From 1c4e2d70afb132058bfe979f6854c1d0a732b556 Mon Sep 17 00:00:00 2001 From: Igor Mammedov Date: Tue, 14 May 2013 16:46:07 +0200 Subject: cpu: make sure that cpu/online file created before KOBJ_ADD is emitted It fixes race between udev and hotplugged CPU registration by defining "online" attribute statically, so that device_add() would create it before notifying udev about new CPU. Original issue report is at https://lkml.org/lkml/2012/4/30/198 " > On Mon, Apr 30, 2012 at 11:36:23AM -0400, Konrad Rzeszutek Wilk wrote: > > Hey Greg, > > > > Hoping you can help with some guidance on how to fix this. > > > > The issue is with CPU hotplug is that when a CPU goes up > > it calls 'arch_register_cpu' which eventually calls > > register_cpu. That function does these two things: > > > > 251 error = device_register(&cpu->dev); > > 252 if (!error && cpu->hotpluggable) > > 253 register_cpu_control(cpu); > > > > and the device_register creates a nice little SysFS directory: > > > > /sys/devices/system/cpu/cpu2/ which at line 251 has the 'add' attribute > > but no 'online' attribute. udev then tries to echo 1 to the 'online' > > and it we get: > > udevd-work[2421]: error opening ATTR{/sys/devices/system/cpu/cpu2/online} for writing: No such file or directory > > > > Line 253 creates said 'online' and at that time udev [or the system admin] > > can write 1 to 'online' and the CPU goes up. > > > > So .. any thoughts? Is there some way to inhibit from uevent being sent > > until line 253 has run? " Signed-off-by: Igor Mammedov Tested-by: Konrad Rzeszutek Wilk Reviewed-by: Konrad Rzeszutek Wilk Signed-off-by: Greg Kroah-Hartman --- drivers/base/cpu.c | 34 +++++++++++++++++++++------------- 1 file changed, 21 insertions(+), 13 deletions(-) (limited to 'drivers/base/cpu.c') diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index 8f9e264220d2..c377673320ed 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -85,18 +85,21 @@ static ssize_t __ref store_online(struct device *dev, } static DEVICE_ATTR(online, 0644, show_online, store_online); -static void __cpuinit register_cpu_control(struct cpu *cpu) -{ - device_create_file(&cpu->dev, &dev_attr_online); -} +static struct attribute *hotplug_cpu_attrs[] = { + &dev_attr_online.attr, + NULL +}; + +static struct attribute_group hotplug_cpu_attr_group = { + .attrs = hotplug_cpu_attrs, +}; + void unregister_cpu(struct cpu *cpu) { int logical_cpu = cpu->dev.id; unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); - device_remove_file(&cpu->dev, &dev_attr_online); - device_unregister(&cpu->dev); per_cpu(cpu_sys_devices, logical_cpu) = NULL; return; @@ -122,11 +125,6 @@ static ssize_t cpu_release_store(struct device *dev, static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store); static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store); #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */ - -#else /* ... !CONFIG_HOTPLUG_CPU */ -static inline void register_cpu_control(struct cpu *cpu) -{ -} #endif /* CONFIG_HOTPLUG_CPU */ #ifdef CONFIG_KEXEC @@ -183,6 +181,16 @@ static const struct attribute_group *common_cpu_attr_groups[] = { NULL }; +static const struct attribute_group *hotplugable_cpu_attr_groups[] = { +#ifdef CONFIG_KEXEC + &crash_note_cpu_attr_group, +#endif +#ifdef CONFIG_HOTPLUG_CPU + &hotplug_cpu_attr_group, +#endif + NULL +}; + /* * Print cpu online, possible, present, and system maps */ @@ -298,9 +306,9 @@ int __cpuinit register_cpu(struct cpu *cpu, int num) cpu->dev.bus->uevent = arch_cpu_uevent; #endif cpu->dev.groups = common_cpu_attr_groups; + if (cpu->hotpluggable) + cpu->dev.groups = hotplugable_cpu_attr_groups; error = device_register(&cpu->dev); - if (!error && cpu->hotpluggable) - register_cpu_control(cpu); if (!error) per_cpu(cpu_sys_devices, num) = &cpu->dev; if (!error) -- cgit v1.2.3-59-g8ed1b