* [PATCH v3 1/2] cpu-hotplug: export cpu_hotplug_enable/cpu_hotplug_disable
2015-06-02 12:04 [PATCH v3 0/2] Drivers: hv: vmbus: use cpu_hotplug_enable/disable for CPU offlining prevention Vitaly Kuznetsov
@ 2015-06-02 12:04 ` Vitaly Kuznetsov
2015-06-02 12:04 ` [PATCH v3 2/2] Drivers: hv: vmbus: use cpu_hotplug_enable/disable Vitaly Kuznetsov
1 sibling, 0 replies; 3+ messages in thread
From: Vitaly Kuznetsov @ 2015-06-02 12:04 UTC (permalink / raw)
To: devel
Cc: K. Y. Srinivasan, Haiyang Zhang, linux-kernel, Dexuan Cui,
Ingo Molnar, Paul E. McKenney, Rafael J. Wysocki, Peter Zijlstra,
Thomas Gleixner, Radim Krčmář
Loaded Hyper-V module will use these functions to disable CPU hotplug
under certain circumstances. Convert cpu_hotplug_disabled to a counter
(protected by cpu_add_remove_lock) to support e.g. disable -> disable ->
enable call sequences.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
Documentation/power/suspend-and-cpuhotplug.txt | 6 +++---
kernel/cpu.c | 13 ++++++++-----
2 files changed, 11 insertions(+), 8 deletions(-)
diff --git a/Documentation/power/suspend-and-cpuhotplug.txt b/Documentation/power/suspend-and-cpuhotplug.txt
index 2850df3..2fc9095 100644
--- a/Documentation/power/suspend-and-cpuhotplug.txt
+++ b/Documentation/power/suspend-and-cpuhotplug.txt
@@ -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
|
|
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 94bbe46..8f35ee6 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -190,17 +190,19 @@ 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();
}
+EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
void cpu_hotplug_enable(void)
{
cpu_maps_update_begin();
- cpu_hotplug_disabled = 0;
+ if (cpu_hotplug_disabled)
+ cpu_hotplug_disabled--;
cpu_maps_update_done();
}
-
+EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
#endif /* CONFIG_HOTPLUG_CPU */
/* Need to know about CPUs going up/down? */
@@ -600,7 +602,7 @@ int disable_nonboot_cpus(void)
if (!error) {
BUG_ON(num_online_cpus() > 1);
/* Make sure the CPUs won't be enabled by someone else */
- cpu_hotplug_disabled = 1;
+ cpu_hotplug_disabled++;
} else {
pr_err("Non-boot CPUs are not disabled\n");
}
@@ -622,7 +624,8 @@ void __ref enable_nonboot_cpus(void)
/* Allow everyone to use the CPU hotplug again */
cpu_maps_update_begin();
- cpu_hotplug_disabled = 0;
+ if (cpu_hotplug_disabled)
+ cpu_hotplug_disabled--;
if (cpumask_empty(frozen_cpus))
goto out;
--
1.9.3
^ permalink raw reply [flat|nested] 3+ messages in thread* [PATCH v3 2/2] Drivers: hv: vmbus: use cpu_hotplug_enable/disable
2015-06-02 12:04 [PATCH v3 0/2] Drivers: hv: vmbus: use cpu_hotplug_enable/disable for CPU offlining prevention Vitaly Kuznetsov
2015-06-02 12:04 ` [PATCH v3 1/2] cpu-hotplug: export cpu_hotplug_enable/cpu_hotplug_disable Vitaly Kuznetsov
@ 2015-06-02 12:04 ` Vitaly Kuznetsov
1 sibling, 0 replies; 3+ messages in thread
From: Vitaly Kuznetsov @ 2015-06-02 12:04 UTC (permalink / raw)
To: devel
Cc: K. Y. Srinivasan, Haiyang Zhang, linux-kernel, Dexuan Cui,
Ingo Molnar, Paul E. McKenney, Rafael J. Wysocki, Peter Zijlstra,
Thomas Gleixner, Radim Krčmář
Commit e513229b4c38 ("Drivers: hv: vmbus: prevent cpu offlining on newer
hypervisors") was altering smp_ops.cpu_disable to prevent CPU offlining.
We can bo better by using cpu_hotplug_enable/disable functions instead of
such hard-coding.
Reported-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
drivers/hv/vmbus_drv.c | 38 ++++----------------------------------
1 file changed, 4 insertions(+), 34 deletions(-)
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index cf20400..6de65fb 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -763,38 +763,6 @@ static void vmbus_isr(void)
}
}
-#ifdef CONFIG_HOTPLUG_CPU
-static int hyperv_cpu_disable(void)
-{
- return -ENOSYS;
-}
-
-static void hv_cpu_hotplug_quirk(bool vmbus_loaded)
-{
- static void *previous_cpu_disable;
-
- /*
- * Offlining a CPU when running on newer hypervisors (WS2012R2, Win8,
- * ...) is not supported at this moment as channel interrupts are
- * distributed across all of them.
- */
-
- if ((vmbus_proto_version == VERSION_WS2008) ||
- (vmbus_proto_version == VERSION_WIN7))
- return;
-
- if (vmbus_loaded) {
- previous_cpu_disable = smp_ops.cpu_disable;
- smp_ops.cpu_disable = hyperv_cpu_disable;
- pr_notice("CPU offlining is not supported by hypervisor\n");
- } else if (previous_cpu_disable)
- smp_ops.cpu_disable = previous_cpu_disable;
-}
-#else
-static void hv_cpu_hotplug_quirk(bool vmbus_loaded)
-{
-}
-#endif
/*
* vmbus_bus_init -Main vmbus driver initialization routine.
@@ -836,7 +804,8 @@ static int vmbus_bus_init(int irq)
if (ret)
goto err_alloc;
- hv_cpu_hotplug_quirk(true);
+ if (vmbus_proto_version > VERSION_WIN7)
+ cpu_hotplug_disable();
/*
* Only register if the crash MSRs are available
@@ -1121,7 +1090,8 @@ static void __exit vmbus_exit(void)
smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1);
}
acpi_bus_unregister_driver(&vmbus_acpi_driver);
- hv_cpu_hotplug_quirk(false);
+ if (vmbus_proto_version > VERSION_WIN7)
+ cpu_hotplug_enable();
}
--
1.9.3
^ permalink raw reply [flat|nested] 3+ messages in thread