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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	rt@linutronix.de, Richard Weinberger <richard@nod.at>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [PATCH 02/16] relayfs: Convert to hotplug state machine
Date: Thu, 18 Aug 2016 14:57:17 +0200
Message-ID: <20160818125731.27256-3-bigeasy@linutronix.de> (raw)
In-Reply-To: <20160818125731.27256-1-bigeasy@linutronix.de>

From: Richard Weinberger <richard@nod.at>

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.

Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 include/linux/cpuhotplug.h |  1 +
 include/linux/relay.h      |  6 +++++
 kernel/cpu.c               |  6 +++++
 kernel/relay.c             | 58 +++++++++++-----------------------------------
 4 files changed, 26 insertions(+), 45 deletions(-)

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 9e6d10786e29..4c79f40fcebc 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -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,
diff --git a/include/linux/relay.h b/include/linux/relay.h
index eb295e373b90..ecbb34a382b8 100644
--- a/include/linux/relay.h
+++ b/include/linux/relay.h
@@ -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 */
 
diff --git a/kernel/cpu.c b/kernel/cpu.c
index c10eea6ea4dd..2a11381d5997 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -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
@@ -1267,6 +1268,11 @@ static struct cpuhp_step cpuhp_bp_states[] = {
 		.startup = smpcfd_prepare_cpu,
 		.teardown = smpcfd_dead_cpu,
 	},
+	[CPUHP_RELAY_PREPARE] = {
+		.name = "relay prepare",
+		.startup = relay_prepare_cpu,
+		.teardown = NULL,
+	},
 	[CPUHP_RCUTREE_PREP] = {
 		.name = "RCU-tree prepare",
 		.startup = rcutree_prepare_cpu,
diff --git a/kernel/relay.c b/kernel/relay.c
index ed157378f6cb..fc9b4a4af463 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -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)))
-				continue;
-			buf = relay_open_buf(chan, hotcpu);
-			if (!buf) {
-				printk(KERN_ERR
-					"relay_hotcpu_callback: cpu %d buffer "
-					"creation failed\n", hotcpu);
-				mutex_unlock(&relay_channels_mutex);
-				return notifier_from_errno(-ENOMEM);
-			}
-			*per_cpu_ptr(chan->buf, hotcpu) = buf;
+	mutex_lock(&relay_channels_mutex);
+	list_for_each_entry(chan, &relay_channels, list) {
+		if ((buf = *per_cpu_ptr(chan->buf, cpu)))
+			continue;
+		buf = relay_open_buf(chan, cpu);
+		if (!buf) {
+			pr_err("relay: cpu %d buffer creation failed\n", cpu);
+			mutex_unlock(&relay_channels_mutex);
+			return -ENOMEM;
 		}
-		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;
+		*per_cpu_ptr(chan->buf, cpu) = buf;
 	}
-	return NOTIFY_OK;
+	mutex_unlock(&relay_channels_mutex);
+	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);
-- 
2.9.3

