powerpc/vas: Fix IRQ name allocation

The VAS device allocates a generic interrupt to handle page faults but
the IRQ name doesn't show under /proc. This is because it's on
stack. Allocate the name.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Haren Myneni <haren@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201212142707.2102141-1-clg@kaod.org

arch/powerpc/platforms/powernv/vas.c

@@ -28,12 +28,10 @@ static DEFINE_PER_CPU(int, cpu_vas_id);
 
 static int vas_irq_fault_window_setup(struct vas_instance *vinst)
 {
-	char devname[64];
 	int rc = 0;
 
-	snprintf(devname, sizeof(devname), "vas-%d", vinst->vas_id);
 	rc = request_threaded_irq(vinst->virq, vas_fault_handler,
-				vas_fault_thread_fn, 0, devname, vinst);
+				vas_fault_thread_fn, 0, vinst->name, vinst);
 
 	if (rc) {
 		pr_err("VAS[%d]: Request IRQ(%d) failed with %d\n",
@@ -80,6 +78,12 @@ static int init_vas_instance(struct platform_device *pdev)
 	if (!vinst)
 		return -ENOMEM;
 
+	vinst->name = kasprintf(GFP_KERNEL, "vas-%d", vasid);
+	if (!vinst->name) {
+		kfree(vinst);
+		return -ENOMEM;
+	}
+
 	INIT_LIST_HEAD(&vinst->node);
 	ida_init(&vinst->ida);
 	mutex_init(&vinst->mutex);
@@ -162,6 +166,7 @@ static int init_vas_instance(struct platform_device *pdev)
 	return 0;
 
 free_vinst:
+	kfree(vinst->name);
 	kfree(vinst);
 	return -ENODEV;
 

arch/powerpc/platforms/powernv/vas.h

@@ -340,6 +340,7 @@ struct vas_instance {
 	struct vas_window *rxwin[VAS_COP_TYPE_MAX];
 	struct vas_window *windows[VAS_WINDOWS_PER_CHIP];
 
+	char *name;
 	char *dbgname;
 	struct dentry *dbgdir;
 };