linux-kernel - [GIT pull] smp/hotplug updates for 4.10

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Date:   Wed, 18 Jan 2017 10:42:48 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
cc:     LKML <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [GIT pull] smp/hotplug updates for 4.10

Linus,

please pull the latest smp-urgent-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git smp-urgent-for-linus

This contains a trivial typo fix and an extension to the core code for
dynamically allocating states in the prepare stage.

The extension is necessary right now because we need a proper way to
unbreak LTTNG, which iscurrently non functional due to the removal of the
notifiers. Surely it's out of tree, but it's widely used by distros.

The simple solution would have been to reserve a state for LTTNG, but I'm
not fond about unused crap in the kernel and the dynamic range, which we
admittedly should have done right away, allows us to remove quite some of
the hardcoded states, i.e. those which have no ordering requirements. So
doing the right thing now is better than having an smaller intermediate
solution which needs to be reworked anyway.
     
Thanks,

	tglx

------------------>
Sedat Dilek (1):
      perf/x86/amd/ibs: Fix typo after cleanup state names in cpu/hotplug

Thomas Gleixner (1):
      cpu/hotplug: Provide dynamic range for prepare stage


 arch/x86/events/amd/ibs.c  |  2 +-
 include/linux/cpuhotplug.h |  2 ++
 kernel/cpu.c               | 22 ++++++++++++++++++----
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
index 05612a2529c8..496e60391fac 100644
--- a/arch/x86/events/amd/ibs.c
+++ b/arch/x86/events/amd/ibs.c
@@ -1010,7 +1010,7 @@ static __init int amd_ibs_init(void)
 	 * all online cpus.
 	 */
 	cpuhp_setup_state(CPUHP_AP_PERF_X86_AMD_IBS_STARTING,
-			  "perf/x86/amd/ibs:STARTING",
+			  "perf/x86/amd/ibs:starting",
 			  x86_pmu_amd_ibs_starting_cpu,
 			  x86_pmu_amd_ibs_dying_cpu);
 
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 20bfefbe7594..d936a0021839 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -74,6 +74,8 @@ enum cpuhp_state {
 	CPUHP_ZCOMP_PREPARE,
 	CPUHP_TIMERS_DEAD,
 	CPUHP_MIPS_SOC_PREPARE,
+	CPUHP_BP_PREPARE_DYN,
+	CPUHP_BP_PREPARE_DYN_END		= CPUHP_BP_PREPARE_DYN + 20,
 	CPUHP_BRINGUP_CPU,
 	CPUHP_AP_IDLE_DEAD,
 	CPUHP_AP_OFFLINE,
diff --git a/kernel/cpu.c b/kernel/cpu.c
index f75c4d031eeb..c47506357519 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1302,10 +1302,24 @@ static int cpuhp_cb_check(enum cpuhp_state state)
  */
 static int cpuhp_reserve_state(enum cpuhp_state state)
 {
-	enum cpuhp_state i;
+	enum cpuhp_state i, end;
+	struct cpuhp_step *step;
 
-	for (i = CPUHP_AP_ONLINE_DYN; i <= CPUHP_AP_ONLINE_DYN_END; i++) {
-		if (!cpuhp_ap_states[i].name)
+	switch (state) {
+	case CPUHP_AP_ONLINE_DYN:
+		step = cpuhp_ap_states + CPUHP_AP_ONLINE_DYN;
+		end = CPUHP_AP_ONLINE_DYN_END;
+		break;
+	case CPUHP_BP_PREPARE_DYN:
+		step = cpuhp_bp_states + CPUHP_BP_PREPARE_DYN;
+		end = CPUHP_BP_PREPARE_DYN_END;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	for (i = state; i <= end; i++, step++) {
+		if (!step->name)
 			return i;
 	}
 	WARN(1, "No more dynamic states available for CPU hotplug\n");
@@ -1323,7 +1337,7 @@ static int cpuhp_store_callbacks(enum cpuhp_state state, const char *name,
 
 	mutex_lock(&cpuhp_state_mutex);
 
-	if (state == CPUHP_AP_ONLINE_DYN) {
+	if (state == CPUHP_AP_ONLINE_DYN || state == CPUHP_BP_PREPARE_DYN) {
 		ret = cpuhp_reserve_state(state);
 		if (ret < 0)
 			goto out;