In C, bitfields are not necessarily safe to modify from multiple threads without locking. Switch "offline" and "offline_disabled" over to the "flags" field so modifications are safe.
Cc: Rafael J. Wysocki <[email protected]> Cc: Toshi Kani <[email protected]> Signed-off-by: Douglas Anderson <[email protected]> --- Not fixing any known bugs; problem is theoretical and found by code inspection. Change is done somewhat manually and only lightly tested (mostly compile-time tested). Changes in v3: - New arch/arm64/kernel/cpufeature.c | 2 +- .../platforms/pseries/hotplug-memory.c | 4 ++-- drivers/acpi/scan.c | 3 ++- drivers/base/core.c | 19 ++++++++++--------- drivers/base/cpu.c | 4 ++-- drivers/base/memory.c | 2 +- include/linux/device.h | 9 ++++----- kernel/cpu.c | 4 ++-- 8 files changed, 24 insertions(+), 23 deletions(-) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 32c2dbcc0c64..f6f7c35b7a93 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -4042,7 +4042,7 @@ static int enable_mismatched_32bit_el0(unsigned int cpu) */ lucky_winner = cpu_32bit ? cpu : cpumask_any_and(cpu_32bit_el0_mask, cpu_active_mask); - get_cpu_device(lucky_winner)->offline_disabled = true; + set_bit(DEV_FLAG_OFFLINE_DISABLED, &get_cpu_device(lucky_winner)->flags); setup_elf_hwcaps(compat_elf_hwcaps); elf_hwcap_fixup(); pr_info("Asymmetric 32-bit EL0 support detected on CPU %u; CPU hot-unplug disabled on CPU %u\n", diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c index b2f14db59034..d9a0a75ada46 100644 --- a/arch/powerpc/platforms/pseries/hotplug-memory.c +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c @@ -213,9 +213,9 @@ static int dlpar_change_lmb_state(struct drmem_lmb *lmb, bool online) return -EINVAL; } - if (online && mem_block->dev.offline) + if (online && test_bit(DEV_FLAG_OFFLINE, &mem_block->dev.flags)) rc = device_online(&mem_block->dev); - else if (!online && !mem_block->dev.offline) + else if (!online && !test_bit(DEV_FLAG_OFFLINE, &mem_block->dev.flags)) rc = device_offline(&mem_block->dev); else rc = 0; diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index e8cdbdb46fdb..f2707b704468 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -122,7 +122,8 @@ bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent) mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING); list_for_each_entry(pn, &adev->physical_node_list, node) - if (device_supports_offline(pn->dev) && !pn->dev->offline) { + if (device_supports_offline(pn->dev) && + !test_bit(DEV_FLAG_OFFLINE, &pn->dev->flags)) { if (uevent) kobject_uevent_env(&pn->dev->kobj, KOBJ_CHANGE, envp); diff --git a/drivers/base/core.c b/drivers/base/core.c index a87bd40499b6..63d724ece384 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2789,7 +2789,7 @@ static ssize_t online_show(struct device *dev, struct device_attribute *attr, bool val; device_lock(dev); - val = !dev->offline; + val = !test_bit(DEV_FLAG_OFFLINE, &dev->flags); device_unlock(dev); return sysfs_emit(buf, "%u\n", val); } @@ -2914,7 +2914,7 @@ static int device_add_attrs(struct device *dev) if (error) goto err_remove_type_groups; - if (device_supports_offline(dev) && !dev->offline_disabled) { + if (device_supports_offline(dev) && !test_bit(DEV_FLAG_OFFLINE_DISABLED, &dev->flags)) { error = device_create_file(dev, &dev_attr_online); if (error) goto err_remove_dev_groups; @@ -4179,7 +4179,8 @@ static int device_check_offline(struct device *dev, void *not_used) if (ret) return ret; - return device_supports_offline(dev) && !dev->offline ? -EBUSY : 0; + return device_supports_offline(dev) && + !test_bit(DEV_FLAG_OFFLINE, &dev->flags) ? -EBUSY : 0; } /** @@ -4197,7 +4198,7 @@ int device_offline(struct device *dev) { int ret; - if (dev->offline_disabled) + if (test_bit(DEV_FLAG_OFFLINE_DISABLED, &dev->flags)) return -EPERM; ret = device_for_each_child(dev, NULL, device_check_offline); @@ -4206,13 +4207,13 @@ int device_offline(struct device *dev) device_lock(dev); if (device_supports_offline(dev)) { - if (dev->offline) { + if (test_bit(DEV_FLAG_OFFLINE, &dev->flags)) { ret = 1; } else { ret = dev->bus->offline(dev); if (!ret) { kobject_uevent(&dev->kobj, KOBJ_OFFLINE); - dev->offline = true; + set_bit(DEV_FLAG_OFFLINE, &dev->flags); } } } @@ -4237,11 +4238,11 @@ int device_online(struct device *dev) device_lock(dev); if (device_supports_offline(dev)) { - if (dev->offline) { + if (test_bit(DEV_FLAG_OFFLINE, &dev->flags)) { ret = dev->bus->online(dev); if (!ret) { kobject_uevent(&dev->kobj, KOBJ_ONLINE); - dev->offline = false; + clear_bit(DEV_FLAG_OFFLINE, &dev->flags); } } else { ret = 1; @@ -4715,7 +4716,7 @@ static int device_attrs_change_owner(struct device *dev, kuid_t kuid, if (error) return error; - if (device_supports_offline(dev) && !dev->offline_disabled) { + if (device_supports_offline(dev) && !test_bit(DEV_FLAG_OFFLINE_DISABLED, &dev->flags)) { /* Change online device attributes of @dev to @kuid/@kgid. */ error = sysfs_file_change_owner(kobj, dev_attr_online.attr.name, kuid, kgid); diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index 875abdc9942e..e4e6a399def4 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -422,8 +422,8 @@ int register_cpu(struct cpu *cpu, int num) cpu->dev.id = num; cpu->dev.bus = &cpu_subsys; cpu->dev.release = cpu_device_release; - cpu->dev.offline_disabled = !cpu->hotpluggable; - cpu->dev.offline = !cpu_online(num); + assign_bit(DEV_FLAG_OFFLINE_DISABLED, &cpu->dev.flags, !cpu->hotpluggable); + assign_bit(DEV_FLAG_OFFLINE, &cpu->dev.flags, !cpu_online(num)); cpu->dev.of_node = of_get_cpu_node(num, NULL); cpu->dev.groups = common_cpu_attr_groups; if (cpu->hotpluggable) diff --git a/drivers/base/memory.c b/drivers/base/memory.c index a3091924918b..7f42727dde81 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -697,7 +697,7 @@ static int __add_memory_block(struct memory_block *memory) memory->dev.id = memory->start_section_nr / sections_per_block; memory->dev.release = memory_block_release; memory->dev.groups = memory_memblk_attr_groups; - memory->dev.offline = memory->state == MEM_OFFLINE; + assign_bit(DEV_FLAG_OFFLINE, &memory->dev.flags, memory->state == MEM_OFFLINE); ret = device_register(&memory->dev); if (ret) { diff --git a/include/linux/device.h b/include/linux/device.h index f6ca067bacca..fd53aa04cad9 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -484,6 +484,8 @@ struct device_physical_location { * architecture supports non-coherent devices. * @DEV_FLAG_OF_NODE_REUSED: Set if the device-tree node is shared with an * ancestor device. + * @DEV_FLAG_OFFLINE_DISABLED: If set, the device is permanently online. + * @DEV_FLAG_OFFLINE: Set after successful invocation of bus type's .offline(). */ enum struct_device_flags { DEV_FLAG_READY_TO_PROBE, @@ -494,6 +496,8 @@ enum struct_device_flags { DEV_FLAG_STATE_SYNCED, DEV_FLAG_DMA_COHERENT, DEV_FLAG_OF_NODE_REUSED, + DEV_FLAG_OFFLINE_DISABLED, + DEV_FLAG_OFFLINE, }; /** @@ -571,8 +575,6 @@ enum struct_device_flags { * should be set by the subsystem / bus driver that discovered * the device. * - * @offline_disabled: If set, the device is permanently online. - * @offline: Set after successful invocation of bus type's .offline(). * @flags: DEV_FLAG_XXX flags. Use atomic bitfield operations to modify. * * At the lowest level, every device in a Linux system is represented by an @@ -677,9 +679,6 @@ struct device { enum device_removable removable; - bool offline_disabled:1; - bool offline:1; - unsigned long flags; }; diff --git a/kernel/cpu.c b/kernel/cpu.c index bc4f7a9ba64e..15a873ad8025 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -2639,7 +2639,7 @@ static void cpuhp_offline_cpu_device(unsigned int cpu) { struct device *dev = get_cpu_device(cpu); - dev->offline = true; + set_bit(DEV_FLAG_OFFLINE, &dev->flags); /* Tell user space about the state change */ kobject_uevent(&dev->kobj, KOBJ_OFFLINE); } @@ -2648,7 +2648,7 @@ static void cpuhp_online_cpu_device(unsigned int cpu) { struct device *dev = get_cpu_device(cpu); - dev->offline = false; + clear_bit(DEV_FLAG_OFFLINE, &dev->flags); /* Tell user space about the state change */ kobject_uevent(&dev->kobj, KOBJ_ONLINE); } -- 2.53.0.1213.gd9a14994de-goog
