From: Heiko Carstens <heiko.carstens@xxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> --- 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. -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
