From 64038f292a1b33c7d46bd11f62f7798101152c00 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 15 Nov 2015 20:33:11 +0100 Subject: stop_machine: Fix possible cpu_stopper_thread() crash stop_one_cpu_nowait(fn) will crash the kernel if the callback returns nonzero, work->done == NULL in this case. This needs more cleanups, cpu_stop_signal_done() is called right after we check done != NULL and it does the same check. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Acked-by: Tejun Heo Cc: Linus Torvalds Cc: Mike Galbraith Cc: Milos Vyletel Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20151115193311.GA8242@redhat.com Signed-off-by: Ingo Molnar --- kernel/stop_machine.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/stop_machine.c') diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 867bc20e1ef1..1a66a9569915 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -454,7 +454,7 @@ repeat: preempt_disable(); ret = fn(arg); - if (ret) + if (ret && done) done->ret = ret; /* restore preemption and check it's still balanced */ -- cgit v1.3-18-gd494 From 6a19005157c464b47b2082f2617d12bc11198a0d Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 15 Nov 2015 20:33:14 +0100 Subject: stop_machine: Don't disable preemption in stop_two_cpus() Now that stop_two_cpus() path does not check cpu_active() we can remove preempt_disable(), it was only needed to ensure that stop_machine() can not be called after we observe cpu_active() == T and before we queue the new work. Also, turn the pointless and confusing ->executed check into WARN_ON(). We know that both works must be executed, otherwise we have a bug. And in fact I think that done->executed should die, see the next changes. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Acked-by: Tejun Heo Cc: Linus Torvalds Cc: Mike Galbraith Cc: Milos Vyletel Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20151115193314.GA8249@redhat.com Signed-off-by: Ingo Molnar --- kernel/stop_machine.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) (limited to 'kernel/stop_machine.c') diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 1a66a9569915..17f01a9dc3df 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -258,7 +258,6 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void * struct cpu_stop_work work1, work2; struct multi_stop_data msdata; - preempt_disable(); msdata = (struct multi_stop_data){ .fn = fn, .data = arg, @@ -277,16 +276,12 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void * if (cpu1 > cpu2) swap(cpu1, cpu2); - if (cpu_stop_queue_two_works(cpu1, &work1, cpu2, &work2)) { - preempt_enable(); + if (cpu_stop_queue_two_works(cpu1, &work1, cpu2, &work2)) return -ENOENT; - } - - preempt_enable(); wait_for_completion(&done.completion); - - return done.executed ? done.ret : -ENOENT; + WARN_ON(!done.executed); + return done.ret; } /** -- cgit v1.3-18-gd494 From 1b034bd989aa4a396c13d305759c376c52595a97 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 17 Nov 2015 18:05:23 +0100 Subject: stop_machine: Make cpu_stop_queue_work() and stop_one_cpu_nowait() return bool Change cpu_stop_queue_work() to return true if the work was queued and change stop_one_cpu_nowait() to return the result of cpu_stop_queue_work(). This makes it more useful, for example now you can alloc cpu_stop_work for stop_one_cpu_nowait() and free it in the callback or if stop_one_cpu_nowait() fails, currently this is impossible because you can't know if @fn will be called or not. Also, this allows to kill cpu_stop_done->executed, see the next changes. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Acked-by: Tejun Heo Cc: Linus Torvalds Cc: Mike Galbraith Cc: Milos Vyletel Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20151117170523.GA13955@redhat.com Signed-off-by: Ingo Molnar --- include/linux/stop_machine.h | 7 +++++-- kernel/stop_machine.c | 16 ++++++++++++---- 2 files changed, 17 insertions(+), 6 deletions(-) (limited to 'kernel/stop_machine.c') diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h index 0adedca24c5b..9ef42e1f0b3a 100644 --- a/include/linux/stop_machine.h +++ b/include/linux/stop_machine.h @@ -29,7 +29,7 @@ struct cpu_stop_work { int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg); int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg); -void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, +bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, struct cpu_stop_work *work_buf); int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); @@ -65,7 +65,7 @@ static void stop_one_cpu_nowait_workfn(struct work_struct *work) preempt_enable(); } -static inline void