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cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()

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Replace all lock_cpu_hotplug/unlock_cpu_hotplug from the kernel and use
get_online_cpus and put_online_cpus instead as it highlights the
refcount semantics in these operations.

The new API guarantees protection against the cpu-hotplug operation, but
it doesn't guarantee serialized access to any of the local data
structures. Hence the changes needs to be reviewed.

In case of pseries_add_processor/pseries_remove_processor, use
cpu_maps_update_begin()/cpu_maps_update_done() as we're modifying the
cpu_present_map there.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Gautham R Shenoy 2008-01-25 21:08:02 +01:00 • committed by Ingo Molnar
parent d221938c04
commit 86ef5c9a8e
15 changed files with 62 additions and 61 deletions
Download patch file Download diff file Expand all files Collapse all files

16
arch/x86/kernel/microcode.c
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@ -436,7 +436,7 @@ static ssize_t microcode_write (struct file *file, const char __user *buf, size_
return -EINVAL;
}
lock_cpu_hotplug();
get_online_cpus();
mutex_lock(&microcode_mutex);
user_buffer = (void __user *) buf;
@ -447,7 +447,7 @@ static ssize_t microcode_write (struct file *file, const char __user *buf, size_
ret = (ssize_t)len;
mutex_unlock(&microcode_mutex);
unlock_cpu_hotplug();
put_online_cpus();
return ret;
}
@ -658,14 +658,14 @@ static ssize_t reload_store(struct sys_device *dev, const char *buf, size_t sz)
old = current->cpus_allowed;
lock_cpu_hotplug();
get_online_cpus();
set_cpus_allowed(current, cpumask_of_cpu(cpu));
mutex_lock(&microcode_mutex);
if (uci->valid)
err = cpu_request_microcode(cpu);
mutex_unlock(&microcode_mutex);
unlock_cpu_hotplug();
put_online_cpus();
set_cpus_allowed(current, old);
}
if (err)
@ -817,9 +817,9 @@ static int __init microcode_init (void)
return PTR_ERR(microcode_pdev);
}
lock_cpu_hotplug();
get_online_cpus();
error = sysdev_driver_register(&cpu_sysdev_class, &mc_sysdev_driver);
unlock_cpu_hotplug();
put_online_cpus();
if (error) {
microcode_dev_exit();
platform_device_unregister(microcode_pdev);
@ -839,9 +839,9 @@ static void __exit microcode_exit (void)
unregister_hotcpu_notifier(&mc_cpu_notifier);
lock_cpu_hotplug();
get_online_cpus();
sysdev_driver_unregister(&cpu_sysdev_class, &mc_sysdev_driver);
unlock_cpu_hotplug();
put_online_cpus();
platform_device_unregister(microcode_pdev);
}