From: Marc Zyngier <marc.zyngier@arm.com>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Pawel Moll <pawel.moll@arm.com>,
Mark Rutland <mark.rutland@arm.com>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH v2 1/2] bus: arm-ccn: Fix use of smp_processor_id() in preemptible context
Date: Tue, 3 Oct 2017 18:14:12 +0100 [thread overview]
Message-ID: <20171003171413.18592-2-marc.zyngier@arm.com> (raw)
In-Reply-To: <20171003171413.18592-1-marc.zyngier@arm.com>
Booting a DEBUG_PREEMPT enabled kernel on a CCN-based system
results in the following splat:
[...]
arm-ccn e8000000.ccn: No access to interrupts, using timer.
BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
caller is debug_smp_processor_id+0x1c/0x28
CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.13.0 #6111
Hardware name: AMD Seattle/Seattle, BIOS 17:08:23 Jun 26 2017
Call trace:
[<ffff000008089e78>] dump_backtrace+0x0/0x278
[<ffff00000808a22c>] show_stack+0x24/0x30
[<ffff000008bc3bc4>] dump_stack+0x8c/0xb0
[<ffff00000852b534>] check_preemption_disabled+0xfc/0x100
[<ffff00000852b554>] debug_smp_processor_id+0x1c/0x28
[<ffff000008551bd8>] arm_ccn_probe+0x358/0x4f0
[...]
as we use smp_processor_id() in the wrong context.
Turn this into a get_cpu()/put_cpu() that extends over the CPU hotplug
registration, making sure that we don't race against a CPU down operation.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
drivers/bus/arm-ccn.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/bus/arm-ccn.c b/drivers/bus/arm-ccn.c
index e8c6946fed9d..8614d7fa457e 100644
--- a/drivers/bus/arm-ccn.c
+++ b/drivers/bus/arm-ccn.c
@@ -1297,7 +1297,7 @@ static int arm_ccn_pmu_init(struct arm_ccn *ccn)
}
/* Pick one CPU which we will use to collect data from CCN... */
- cpumask_set_cpu(smp_processor_id(), &ccn->dt.cpu);
+ cpumask_set_cpu(get_cpu(), &ccn->dt.cpu);
/* Also make sure that the overflow interrupt is handled by this CPU */
if (ccn->irq) {
@@ -1314,10 +1314,12 @@ static int arm_ccn_pmu_init(struct arm_ccn *ccn)
cpuhp_state_add_instance_nocalls(CPUHP_AP_PERF_ARM_CCN_ONLINE,
&ccn->dt.node);
+ put_cpu();
return 0;
error_pmu_register:
error_set_affinity:
+ put_cpu();
ida_simple_remove(&arm_ccn_pmu_ida, ccn->dt.id);
for (i = 0; i < ccn->num_xps; i++)
writel(0, ccn->xp[i].base + CCN_XP_DT_CONTROL);
--
2.11.0
next prev parent reply other threads:[~2017-10-03 17:14 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-03 17:14 [PATCH v2 0/2] bus: CCN/CCI: Fix use of smp_processor_id() Marc Zyngier
2017-10-03 17:14 ` Marc Zyngier [this message]
2017-10-04 11:26 ` [PATCH v2 1/2] bus: arm-ccn: Fix use of smp_processor_id() in preemptible context Pawel Moll
2017-10-04 12:32 ` Marc Zyngier
2017-10-04 12:33 ` Pawel Moll
2017-10-03 17:14 ` [PATCH v2 2/2] bus: arm-cci: " Marc Zyngier
2017-10-03 17:18 ` [PATCH v2 0/2] bus: CCN/CCI: Fix use of smp_processor_id() Mark Rutland
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