cpu-hotplug: convert cpu_hotplug_disabled to a counter
As a prerequisite to exporting cpu_hotplug_enable/cpu_hotplug_disable functions to modules we need to convert cpu_hotplug_disabled to a counter to properly support disable -> disable -> enable call sequences. E.g. after Hyper-V vmbus module (which is supposed to be the first user of exported cpu_hotplug_enable/cpu_hotplug_disable) did cpu_hotplug_disable() hibernate path calls disable_nonboot_cpus() and if we hit an error in _cpu_down() enable_nonboot_cpus() will be called on the failure path (thus making cpu_hotplug_disabled = 0 and leaving cpu hotplug in 'enabled' state). Same problem is possible if more than 1 module use cpu_hotplug_disable/cpu_hotplug_enable on their load/unload paths. When one of these modules is been unloaded it is logical to leave cpu hotplug in 'disabled' state. To support the change we need to increse cpu_hotplug_disabled counter in disable_nonboot_cpus() unconditionally as all users of disable_nonboot_cpus() are supposed to do enable_nonboot_cpus() in case an error was returned. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Родитель
54bf725e5d
Коммит
89af7ba574
|
@ -72,7 +72,7 @@ More details follow:
|
|||
|
|
||||
v
|
||||
Disable regular cpu hotplug
|
||||
by setting cpu_hotplug_disabled=1
|
||||
by increasing cpu_hotplug_disabled
|
||||
|
|
||||
v
|
||||
Release cpu_add_remove_lock
|
||||
|
@ -89,7 +89,7 @@ Resuming back is likewise, with the counterparts being (in the order of
|
|||
execution during resume):
|
||||
* enable_nonboot_cpus() which involves:
|
||||
| Acquire cpu_add_remove_lock
|
||||
| Reset cpu_hotplug_disabled to 0, thereby enabling regular cpu hotplug
|
||||
| Decrease cpu_hotplug_disabled, thereby enabling regular cpu hotplug
|
||||
| Call _cpu_up() [for all those cpus in the frozen_cpus mask, in a loop]
|
||||
| Release cpu_add_remove_lock
|
||||
v
|
||||
|
@ -120,7 +120,7 @@ after the entire cycle is complete (i.e., suspend + resume).
|
|||
Acquire cpu_add_remove_lock
|
||||
|
|
||||
v
|
||||
If cpu_hotplug_disabled is 1
|
||||
If cpu_hotplug_disabled > 0
|
||||
return gracefully
|
||||
|
|
||||
|
|
||||
|
|
21
kernel/cpu.c
21
kernel/cpu.c
|
@ -191,14 +191,14 @@ void cpu_hotplug_done(void)
|
|||
void cpu_hotplug_disable(void)
|
||||
{
|
||||
cpu_maps_update_begin();
|
||||
cpu_hotplug_disabled = 1;
|
||||
cpu_hotplug_disabled++;
|
||||
cpu_maps_update_done();
|
||||
}
|
||||
|
||||
void cpu_hotplug_enable(void)
|
||||
{
|
||||
cpu_maps_update_begin();
|
||||
cpu_hotplug_disabled = 0;
|
||||
WARN_ON(--cpu_hotplug_disabled < 0);
|
||||
cpu_maps_update_done();
|
||||
}
|
||||
|
||||
|
@ -608,13 +608,18 @@ int disable_nonboot_cpus(void)
|
|||
}
|
||||
}
|
||||
|
||||
if (!error) {
|
||||
if (!error)
|
||||
BUG_ON(num_online_cpus() > 1);
|
||||
/* Make sure the CPUs won't be enabled by someone else */
|
||||
cpu_hotplug_disabled = 1;
|
||||
} else {
|
||||
else
|
||||
pr_err("Non-boot CPUs are not disabled\n");
|
||||
}
|
||||
|
||||
/*
|
||||
* Make sure the CPUs won't be enabled by someone else. We need to do
|
||||
* this even in case of failure as all disable_nonboot_cpus() users are
|
||||
* supposed to do enable_nonboot_cpus() on the failure path.
|
||||
*/
|
||||
cpu_hotplug_disabled++;
|
||||
|
||||
cpu_maps_update_done();
|
||||
return error;
|
||||
}
|
||||
|
@ -633,7 +638,7 @@ void __ref enable_nonboot_cpus(void)
|
|||
|
||||
/* Allow everyone to use the CPU hotplug again */
|
||||
cpu_maps_update_begin();
|
||||
cpu_hotplug_disabled = 0;
|
||||
WARN_ON(--cpu_hotplug_disabled < 0);
|
||||
if (cpumask_empty(frozen_cpus))
|
||||
goto out;
|
||||
|
||||
|
|
Загрузка…
Ссылка в новой задаче