linux-kernel - [PATCH 4/4] RISC-V: Fix non-smp kernel boot on SMP systems

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Date:   Mon,  3 Dec 2018 12:57:31 -0800
From:   Atish Patra <atish.patra@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Atish Patra <atish.patra@....com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        devicetree@...r.kernel.org,
        Dmitriy Cherkasov <dmitriy@...-tech.org>,
        linux-riscv@...ts.infradead.org,
        Mark Rutland <mark.rutland@....com>,
        Palmer Dabbelt <palmer@...ive.com>,
        Rob Herring <robh+dt@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Anup Patel <anup@...infault.org>,
        Damien Le Moal <Damien.LeMoal@....com>
Subject: [PATCH 4/4] RISC-V: Fix non-smp kernel boot on SMP systems

Currently, clocksource registration happens for an invalid cpu
for non-smp kernels. This lead to kernel panic as cpu hotplug
registration will fail for those cpus.

Do not proceed if hartid is invalid. Take this opprtunity to
print appropriate error strings for different failure cases.

Signed-off-by: Atish Patra <atish.patra@....com>
---
 drivers/clocksource/riscv_timer.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/riscv_timer.c b/drivers/clocksource/riscv_timer.c
index 39de6e49..4af4af47 100644
--- a/drivers/clocksource/riscv_timer.c
+++ b/drivers/clocksource/riscv_timer.c
@@ -108,6 +108,8 @@ static int __init riscv_timer_init_dt(struct device_node *n)
 	int cpuid, hartid, error;
 
 	hartid = riscv_of_processor_hartid(n);
+	if (hartid < 0)
+		return hartid;
 	cpuid = riscv_hartid_to_cpuid(hartid);
 
 	if (cpuid != smp_processor_id())
@@ -115,14 +117,19 @@ static int __init riscv_timer_init_dt(struct device_node *n)
 
 	/* This should be called only for boot cpu */
 	riscv_timebase = riscv_timebase_frequency(n);
-	clocksource_register_hz(&riscv_clocksource, riscv_timebase);
+	error = clocksource_register_hz(&riscv_clocksource, riscv_timebase);
 
+	if (error) {
+		pr_err("RISCV timer register failed [%d] for cpu = [%d]\n",
+		       error, cpuid);
+		return error;
+	}
 	error = cpuhp_setup_state(CPUHP_AP_RISCV_TIMER_STARTING,
 			 "clockevents/riscv/timer:starting",
 			 riscv_timer_starting_cpu, riscv_timer_dying_cpu);
 	if (error)
-		pr_err("RISCV timer register failed [%d] for cpu = [%d]\n",
-		       error, cpuid);
+		pr_err("cpu hp setup state failed for RISCV timer [%d]\n",
+		       error);
 	return error;
 }
 
-- 
2.7.4