linux-kernel - [PATCH v3 2/4] sparc64: Migrate hvcons irq to panicked cpu

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Message-Id: <1485977680-203775-3-git-send-email-vijay.ac.kumar@oracle.com>
Date:   Wed,  1 Feb 2017 11:34:38 -0800
From:   Vijay Kumar <vijay.ac.kumar@...cle.com>
To:     davem@...emloft.net
Cc:     sparclinux@...r.kernel.org, karl.volz@...cle.com,
        rob.gardner@...cle.com, linux-kernel@...r.kernel.org,
        vijay.ac.kumar@...cle.com
Subject: [PATCH v3 2/4] sparc64: Migrate hvcons irq to panicked cpu

On panic, all other CPUs are stopped except the one which had
hit panic. To keep console alive, we need to migrate hvcons irq
to panicked CPU.

Signed-off-by: Vijay Kumar <vijay.ac.kumar@...cle.com>
---
v2->v3: Added SERIAL_SUNHV conditional group for
        sunhv_migrate_hvcons_irq().
---
 arch/sparc/include/asm/setup.h |    5 ++++-
 arch/sparc/kernel/smp_64.c     |    6 +++++-
 drivers/tty/serial/sunhv.c     |    6 ++++++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/sparc/include/asm/setup.h b/arch/sparc/include/asm/setup.h
index 29d64b1..478bf6b 100644
--- a/arch/sparc/include/asm/setup.h
+++ b/arch/sparc/include/asm/setup.h
@@ -59,8 +59,11 @@ static inline int con_is_present(void)
 extern atomic_t dcpage_flushes_xcall;
 
 extern int sysctl_tsb_ratio;
-#endif
 
+#ifdef CONFIG_SERIAL_SUNHV
+void sunhv_migrate_hvcons_irq(int cpu);
+#endif
+#endif
 void sun_do_break(void);
 extern int stop_a_enabled;
 extern int scons_pwroff;
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index 712bf1b..90a02cb 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -1452,8 +1452,12 @@ void smp_send_stop(void)
 	int cpu;
 
 	if (tlb_type == hypervisor) {
+		int this_cpu = smp_processor_id();
+#ifdef CONFIG_SERIAL_SUNHV
+		sunhv_migrate_hvcons_irq(this_cpu);
+#endif
 		for_each_online_cpu(cpu) {
-			if (cpu == smp_processor_id())
+			if (cpu == this_cpu)
 				continue;
 
 			set_cpu_online(cpu, false);
diff --git a/drivers/tty/serial/sunhv.c b/drivers/tty/serial/sunhv.c
index 99ef5c6..039ae05 100644
--- a/drivers/tty/serial/sunhv.c
+++ b/drivers/tty/serial/sunhv.c
@@ -398,6 +398,12 @@ static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
 
 static struct uart_port *sunhv_port;
 
+void sunhv_migrate_hvcons_irq(int cpu)
+{
+	/* Migrate hvcons irq to param cpu */
+	irq_force_affinity(sunhv_port->irq, cpumask_of(cpu));
+}
+
 /* Copy 's' into the con_write_page, decoding "\n" into
  * "\r\n" along the way.  We have to return two lengths
  * because the caller needs to know how much to advance
-- 
1.7.1