From 6dedcca610c6d6189b4a54d32118d1654adb73d2 Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Wed, 25 Sep 2013 15:08:27 -0600 Subject: [PATCH] hotplug, powerpc, x86: Remove cpu_hotplug_driver_lock() cpu_hotplug_driver_lock() serializes CPU online/offline operations when ARCH_CPU_PROBE_RELEASE is set. This lock interface is no longer necessary with the following reason: - lock_device_hotplug() now protects CPU online/offline operations, including the probe & release interfaces enabled by ARCH_CPU_PROBE_RELEASE. The use of cpu_hotplug_driver_lock() is redundant. - cpu_hotplug_driver_lock() is only valid when ARCH_CPU_PROBE_RELEASE is defined, which is misleading and is only enabled on powerpc. This patch removes the cpu_hotplug_driver_lock() interface. As a result, ARCH_CPU_PROBE_RELEASE only enables / disables the cpu probe & release interface as intended. There is no functional change in this patch. Signed-off-by: Toshi Kani Reviewed-by: Nathan Fontenot Signed-off-by: Rafael J. Wysocki --- arch/powerpc/kernel/smp.c | 12 ------- arch/powerpc/platforms/pseries/dlpar.c | 43 ++++++++++---------------- arch/x86/kernel/topology.c | 2 -- drivers/base/cpu.c | 15 ++------- include/linux/cpu.h | 13 -------- 5 files changed, 19 insertions(+), 66 deletions(-) diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 8e59abc237d7..930cd8af3503 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -844,18 +844,6 @@ void __cpu_die(unsigned int cpu) smp_ops->cpu_die(cpu); } -static DEFINE_MUTEX(powerpc_cpu_hotplug_driver_mutex); - -void cpu_hotplug_driver_lock() -{ - mutex_lock(&powerpc_cpu_hotplug_driver_mutex); -} - -void cpu_hotplug_driver_unlock() -{ - mutex_unlock(&powerpc_cpu_hotplug_driver_mutex); -} - void cpu_die(void) { if (ppc_md.cpu_die) diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c index 7cfdaae1721a..a8fe5aa3d34f 100644 --- a/arch/powerpc/platforms/pseries/dlpar.c +++ b/arch/powerpc/platforms/pseries/dlpar.c @@ -404,46 +404,38 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count) unsigned long drc_index; int rc; - cpu_hotplug_driver_lock(); rc = strict_strtoul(buf, 0, &drc_index); - if (rc) { - rc = -EINVAL; - goto out; - } + if (rc) + return -EINVAL; parent = of_find_node_by_path("/cpus"); - if (!parent) { - rc = -ENODEV; - goto out; - } + if (!parent) + return -ENODEV; dn = dlpar_configure_connector(drc_index, parent); - if (!dn) { - rc = -EINVAL; - goto out; - } + if (!dn) + return -EINVAL; of_node_put(parent); rc = dlpar_acquire_drc(drc_index); if (rc) { dlpar_free_cc_nodes(dn); - rc = -EINVAL; - goto out; + return -EINVAL; } rc = dlpar_attach_node(dn); if (rc) { dlpar_release_drc(drc_index); dlpar_free_cc_nodes(dn); - goto out; + return rc; } rc = dlpar_online_cpu(dn); -out: - cpu_hotplug_driver_unlock(); + if (rc) + return rc; - return rc ? rc : count; + return count; } static int dlpar_offline_cpu(struct device_node *dn) @@ -516,30 +508,27 @@ static ssize_t dlpar_cpu_release(const char *buf, size_t count) return -EINVAL; } - cpu_hotplug_driver_lock(); rc = dlpar_offline_cpu(dn); if (rc) { of_node_put(dn); - rc = -EINVAL; - goto out; + return -EINVAL; } rc = dlpar_release_drc(*drc_index); if (rc) { of_node_put(dn); - goto out; + return rc; } rc = dlpar_detach_node(dn); if (rc) { dlpar_acquire_drc(*drc_index); - goto out; + return rc; } of_node_put(dn); -out: - cpu_hotplug_driver_unlock(); - return rc ? rc : count; + + return count; } static int __init pseries_dlpar_init(void) diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c index a3f35ebb3b52..649b010da00b 100644 --- a/arch/x86/kernel/topology.c +++ b/arch/x86/kernel/topology.c @@ -66,7 +66,6 @@ int __ref _debug_hotplug_cpu(int cpu, int action) return -EINVAL; lock_device_hotplug(); - cpu_hotplug_driver_lock(); switch (action) { case 0: @@ -91,7 +90,6 @@ int __ref _debug_hotplug_cpu(int cpu, int action) ret = -EINVAL; } - cpu_hotplug_driver_unlock(); unlock_device_hotplug(); return ret; diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index 51f5d7fe2f0b..f48370dfc908 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -44,13 +44,11 @@ static int __ref cpu_subsys_online(struct device *dev) struct cpu *cpu = container_of(dev, struct cpu, dev); int cpuid = dev->id; int from_nid, to_nid; - int ret = -ENODEV; - - cpu_hotplug_driver_lock(); + int ret; from_nid = cpu_to_node(cpuid); if (from_nid == NUMA_NO_NODE) - goto out; + return -ENODEV; ret = cpu_up(cpuid); /* @@ -61,19 +59,12 @@ static int __ref cpu_subsys_online(struct device *dev) if (from_nid != to_nid) change_cpu_under_node(cpu, from_nid, to_nid); - out: - cpu_hotplug_driver_unlock(); return ret; } static int cpu_subsys_offline(struct device *dev) { - int ret; - - cpu_hotplug_driver_lock(); - ret = cpu_down(dev->id); - cpu_hotplug_driver_unlock(); - return ret; + return cpu_down(dev->id); } void unregister_cpu(struct cpu *cpu) diff --git a/include/linux/cpu.h b/include/linux/cpu.h index 801ff9e73679..3434ef7de017 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -185,19 +185,6 @@ extern void cpu_hotplug_enable(void); void clear_tasks_mm_cpumask(int cpu); int cpu_down(unsigned int cpu); -#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE -extern void cpu_hotplug_driver_lock(void); -extern void cpu_hotplug_driver_unlock(void); -#else -static inline void cpu_hotplug_driver_lock(void) -{ -} - -static inline void cpu_hotplug_driver_unlock(void) -{ -} -#endif - #else /* CONFIG_HOTPLUG_CPU */ static inline void cpu_hotplug_begin(void) {} -- 2.20.1