linux-kernel - [PATCH v4 08/17] arm64: hibernate.c: Create a new function to handle cpu_up(sleep

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Message-Id: <20200323135110.30522-9-qais.yousef@arm.com>
Date:   Mon, 23 Mar 2020 13:51:01 +0000
From:   Qais Yousef <qais.yousef@....com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, Qais Yousef <qais.yousef@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Steve Capper <steve.capper@....com>,
        Richard Fontana <rfontana@...hat.com>,
        James Morse <james.morse@....com>,
        Mark Rutland <mark.rutland@....com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Ingo Molnar <mingo@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Jiri Kosina <jkosina@...e.cz>,
        Pavankumar Kondeti <pkondeti@...eaurora.org>,
        Zhenzhong Duan <zhenzhong.duan@...cle.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH v4 08/17] arm64: hibernate.c: Create a new function to handle cpu_up(sleep_cpu)

In preparation to make cpu_up/down private - move the user in arm64
hibernate.c to use a new generic function that provides what arm64
needs.

Acked-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Qais Yousef <qais.yousef@....com>
CC: Catalin Marinas <catalin.marinas@....com>
CC: Will Deacon <will@...nel.org>
CC: Steve Capper <steve.capper@....com>
CC: Richard Fontana <rfontana@...hat.com>
CC: James Morse <james.morse@....com>
CC: Mark Rutland <mark.rutland@....com>
CC: Thomas Gleixner <tglx@...utronix.de>
CC: Josh Poimboeuf <jpoimboe@...hat.com>
CC: Ingo Molnar <mingo@...nel.org>
CC: "Peter Zijlstra (Intel)" <peterz@...radead.org>
CC: Nicholas Piggin <npiggin@...il.com>
CC: Daniel Lezcano <daniel.lezcano@...aro.org>
CC: Jiri Kosina <jkosina@...e.cz>
CC: Pavankumar Kondeti <pkondeti@...eaurora.org>
CC: Zhenzhong Duan <zhenzhong.duan@...cle.com>
CC: linux-arm-kernel@...ts.infradead.org
CC: linux-kernel@...r.kernel.org
---
 arch/arm64/kernel/hibernate.c | 13 +++++--------
 include/linux/cpu.h           |  1 +
 kernel/cpu.c                  | 24 ++++++++++++++++++++++++
 3 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index 590963c9c609..5b73e92c99e3 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -166,14 +166,11 @@ int arch_hibernation_header_restore(void *addr)
 		sleep_cpu = -EINVAL;
 		return -EINVAL;
 	}
-	if (!cpu_online(sleep_cpu)) {
-		pr_info("Hibernated on a CPU that is offline! Bringing CPU up.\n");
-		ret = cpu_up(sleep_cpu);
-		if (ret) {
-			pr_err("Failed to bring hibernate-CPU up!\n");
-			sleep_cpu = -EINVAL;
-			return ret;
-		}
+
+	ret = bringup_hibernate_cpu(sleep_cpu);
+	if (ret) {
+		sleep_cpu = -EINVAL;
+		return ret;
 	}
 
 	resume_hdr = *hdr;
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 64a246e9c8db..aebe8186cb07 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -93,6 +93,7 @@ int add_cpu(unsigned int cpu);
 void notify_cpu_starting(unsigned int cpu);
 extern void cpu_maps_update_begin(void);
 extern void cpu_maps_update_done(void);
+extern int bringup_hibernate_cpu(unsigned int sleep_cpu);
 
 #else	/* CONFIG_SMP */
 #define cpuhp_tasks_frozen	0
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 03c727195b65..bf39c5bfb6d9 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1275,6 +1275,30 @@ int add_cpu(unsigned int cpu)
 }
 EXPORT_SYMBOL_GPL(add_cpu);
 
+/**
+ * bringup_hibernate_cpu - Bring up the CPU that we hibernated on
+ * @sleep_cpu: The cpu we hibernated on and should be brought up.
+ *
+ * On some archs like arm64, we can hibernate on any CPU, but on wake up the
+ * CPU we hibernated on might be offline as a side effect of using maxcpus= for
+ * example.
+ */
+int bringup_hibernate_cpu(unsigned int sleep_cpu)
+{
+	int ret;
+
+	if (!cpu_online(sleep_cpu)) {
+		pr_info("Hibernated on a CPU that is offline! Bringing CPU up.\n");
+		ret = cpu_up(sleep_cpu);
+		if (ret) {
+			pr_err("Failed to bring hibernate-CPU up!\n");
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
 #ifdef CONFIG_PM_SLEEP_SMP
 static cpumask_var_t frozen_cpus;
 
-- 
2.17.1