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Wysocki" , Danilo Krummrich , Alan Stern Cc: Saravana Kannan , Christoph Hellwig , Eric Dumazet , Johan Hovold , Leon Romanovsky , Alexander Lobakin , Alexey Kardashevskiy , Robin Murphy , Douglas Anderson , Mark Brown , ardb@kernel.org, catalin.marinas@arm.com, chleroy@kernel.org, david@kernel.org, driver-core@lists.linux.dev, kees@kernel.org, kevin.brodsky@arm.com, lenb@kernel.org, linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, maddy@linux.ibm.com, maz@kernel.org, miko.lenczewski@arm.com, mpe@ellerman.id.au, npiggin@gmail.com, osalvador@suse.de, oupton@kernel.org, peterz@infradead.org, tglx@kernel.org, will@kernel.org, yangyicong@hisilicon.com, yeoreum.yun@arm.com Subject: [PATCH v4 9/9] driver core: Replace dev->offline + ->offline_disabled with accessors Date: Fri, 3 Apr 2026 17:05:03 -0700 Message-ID: <20260403170432.v4.9.I897d478b4a9361d79cd5073207c1062fd4d0d0e4@changeid> X-Mailer: git-send-email 2.53.0.1213.gd9a14994de-goog In-Reply-To: <20260404000644.522677-1-dianders@chromium.org> References: <20260404000644.522677-1-dianders@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 098BE4000A X-Stat-Signature: x5sq3cfuactf9p681e7h5w97aasz3so8 X-Rspamd-Server: rspam06 X-HE-Tag: 1775261266-104357 X-HE-Meta: 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 Djfs6Vx+ fZcDFwriGZY4Wy1i8pw7RQTof5nDBVBFH5OjImWb/q+cVlx2rnyYzvS3FeI2VJBMmv/PWnE27Jf9lO6/Vl35HDhOd3T/mhqj8nPYPyfPc31UsG1rumdsg6BCVXRDG2JuRTO5FegOkDqYHfLQTEGM9NMP0agWKJy/30QYQNXu5sZa5b3VKjn9/FaaRT5VquApjX4EM6GV4tayhAKiSlwDMXStwcvCRf0POyzLLFEcNRRdY0KqR40i3FSYinvBq6Aoq5yEbp+sdY8ZTX6BLOIrhKtWdVz4y9MJIlA+JXBg369p6hpCQp//B3PMqVlqrFfahKk9UCcAtlzmAUEmBbz+GVvL1dAjUHYh7H7HzQnUE/Bo3iUNm4le0f5nJ1P61ioDRcg2kulwE1gBvQj23odj7MN+lrkDBHrceCu393jQ0ld8GekiGL4V0uPpmxu0BKd98sTLB+lU382qXRoc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 Acked-by: Mark Brown Signed-off-by: Douglas Anderson --- 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 v4: - Use accessor functions for flags Changes in v3: - New arch/arm64/kernel/cpufeature.c | 2 +- .../powerpc/platforms/pseries/hotplug-memory.c | 4 ++-- drivers/acpi/scan.c | 2 +- drivers/base/core.c | 18 +++++++++--------- drivers/base/cpu.c | 4 ++-- drivers/base/memory.c | 2 +- include/linux/device.h | 12 ++++++------ kernel/cpu.c | 4 ++-- 8 files changed, 24 insertions(+), 24 deletions(-) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 32c2dbcc0c64..c832aa565dc2 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; + dev_set_offline_disabled(get_cpu_device(lucky_winner)); 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..75f85a5da981 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 && dev_offline(&mem_block->dev)) rc = device_online(&mem_block->dev); - else if (!online && !mem_block->dev.offline) + else if (!online && !dev_offline(&mem_block->dev)) rc = device_offline(&mem_block->dev); else rc = 0; diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index e8cdbdb46fdb..1353adbcc234 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -122,7 +122,7 @@ 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) && !dev_offline(pn->dev)) { if (uevent) kobject_uevent_env(&pn->dev->kobj, KOBJ_CHANGE, envp); diff --git a/drivers/base/core.c b/drivers/base/core.c index f12f3b53b4d0..79c85dbcffad 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2788,7 +2788,7 @@ static ssize_t online_show(struct device *dev, struct device_attribute *attr, bool