stop_one_cpu_nowait(unsigned int cpu, +static inline bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, struct cpu_stop_work *work_buf) { @@ -74,7 +74,10 @@ static inline void stop_one_cpu_nowait(unsigned int cpu, work_buf->fn = fn; work_buf->arg = arg; schedule_work(&work_buf->work); + return true; } + + return false; } static inline int stop_cpus(const struct cpumask *cpumask, diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 17f01a9dc3df..0ec1f16da379 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -81,17 +81,21 @@ static void __cpu_stop_queue_work(struct cpu_stopper *stopper, } /* queue @work to @stopper. if offline, @work is completed immediately */ -static void cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work) +static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work) { struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu); unsigned long flags; + bool enabled; spin_lock_irqsave(&stopper->lock, flags); - if (stopper->enabled) + enabled = stopper->enabled; + if (enabled) __cpu_stop_queue_work(stopper, work); else cpu_stop_signal_done(work->done, false); spin_unlock_irqrestore(&stopper->lock, flags); + + return enabled; } /** @@ -297,12 +301,16 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void * * * CONTEXT: * Don't care. + * + * RETURNS: + * true if cpu_stop_work was queued successfully and @fn will be called, + * false otherwise. */ -void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, +bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, struct cpu_stop_work *work_buf) { *work_buf = (struct cpu_stop_work){ .fn = fn, .arg = arg, }; - cpu_stop_queue_work(cpu, work_buf); + return cpu_stop_queue_work(cpu, work_buf); } /* static data for stop_cpus */ -- cgit v1.3-18-gd494 From 958c5f848e17e216df138cc2161b07b7120e2d15 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 15 Nov 2015 20:33:20 +0100 Subject: stop_machine: Change stop_one_cpu() to rely on cpu_stop_queue_work() Change stop_one_cpu() to return -ENOENT if cpu_stop_queue_work() fails. Otherwise we know that ->executed must be true after wait_for_completion() so we can just return done.ret. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Acked-by: Tejun Heo Cc: Linus Torvalds Cc: Mike Galbraith Cc: Milos Vyletel Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20151115193320.GA8259@redhat.com Signed-off-by: Ingo Molnar --- kernel/stop_machine.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'kernel/stop_machine.c') diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 0ec1f16da379..68b73c400408 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -128,9 +128,11 @@ int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg) struct cpu_stop_work work = { .fn = fn, .arg = arg, .done = &done }; cpu_stop_init_done(&done, 1); - cpu_stop_queue_work(cpu, &work); + if (!cpu_stop_queue_work(cpu, &work)) + return -ENOENT; wait_for_completion(&done.completion); - return done.executed ? done.ret : -ENOENT; + WARN_ON(!done.executed); + return done.ret; } /* This controls the threads on each CPU. */ -- cgit v1.3-18-gd494 From 4aff1ca6970afbf9cd916c34a9c442c8ccba905e Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 15 Nov 2015 20:33:23 +0100 Subject: stop_machine: Change __stop_cpus() to rely on cpu_stop_queue_work() Change queue_stop_cpus_work() to return true if it queues at least one work, this means that the caller should wait. __stop_cpus() can check the value returned by queue_stop_cpus_work() and avoid done.executed, just like stop_one_cpu() does. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Acked-by: Tejun Heo Cc: Linus Torvalds Cc: Mike Galbraith Cc: Milos Vyletel Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20151115193323.GA8262@redhat.com Signed-off-by: Ingo Molnar --- kernel/stop_machine.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'kernel/stop_machine.c') diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 68b73c400408..ed2019ac192d 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -318,12 +318,13 @@ bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, /* static data for stop_cpus */ static DEFINE_MUTEX(stop_cpus_mutex); -static void queue_stop_cpus_work(const struct cpumask *cpumask, +static bool queue_stop_cpus_work(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg, struct cpu_stop_done *done) { struct cpu_stop_work *work; unsigned int cpu; + bool queued = false; /* * Disable preemption while queueing to avoid getting @@ -336,9 +337,12 @@ static void queue_stop_cpus_work(const struct cpumask *cpumask, work->fn = fn; work->arg = arg; work->done = done; - cpu_stop_queue_work(cpu, work); + if (cpu_stop_queue_work(cpu, work)) + queued = true; } lg_global_unlock(&stop_cpus_lock); + + return queued; } static int __stop_cpus(const struct cpumask *cpumask, @@ -347,9 +351,11 @@ static int __stop_cpus(const struct cpumask *cpumask, struct cpu_stop_done done; cpu_stop_init_done(&done, cpumask_weight(cpumask)); - queue_stop_cpus_work(cpumask, fn, arg, &done); + if (!queue_stop_cpus_work(cpumask, fn, arg, &done)) + return -ENOENT; wait_for_completion(&done.completion); - return done.executed ? done.ret : -ENOENT; + WARN_ON(!done.executed); + return done.ret; } /** -- cgit v1.3-18-gd494 From 6fa3b826bcb3309157166e6e523a4be236fe267a Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 15 Nov 2015 20:33:26 +0100 Subject: stop_machine: Kill cpu_stop_done->executed Now that cpu_stop_done->executed becomes write-only (ignoring WARN_ON() checks) we can remove it. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Acked-by: Tejun Heo Cc: Linus Torvalds Cc: Mike Galbraith Cc: Milos Vyletel Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20151115193326.GA8269@redhat.com Signed-off-by: Ingo Molnar --- kernel/stop_machine.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) (limited to 'kernel/stop_machine.c') diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index ed2019ac192d..09eb83fc9f0e 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -28,7 +28,6 @@ */ struct cpu_stop_done { atomic_t nr_todo; /* nr left to execute */ - bool executed; /* actually executed? */ int ret; /* collected return value */ struct completion completion; /* fired if nr_todo reaches 0 */ }; @@ -63,11 +62,9 @@ static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo) } /* signal completion unless @done is NULL */ -static void cpu_stop_signal_done(struct cpu_stop_done *done, bool executed) +static void cpu_stop_signal_done(struct cpu_stop_done *done) { if (done) { - if (executed) - done->executed = true; if (atomic_dec_and_test(&done->nr_todo)) complete(&done->completion); } @@ -92,7 +89,7 @@ static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work) if (enabled) __cpu_stop_queue_work(stopper, work); else - cpu_stop_signal_done(work->done, false); + cpu_stop_signal_done(work->done); spin_unlock_irqrestore(&stopper->lock, flags); return enabled; @@ -131,7 +128,6 @@ int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg) if (!cpu_stop_queue_work(cpu, &work)) return -ENOENT; wait_for_completion(&done.completion); - WARN_ON(!done.executed); return done.ret; } @@ -286,7 +282,6 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void * return -ENOENT; wait_for_completion(&done.completion); - WARN_ON(!done.executed); return done.ret; } @@ -354,7 +349,6 @@ static int __stop_cpus(const struct cpumask *cpumask, if (!queue_stop_cpus_work(cpumask, fn, arg, &done)) return -ENOENT; wait_for_completion(&done.completion); - WARN_ON(!done.executed); return done.ret; } @@ -467,6 +461,7 @@ repeat: ret = fn(arg); if (ret && done) done->ret = ret; + cpu_stop_signal_done(done); /* restore preemption and check it's still balanced */ preempt_enable(); @@ -475,7 +470,6 @@ repeat: kallsyms_lookup((unsigned long)fn, NULL, NULL, NULL, ksym_buf), arg); - cpu_stop_signal_done(done, true); goto repeat; } } -- cgit v1.3-18-gd494 From dd2e3121e3cb16d03a6e3f2db48f260f046f39c2 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 15 Nov 2015 20:33:29 +0100 Subject: stop_machine: Shift the 'done != NULL' check from cpu_stop_signal_done() to callers Change cpu_stop_queue_work() and cpu_stopper_thread() to check done != NULL before cpu_stop_signal_done(done). This makes the code more clean imo, note that cpu_stopper_thread() has to do this check anyway. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Acked-by: Tejun Heo Cc: Linus Torvalds Cc: Mike Galbraith Cc: Milos Vyletel Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20151115193329.GA8274@redhat.com Signed-off-by: Ingo Molnar --- kernel/stop_machine.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) (limited to 'kernel/stop_machine.c') diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 09eb83fc9f0e..7ff7acee2c76 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -64,10 +64,8 @@ static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo) /* signal completion unless @done is NULL */ static void cpu_stop_signal_done(struct cpu_stop_done *done) { - if (done) { - if (atomic_dec_and_test(&done->nr_todo)) - complete(&done->completion); - } + if (atomic_dec_and_test(&done->nr_todo)) + complete(&done->completion); } static void __cpu_stop_queue_work(struct cpu_stopper *stopper, @@ -88,7 +86,7 @@ static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work) enabled = stopper->enabled; if (enabled) __cpu_stop_queue_work(stopper, work); - else + else if (work->done) cpu_stop_signal_done(work->done); spin_unlock_irqrestore(&stopper->lock, flags); @@ -457,12 +455,12 @@ repeat: /* cpu stop callbacks are not allowed to sleep */ preempt_disable(); - ret = fn(arg); - if (ret && done) - done->ret = ret; - cpu_stop_signal_done(done); - + if (done) { + if (ret) + done->ret = ret; + cpu_stop_signal_done(done); + } /* restore preemption and check it's still balanced */ preempt_enable(); WARN_ONCE(preempt_count(), -- cgit v1.3-18-gd494 From accaf6ea3db6f5fb997f096b6eefd5431d03f7e5 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 15 Nov 2015 20:33:32 +0100 Subject: stop_machine: Clean up the usage of the preemption counter in cpu_stopper_thread() 1. Change this code to use preempt_count_inc/preempt_count_dec; this way it works even if CONFIG_PREEMPT_COUNT=n, and we avoid the unnecessary __preempt_schedule() check (stop_sched_class is not preemptible). And this makes clear that we only want to make preempt_count() != 0 for __might_sleep() / schedule_debug(). 2. Change WARN_ONCE() to use %pf to print the function name and remove kallsyms_lookup/ksym_buf. 3. Move "int ret" into the "if (work)" block, this looks more consistent. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Acked-by: Tejun Heo Cc: Linus Torvalds Cc: Mike Galbraith Cc: Milos Vyletel Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20151115193332.GA8281@redhat.com Signed-off-by: Ingo Molnar --- kernel/stop_machine.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) (limited to 'kernel/stop_machine.c') diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 7ff7acee2c76..61101193967e 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -435,7 +435,6 @@ static void cpu_stopper_thread(unsigned int cpu) { struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu); struct cpu_stop_work *work; - int ret; repeat: work = NULL; @@ -451,23 +450,19 @@ repeat: cpu_stop_fn_t fn = work->fn; void *arg = work->arg; struct cpu_stop_done *done = work->done; - char ksym_buf[KSYM_NAME_LEN] __maybe_unused; + int ret; - /* cpu stop callbacks are not allowed to sleep */ - preempt_disable(); + /* cpu stop callbacks must not sleep, make in_atomic() == T */ + preempt_count_inc(); ret = fn(arg); if (done) { if (ret) done->ret = ret; cpu_stop_signal_done(done); } - /* restore preemption and check it's still balanced */ - preempt_enable(); + preempt_count_dec(); WARN_ONCE(preempt_count(), - "cpu_stop: %s(%p) leaked preempt count\n", - kallsyms_lookup((unsigned long)fn, NULL, NULL, NULL, - ksym_buf), arg); - + "cpu_stop: %pf(%p) leaked preempt count\n", fn, arg); goto repeat; } } -- cgit v1.3-18-gd494 From 86fffe4a61dd972d5a4e23260d530be6da02f614 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 11 Dec 2015 13:40:46 -0800 Subject: 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 Acked-by: Ingo Molnar Cc: "Paul E. McKenney" Cc: Pranith Kumar Cc: Michal Hocko Cc: Vladimir Davydov Cc: Johannes Weiner Cc: H. Peter Anvin Cc: Tejun Heo Cc: Iulia Manda Cc: Andy Lutomirski Cc: Rusty Russell Cc: Peter Zijlstra Cc: Chuck Ebbert Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/stop_machine.h | 6 +++--- init/Kconfig | 7 ------- kernel/stop_machine.c | 4 ++-- 3 files changed, 5 insertions(+), 12 deletions(-) (limited to 'kernel/stop_machine.c') 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 */ -- cgit v1.3-18-gd494 From b493c34309cb4aebc44272897067ebf54cb07271 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Fri, 15 Jan 2016 16:58:16 -0800 Subject: kernel/stop_machine.c: remove CONFIG_SMP dependencies stop_machine.o is only built if CONFIG_SMP=y, so this ifdef always evaluates to true. [akpm@linux-foundation.org: remove now-unneeded ifdef] Reported-by: Valentin Rothberg Cc: Chris Wilson Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/stop_machine.c | 4 ---- 1 file changed, 4 deletions(-) (limited to 'kernel/stop_machine.c') diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index edb6de4f5908..a467e6c28a3b 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -529,8 +529,6 @@ static int __init cpu_stop_init(void) } early_initcall(cpu_stop_init); -#if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU) - static int __stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus) { struct multi_stop_data msdata = { @@ -628,5 +626,3 @@ int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data, mutex_unlock(&stop_cpus_mutex); return ret ?: done.ret; } - -#endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */ -- cgit v1.3-18-gd494