  parent reply index

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-18 12:57 cpu hotplug: convert more drivers Sebastian Andrzej Siewior
2016-08-18 12:57 ` [PATCH 01/16] cpuhotplug: Remove CPU_STARTING and CPU_DYING notifier Sebastian Andrzej Siewior
2016-09-06 15:19   ` [tip:smp/hotplug] cpu/hotplug: " tip-bot for Thomas Gleixner
2016-09-06 16:37   ` tip-bot for Thomas Gleixner
2016-08-18 12:57 ` Sebastian Andrzej Siewior [this message]
2016-09-06 15:20   ` [tip:smp/hotplug] relayfs: Convert to hotplug state machine tip-bot for Richard Weinberger
2016-09-06 16:38   ` tip-bot for Richard Weinberger
2016-08-18 12:57 ` [PATCH 03/16] slab: " Sebastian Andrzej Siewior
2016-08-18 17:08   ` Sebastian Andrzej Siewior
2016-08-23 12:53     ` [PATCH 03/16 v2] " Sebastian Andrzej Siewior
2016-09-06 15:21       ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-09-06 16:38       ` tip-bot for Sebastian Andrzej Siewior
2016-08-18 12:57 ` [PATCH 04/16] slub: " Sebastian Andrzej Siewior
2016-09-06 15:21   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-09-06 16:38   ` tip-bot for Sebastian Andrzej Siewior
2016-08-18 12:57 ` [PATCH 05/16] mm: writeback: " Sebastian Andrzej Siewior
2016-09-06 15:22   ` [tip:smp/hotplug] mm/writeback: " tip-bot for Sebastian Andrzej Siewior
2016-09-06 16:39   ` tip-bot for Sebastian Andrzej Siewior
2016-08-18 12:57 ` [PATCH 06/16] kernel: softirq: " Sebastian Andrzej Siewior
2016-09-06 15:22   ` [tip:smp/hotplug] kernel/softirq: " tip-bot for Sebastian Andrzej Siewior
2016-09-06 16:39   ` tip-bot for Sebastian Andrzej Siewior
2016-08-18 12:57 ` [PATCH 07/16] rcu: rcutorture: " Sebastian Andrzej Siewior
2016-08-18 16:20   ` Paul E. McKenney
2016-08-18 12:57 ` [PATCH 08/16] net: mvneta: " Sebastian Andrzej Siewior
2016-09-06 15:23   ` [tip:smp/hotplug] net/mvneta: " tip-bot for Sebastian Andrzej Siewior
2016-09-06 16:40   ` tip-bot for Sebastian Andrzej Siewior
2016-08-18 12:57 ` [PATCH 09/16] md: raid5: " Sebastian Andrzej Siewior
2016-09-06 15:23   ` [tip:smp/hotplug] md/raid5: " tip-bot for Sebastian Andrzej Siewior
2016-09-06 16:40   ` tip-bot for Sebastian Andrzej Siewior
2016-08-18 12:57 ` [PATCH 10/16] cpuidle: pseries: " Sebastian Andrzej Siewior
2016-08-22 16:09   ` Daniel Lezcano
2016-08-22 19:04     ` Sebastian Andrzej Siewior
2016-08-23 14:16       ` Daniel Lezcano
2016-08-23 16:32         ` Sebastian Andrzej Siewior
2016-08-24  9:09           ` [PATCH 10/16 v2] " Sebastian Andrzej Siewior
2016-09-06 15:24   ` [tip:smp/hotplug] cpuidle/pseries: " tip-bot for Sebastian Andrzej Siewior
2016-09-06 16:41   ` tip-bot for Sebastian Andrzej Siewior
2016-08-18 12:57 ` [PATCH 11/16] cpuidle: powernv: " Sebastian Andrzej Siewior
2016-08-24  9:12   ` Sebastian Andrzej Siewior
2016-09-06 15:24     ` [tip:smp/hotplug] cpuidle/powernv: " tip-bot for Sebastian Andrzej Siewior
2016-09-06 16:41     ` tip-bot for Sebastian Andrzej Siewior
2016-08-18 12:57 ` [PATCH 12/16] cpuidle: coupled: " Sebastian Andrzej Siewior
2016-08-23 14:24   ` Daniel Lezcano
2016-08-24  9:14     ` [PATCH 12/16 v2] " Sebastian Andrzej Siewior
2016-09-06 15:25       ` [tip:smp/hotplug] cpuidle/coupled: " tip-bot for Sebastian Andrzej Siewior
2016-09-06 16:42       ` tip-bot for Sebastian Andrzej Siewior
2016-08-18 12:57 ` [PATCH 13/16] MIPS: BUS: CDMM: " Sebastian Andrzej Siewior
2016-09-06 15:25   ` [tip:smp/hotplug] MIPS/BUS/CDMM: " tip-bot for Sebastian Andrzej Siewior
2016-09-06 16:42   ` tip-bot for Sebastian Andrzej Siewior
2016-08-18 12:57 ` [PATCH 14/16] x86: kvm: " Sebastian Andrzej Siewior
2016-08-18 17:06   ` Paolo Bonzini
2016-09-06 15:25   ` [tip:smp/hotplug] x86/kvm: " tip-bot for Sebastian Andrzej Siewior
2016-09-06 16:43   ` tip-bot for Sebastian Andrzej Siewior
2016-08-18 12:57 ` [PATCH 15/16] powerpc: powermac: " Sebastian Andrzej Siewior
2016-09-06 15:26   ` [tip:smp/hotplug] powerpc/powermac: " tip-bot for Sebastian Andrzej Siewior
2016-09-06 16:43   ` tip-bot for Sebastian Andrzej Siewior
2016-08-18 12:57 ` [PATCH 16/16] powerpc: mmu nohash: " Sebastian Andrzej Siewior
2016-09-06 15:26   ` [tip:smp/hotplug] powerpc/mmu " tip-bot for Sebastian Andrzej Siewior
2016-09-06 16:44   ` tip-bot for Sebastian Andrzej Siewior
2016-08-18 13:40 ` cpu hotplug: convert more drivers Ingo Molnar

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