count;
}
static SYSDEV_ATTR(dispatching, 0644, dispatching_show, dispatching_store);
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
--
