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authorChris Wilson <chris@chris-wilson.co.uk>2015-12-11 13:40:46 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-12-12 10:15:34 -0800
commit86fffe4a61dd972d5a4e23260d530be6da02f614 (patch)
tree60727aa79cbed733cee2343417bcba5bd6b0d6c4
parent98e89cf02aed11166698dd53c6f14865613babb3 (diff)
downloadlinux-86fffe4a61dd972d5a4e23260d530be6da02f614.tar.gz
kernel: remove stop_machine() Kconfig dependency
Currently the full stop_machine() routine is only enabled on SMP if module unloading is enabled, or if the CPUs are hotpluggable. This leads to configurations where stop_machine() is broken as it will then only run the callback on the local CPU with irqs disabled, and not stop the other CPUs or run the callback on them. For example, this breaks MTRR setup on x86 in certain configs since ea8596bb2d8d379 ("kprobes/x86: Remove unused text_poke_smp() and text_poke_smp_batch() functions") as the MTRR is only established on the boot CPU. This patch removes the Kconfig option for STOP_MACHINE and uses the SMP and HOTPLUG_CPU config options to compile the correct stop_machine() for the architecture, removing the false dependency on MODULE_UNLOAD in the process. Link: https://lkml.org/lkml/2014/10/8/124 References: https://bugs.freedesktop.org/show_bug.cgi?id=84794 Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Pranith Kumar <bobby.prani@gmail.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: H. Peter Anvin <hpa@linux.intel.com> Cc: Tejun Heo <tj@kernel.org> Cc: Iulia Manda <iulia.manda21@gmail.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Chuck Ebbert <cebbert.lkml@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/stop_machine.h6
-rw-r--r--init/Kconfig7
-rw-r--r--kernel/stop_machine.c4
3 files changed, 5 insertions, 12 deletions
diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h
index 0adedca24c5b..0e1b1540597a 100644
--- a/include/linux/stop_machine.h
+++ b/include/linux/stop_machine.h
@@ -99,7 +99,7 @@ static inline int try_stop_cpus(const struct cpumask *cpumask,
* grabbing every spinlock (and more). So the "read" side to such a
* lock is anything which disables preemption.
*/
-#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
+#if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
/**
* stop_machine: freeze the machine on all CPUs and run this function
@@ -118,7 +118,7 @@ int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
const struct cpumask *cpus);
-#else /* CONFIG_STOP_MACHINE && CONFIG_SMP */
+#else /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
static inline int stop_machine(cpu_stop_fn_t fn, void *data,
const struct cpumask *cpus)
@@ -137,5 +137,5 @@ static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
return stop_machine(fn, data, cpus);
}
-#endif /* CONFIG_STOP_MACHINE && CONFIG_SMP */
+#endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
#endif /* _LINUX_STOP_MACHINE */
diff --git a/init/Kconfig b/init/Kconfig
index c24b6f767bf0..235c7a2c0d20 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -2030,13 +2030,6 @@ config INIT_ALL_POSSIBLE
it was better to provide this option than to break all the archs
and have several arch maintainers pursuing me down dark alleys.
-config STOP_MACHINE
- bool
- default y
- depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
- help
- Need stop_machine() primitive.
-
source "block/Kconfig"
config PREEMPT_NOTIFIERS
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 867bc20e1ef1..a3bbaee77c58 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -531,7 +531,7 @@ static int __init cpu_stop_init(void)
}
early_initcall(cpu_stop_init);
-#ifdef CONFIG_STOP_MACHINE
+#if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
static int __stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus)
{
@@ -631,4 +631,4 @@ int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
return ret ?: done.ret;
}
-#endif /* CONFIG_STOP_MACHINE */
+#endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */