* [PATCH v3 01/15] cpu: Add new {add,remove}_cpu() functions
[not found] <20200223192942.18420-1-qais.yousef@arm.com>
@ 2020-02-23 19:29 ` Qais Yousef
2020-02-23 19:29 ` [PATCH v3 10/15] parisc: Replace cpu_up/down with add/remove_cpu Qais Yousef
1 sibling, 0 replies; 2+ messages in thread
From: Qais Yousef @ 2020-02-23 19:29 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Paul E . McKenney, Qais Yousef, Helge Deller, Michael Ellerman,
David S. Miller, Juergen Gross, Mark Rutland, Lorenzo Pieralisi,
xen-devel, linux-parisc, sparclinux, linuxppc-dev,
linux-arm-kernel, x86, linux-kernel
The new functions use device_{online,offline}() which are userspace
safe.
This is in preparation to move cpu_{up, down} kernel users to use
a safer interface that is not racy with userspace.
Suggested-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: "Paul E. McKenney" <paulmck@kernel.org>
CC: Helge Deller <deller@gmx.de>
CC: Michael Ellerman <mpe@ellerman.id.au>
CC: "David S. Miller" <davem@davemloft.net>
CC: Juergen Gross <jgross@suse.com>
CC: Mark Rutland <mark.rutland@arm.com>
CC: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
CC: xen-devel@lists.xenproject.org
CC: linux-parisc@vger.kernel.org
CC: sparclinux@vger.kernel.org
CC: linuxppc-dev@lists.ozlabs.org
CC: linux-arm-kernel@lists.infradead.org
CC: x86@kernel.org
CC: linux-kernel@vger.kernel.org
---
include/linux/cpu.h | 2 ++
kernel/cpu.c | 24 ++++++++++++++++++++++++
2 files changed, 26 insertions(+)
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 1ca2baf817ed..cf8cf38dca43 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -89,6 +89,7 @@ extern ssize_t arch_cpu_release(const char *, size_t);
#ifdef CONFIG_SMP
extern bool cpuhp_tasks_frozen;
int cpu_up(unsigned int cpu);
+int add_cpu(unsigned int cpu);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);
extern void cpu_maps_update_done(void);
@@ -118,6 +119,7 @@ extern void cpu_hotplug_disable(void);
extern void cpu_hotplug_enable(void);
void clear_tasks_mm_cpumask(int cpu);
int cpu_down(unsigned int cpu);
+int remove_cpu(unsigned int cpu);
#else /* CONFIG_HOTPLUG_CPU */
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 9c706af713fb..069802f7010f 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1057,6 +1057,18 @@ int cpu_down(unsigned int cpu)
}
EXPORT_SYMBOL(cpu_down);
+int remove_cpu(unsigned int cpu)
+{
+ int ret;
+
+ lock_device_hotplug();
+ ret = device_offline(get_cpu_device(cpu));
+ unlock_device_hotplug();
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(remove_cpu);
+
#else
#define takedown_cpu NULL
#endif /*CONFIG_HOTPLUG_CPU*/
@@ -1209,6 +1221,18 @@ int cpu_up(unsigned int cpu)
}
EXPORT_SYMBOL_GPL(cpu_up);
+int add_cpu(unsigned int cpu)
+{
+ int ret;
+
+ lock_device_hotplug();
+ ret = device_online(get_cpu_device(cpu));
+ unlock_device_hotplug();
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(add_cpu);
+
#ifdef CONFIG_PM_SLEEP_SMP
static cpumask_var_t frozen_cpus;
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH v3 10/15] parisc: Replace cpu_up/down with add/remove_cpu
[not found] <20200223192942.18420-1-qais.yousef@arm.com>
2020-02-23 19:29 ` [PATCH v3 01/15] cpu: Add new {add,remove}_cpu() functions Qais Yousef
@ 2020-02-23 19:29 ` Qais Yousef
1 sibling, 0 replies; 2+ messages in thread
From: Qais Yousef @ 2020-02-23 19:29 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Paul E . McKenney, Qais Yousef, James E.J. Bottomley,
Helge Deller, Richard Fontana, Armijn Hemel, Greg Kroah-Hartman,
linux-parisc, linux-kernel
The core device API performs extra housekeeping bits that are missing
from directly calling cpu_up/down.
See commit a6717c01ddc2 ("powerpc/rtas: use device model APIs and
serialization during LPM") for an example description of what might go
wrong.
This also prepares to make cpu_up/down a private interface for anything
but the cpu subsystem.
Acked-by: Helge Deller <deller@gmx.de>
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
CC: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
CC: Helge Deller <deller@gmx.de>
CC: Richard Fontana <rfontana@redhat.com>
CC: Armijn Hemel <armijn@tjaldur.nl>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: linux-parisc@vger.kernel.org
CC: linux-kernel@vger.kernel.org
---
Helge, this now uses add_cpu() which you should be CCed on. I wasn't sure if
I can keep your Ack or remove it in this case. Please let me know if you need
more clarification.
arch/parisc/kernel/processor.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/parisc/kernel/processor.c b/arch/parisc/kernel/processor.c
index 13f771f74ee3..7f2d0c0ecc80 100644
--- a/arch/parisc/kernel/processor.c
+++ b/arch/parisc/kernel/processor.c
@@ -212,7 +212,7 @@ static int __init processor_probe(struct parisc_device *dev)
#ifdef CONFIG_SMP
if (cpuid) {
set_cpu_present(cpuid, true);
- cpu_up(cpuid);
+ add_cpu(cpuid);
}
#endif
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
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2020-02-23 19:29 ` [PATCH v3 01/15] cpu: Add new {add,remove}_cpu() functions Qais Yousef
2020-02-23 19:29 ` [PATCH v3 10/15] parisc: Replace cpu_up/down with add/remove_cpu Qais Yousef
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