path: root/drivers/bus
diff options
authorMarc Zyngier <marc.zyngier@arm.com>2017-10-03 18:14:12 +0100
committerPawel Moll <pawel.moll@arm.com>2017-12-04 16:53:26 +0000
commitb18c2b9487d8e797fc0a757e57ac3645348c5fba (patch)
tree344803f926b3920f4c46f6f056009c1900b671cf /drivers/bus
parent0f9afd36bac9543bc087b77016311c3394bd77c2 (diff)
bus: arm-ccn: Fix use of smp_processor_id() in preemptible context
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> Acked-by: Mark Rutland <mark.rutland@arm.com> Cc: stable@vger.kernel.org # 4.2+ Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Diffstat (limited to 'drivers/bus')
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/bus/arm-ccn.c b/drivers/bus/arm-ccn.c
index bbc1a2ef9639..508a1a389b7e 100644
--- a/drivers/bus/arm-ccn.c
+++ b/drivers/bus/arm-ccn.c
@@ -1300,7 +1300,7 @@ 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) {
@@ -1317,10 +1317,12 @@ static int arm_ccn_pmu_init(struct arm_ccn *ccn)
+ put_cpu();
return 0;
+ put_cpu();
ida_simple_remove(&arm_ccn_pmu_ida, ccn->dt.id);
for (i = 0; i < ccn->num_xps; i++)

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