val; device_lock(dev); - val = !dev->offline; + val = !dev_offline(dev); device_unlock(dev); return sysfs_emit(buf, "%u\n", val); } @@ -2913,7 +2913,7 @@ 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) && !dev_offline_disabled(dev)) { error = device_create_file(dev, &dev_attr_online); if (error) goto err_remove_dev_groups; @@ -4178,7 +4178,7 @@ 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) && !dev_offline(dev) ? -EBUSY : 0; } /** @@ -4196,7 +4196,7 @@ int device_offline(struct device *dev) { int ret; - if (dev->offline_disabled) + if (dev_offline_disabled(dev)) return -EPERM; ret = device_for_each_child(dev, NULL, device_check_offline); @@ -4205,13 +4205,13 @@ int device_offline(struct device *dev) device_lock(dev); if (device_supports_offline(dev)) { - if (dev->offline) { + if (dev_offline(dev)) { ret = 1; } else { ret = dev->bus->offline(dev); if (!ret) { kobject_uevent(&dev->kobj, KOBJ_OFFLINE); - dev->offline = true; + dev_set_offline(dev); } } } @@ -4236,11 +4236,11 @@ int device_online(struct device *dev) device_lock(dev); if (device_supports_offline(dev)) { - if (dev->offline) { + if (dev_offline(dev)) { ret = dev->bus->online(dev); if (!ret) { kobject_uevent(&dev->kobj, KOBJ_ONLINE); - dev->offline = false; + dev_clear_offline(dev); } } else { ret = 1; @@ -4714,7 +4714,7 @@ 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) && !dev_offline_disabled(dev)) { /* 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..19d288a3c80c 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); + dev_assign_offline_disabled(&cpu->dev, !cpu->hotpluggable); + dev_assign_offline(&cpu->dev, !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..5005654f44fa 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; + dev_assign_offline(&memory->dev, memory->state == MEM_OFFLINE); ret = device_register(&memory->dev); if (ret) { diff --git a/include/linux/device.h b/include/linux/device.h index 8132aab17e04..65fc6c566cc6 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -485,6 +485,8 @@ 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 = 0, @@ -495,6 +497,8 @@ enum struct_device_flags { DEV_FLAG_STATE_SYNCED = 5, DEV_FLAG_DMA_COHERENT = 6, DEV_FLAG_OF_NODE_REUSED = 7, + DEV_FLAG_OFFLINE_DISABLED = 8, + DEV_FLAG_OFFLINE = 9, DEV_FLAG_COUNT }; @@ -573,9 +577,6 @@ enum struct_device_flags { * @removable: Whether the device can be removed from the system. This * 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 @@ -680,9 +681,6 @@ struct device { enum device_removable removable; - bool offline_disabled:1; - bool offline:1; - DECLARE_BITMAP(flags, DEV_FLAG_COUNT); }; @@ -716,6 +714,8 @@ __create_dev_flag_accessors(dma_ops_bypass, DEV_FLAG_DMA_OPS_BYPASS); __create_dev_flag_accessors(state_synced, DEV_FLAG_STATE_SYNCED); __create_dev_flag_accessors(dma_coherent, DEV_FLAG_DMA_COHERENT); __create_dev_flag_accessors(of_node_reused, DEV_FLAG_OF_NODE_REUSED); +__create_dev_flag_accessors(offline_disabled, DEV_FLAG_OFFLINE_DISABLED); +__create_dev_flag_accessors(offline, DEV_FLAG_OFFLINE); /** * struct device_link - Device link representation. diff --git a/kernel/cpu.c b/kernel/cpu.c index bc4f7a9ba64e..f975bb34915b 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; + dev_set_offline(dev); /* 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; + dev_clear_offline(dev); /* Tell user space about the state change */ kobject_uevent(&dev->kobj, KOBJ_ONLINE); } -- 2.53.0.1213.gd9a14994de-goog