pmu/smmuv3: Clear IRQ affinity hint on device removal

Currently when trying to remove the SMMUv3 PMU module we get a
WARN_ON_ONCE from free_irq(), because the affinity hint set during probe
hasn't been properly cleared.

[  238.878383] WARNING: CPU: 0 PID: 175 at kernel/irq/manage.c:1744 free_irq+0x324/0x358
...
[  238.897263] Call trace:
[  238.897998]  free_irq+0x324/0x358
[  238.898792]  devm_irq_release+0x18/0x28
[  238.899189]  release_nodes+0x1b0/0x228
[  238.899984]  devres_release_all+0x38/0x60
[  238.900779]  device_release_driver_internal+0x10c/0x1d0
[  238.901574]  driver_detach+0x50/0xe0
[  238.902368]  bus_remove_driver+0x5c/0xd8
[  238.903448]  driver_unregister+0x30/0x60
[  238.903958]  platform_driver_unregister+0x14/0x20
[  238.905075]  arm_smmu_pmu_exit+0x1c/0xecc [arm_smmuv3_pmu]
[  238.905547]  __arm64_sys_delete_module+0x14c/0x260
[  238.906342]  el0_svc_common.constprop.0+0x74/0x178
[  238.907355]  do_el0_svc+0x24/0x90
[  238.907932]  el0_sync_handler+0x11c/0x198
[  238.908979]  el0_sync+0x158/0x180

Just like the other perf drivers, clear the affinity hint before
releasing the device.

Fixes: 7d839b4b ("perf/smmuv3: Add arm64 smmuv3 pmu driver")
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20200422084805.237738-1-jean-philippe@linaro.orgSigned-off-by: Will Deacon <will@kernel.org>

drivers/perf/arm_smmuv3_pmu.c

@@ -814,7 +814,7 @@ static int smmu_pmu_probe(struct platform_device *pdev)
 	if (err) {
 		dev_err(dev, "Error %d registering hotplug, PMU @%pa\n",
 			err, &res_0->start);
-		return err;
+		goto out_clear_affinity;
 	}
 
 	err = perf_pmu_register(&smmu_pmu->pmu, name, -1);
@@ -833,6 +833,8 @@ static int smmu_pmu_probe(struct platform_device *pdev)
 
 out_unregister:
 	cpuhp_state_remove_instance_nocalls(cpuhp_state_num, &smmu_pmu->node);
+out_clear_affinity:
+	irq_set_affinity_hint(smmu_pmu->irq, NULL);
 	return err;
 }
 
@@ -842,6 +844,7 @@ static int smmu_pmu_remove(struct platform_device *pdev)
 
 	perf_pmu_unregister(&smmu_pmu->pmu);
 	cpuhp_state_remove_instance_nocalls(cpuhp_state_num, &smmu_pmu->node);
+	irq_set_affinity_hint(smmu_pmu->irq, NULL);
 
 	return 0;
 }