4.9-stable review patch. If anyone has any objections, please let me know.
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From: Heiko Carstens heiko.carstens@de.ibm.com
[ Upstream commit 68cc795d1933285705ced6d841ef66c00ce98cbe ]
The "topology=off" kernel parameter is supposed to prevent the kernel to use hardware topology information to generate scheduling domains etc. For an unknown reason I implemented this in a very odd way back then: instead of simply clearing the MACHINE_HAS_TOPOLOGY flag within the lowcore I added a second variable which indicated that topology information should not be used. This is more than suboptimal since it partially doesn't work. For the fake NUMA case topology information is still considered and scheduling domains will be created based on this. To fix this and to simplify the code get rid of the extra variable and implement the "topology=off" case like it is done for other features.
Signed-off-by: Heiko Carstens heiko.carstens@de.ibm.com Signed-off-by: Martin Schwidefsky schwidefsky@de.ibm.com Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/s390/kernel/early.c | 12 ++++++++++++ arch/s390/kernel/topology.c | 11 ++--------- 2 files changed, 14 insertions(+), 9 deletions(-)
--- a/arch/s390/kernel/early.c +++ b/arch/s390/kernel/early.c @@ -363,6 +363,18 @@ static inline void save_vector_registers #endif }
+static int __init topology_setup(char *str) +{ + bool enabled; + int rc; + + rc = kstrtobool(str, &enabled); + if (!rc && !enabled) + S390_lowcore.machine_flags &= ~MACHINE_HAS_TOPOLOGY; + return rc; +} +early_param("topology", topology_setup); + static int __init disable_vector_extension(char *str) { S390_lowcore.machine_flags &= ~MACHINE_FLAG_VX; --- a/arch/s390/kernel/topology.c +++ b/arch/s390/kernel/topology.c @@ -37,7 +37,6 @@ static void set_topology_timer(void); static void topology_work_fn(struct work_struct *work); static struct sysinfo_15_1_x *tl_info;
-static bool topology_enabled = true; static DECLARE_WORK(topology_work, topology_work_fn);
/* @@ -56,7 +55,7 @@ static cpumask_t cpu_group_map(struct ma cpumask_t mask;
cpumask_copy(&mask, cpumask_of(cpu)); - if (!topology_enabled || !MACHINE_HAS_TOPOLOGY) + if (!MACHINE_HAS_TOPOLOGY) return mask; for (; info; info = info->next) { if (cpumask_test_cpu(cpu, &info->mask)) @@ -71,7 +70,7 @@ static cpumask_t cpu_thread_map(unsigned int i;
cpumask_copy(&mask, cpumask_of(cpu)); - if (!topology_enabled || !MACHINE_HAS_TOPOLOGY) + if (!MACHINE_HAS_TOPOLOGY) return mask; cpu -= cpu % (smp_cpu_mtid + 1); for (i = 0; i <= smp_cpu_mtid; i++) @@ -413,12 +412,6 @@ static const struct cpumask *cpu_drawer_ return &per_cpu(cpu_topology, cpu).drawer_mask; }
-static int __init early_parse_topology(char *p) -{ - return kstrtobool(p, &topology_enabled); -} -early_param("topology", early_parse_topology); - static struct sched_domain_topology_level s390_topology[] = { { cpu_thread_mask, cpu_smt_flags, SD_INIT_NAME(SMT) }, { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },