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Commit e6d4989a authored by Richard Weinberger's avatar Richard Weinberger Committed by Thomas Gleixner
Browse files

relayfs: Convert to hotplug state machine 



Install the callbacks via the state machine. They are installed at run time but
relay_prepare_cpu() does not need to be invoked by the boot CPU because
relay_open() was not yet invoked and there are no pools that need to be created.

Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20160818125731.27256-3-bigeasy@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 017c59c0

include/linux/cpuhotplug.h

+1 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ enum cpuhp_state { 
	CPUHP_PROFILE_PREPARE,

	CPUHP_X2APIC_PREPARE,

	CPUHP_SMPCFD_PREPARE,

	CPUHP_RELAY_PREPARE,

	CPUHP_RCUTREE_PREP,

	CPUHP_NOTIFY_PREPARE,

	CPUHP_TIMERS_DEAD,

include/linux/relay.h

+6 −0
Original line number Diff line number Diff line
@@ -288,5 +288,11 @@ static inline void subbuf_start_reserve(struct rchan_buf *buf, 
 */

extern const struct file_operations relay_file_operations;



#ifdef CONFIG_RELAY

int relay_prepare_cpu(unsigned int cpu);

#else

#define relay_prepare_cpu     NULL

#endif



#endif /* _LINUX_RELAY_H */

kernel/cpu.c

+6 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/tick.h>

#include <linux/irq.h>

#include <linux/smpboot.h>

#include <linux/relay.h>



#include <trace/events/power.h>

#define CREATE_TRACE_POINTS
@@ -1272,6 +1273,11 @@ static struct cpuhp_step cpuhp_bp_states[] = { 
		.startup.single		= smpcfd_prepare_cpu,

		.teardown.single	= smpcfd_dead_cpu,

	},

	[CPUHP_RELAY_PREPARE] = {

		.name			= "relay:prepare",

		.startup.single		= relay_prepare_cpu,

		.teardown.single	= NULL,

	},

	[CPUHP_RCUTREE_PREP] = {

		.name			= "RCU/tree:prepare",

		.startup.single		= rcutree_prepare_cpu,

kernel/relay.c

+13 −45
Original line number Diff line number Diff line
@@ -513,48 +513,25 @@ static void setup_callbacks(struct rchan *chan, 
	chan->cb = cb;

}



/**

 * 	relay_hotcpu_callback - CPU hotplug callback

 * 	@nb: notifier block

 * 	@action: hotplug action to take

 * 	@hcpu: CPU number

 *

 * 	Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)

 */

static int relay_hotcpu_callback(struct notifier_block *nb,

				unsigned long action,

				void *hcpu)

int relay_prepare_cpu(unsigned int cpu)

{

	unsigned int hotcpu = (unsigned long)hcpu;

	struct rchan *chan;

	struct rchan_buf *buf;



	switch(action) {

	case CPU_UP_PREPARE:

	case CPU_UP_PREPARE_FROZEN:

	mutex_lock(&relay_channels_mutex);

	list_for_each_entry(chan, &relay_channels, list) {

			if ((buf = *per_cpu_ptr(chan->buf, hotcpu)))

		if ((buf = *per_cpu_ptr(chan->buf, cpu)))

			continue;

			buf = relay_open_buf(chan, hotcpu);

		buf = relay_open_buf(chan, cpu);

		if (!buf) {

				printk(KERN_ERR

					"relay_hotcpu_callback: cpu %d buffer "

					"creation failed\n", hotcpu);

			pr_err("relay: cpu %d buffer creation failed\n", cpu);

			mutex_unlock(&relay_channels_mutex);

				return notifier_from_errno(-ENOMEM);

			return -ENOMEM;

		}

			*per_cpu_ptr(chan->buf, hotcpu) = buf;

		*per_cpu_ptr(chan->buf, cpu) = buf;

	}

	mutex_unlock(&relay_channels_mutex);

		break;

	case CPU_DEAD:

	case CPU_DEAD_FROZEN:

		/* No need to flush the cpu : will be flushed upon

		 * final relay_flush() call. */

		break;

	}

	return NOTIFY_OK;

	return 0;

}



/**
@@ -1387,12 +1364,3 @@ const struct file_operations relay_file_operations = { 
	.splice_read	= relay_file_splice_read,

};

EXPORT_SYMBOL_GPL(relay_file_operations);
 


static __init int relay_init(void)

{



	hotcpu_notifier(relay_hotcpu_callback, 0);

	return 0;

}



early_initcall(relay_init);