xhci: split allocate interrupter into separate alloacte and add parts

The current function that both allocates and adds the interrupter isn't
optimal when using several interrupters. The array of interrupters need
to be protected with a lock while adding or removing interrupters.
If memory is allocated under the default xhci spinlock then GFP_KERNEL
can't be used.

There is no need to allocate the interrupter memory under the lock, so
split this code into separate unlocked allocate part, and a lock
protected add part.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Message-ID: <20230602144009.1225632-6-mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: matnyman

drivers/usb/host/xhci-mem.c

@@ -1831,13 +1831,15 @@ xhci_free_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
 	 * low or high 32 bits of ERSTBA immediately causes the controller to
 	 * dereference the partially cleared 64 bit address, causing IOMMU error.
 	 */
-	tmp = readl(&ir->ir_set->erst_size);
-	tmp &= ERST_SIZE_MASK;
-	writel(tmp, &ir->ir_set->erst_size);
-
-	tmp64 = xhci_read_64(xhci, &ir->ir_set->erst_dequeue);
-	tmp64 &= (u64) ERST_PTR_MASK;
-	xhci_write_64(xhci, tmp64, &ir->ir_set->erst_dequeue);
+	if (ir->ir_set) {
+		tmp = readl(&ir->ir_set->erst_size);
+		tmp &= ERST_SIZE_MASK;
+		writel(tmp, &ir->ir_set->erst_size);
+
+		tmp64 = xhci_read_64(xhci, &ir->ir_set->erst_dequeue);
+		tmp64 &= (u64) ERST_PTR_MASK;
+		xhci_write_64(xhci, tmp64, &ir->ir_set->erst_dequeue);
+	}
 
 	/* free interrrupter event ring */
 	if (ir->event_ring)
@@ -2227,43 +2229,50 @@ static int xhci_setup_port_arrays(struct xhci_hcd *xhci, gfp_t flags)
 }
 
 static struct xhci_interrupter *
-xhci_alloc_interrupter(struct xhci_hcd *xhci, unsigned int intr_num, gfp_t flags)
+xhci_alloc_interrupter(struct xhci_hcd *xhci, gfp_t flags)
 {
 	struct device *dev = xhci_to_hcd(xhci)->self.sysdev;
 	struct xhci_interrupter *ir;
-	u64 erst_base;
-	u32 erst_size;
 	int ret;
 
-	if (intr_num > xhci->max_interrupters) {
-		xhci_warn(xhci, "Can't allocate interrupter %d, max interrupters %d\n",
-			  intr_num, xhci->max_interrupters);
-		return NULL;
-	}
-
-	if (xhci->interrupter) {
-		xhci_warn(xhci, "Can't allocate already set up interrupter %d\n", intr_num);
-		return NULL;
-	}
-
 	ir = kzalloc_node(sizeof(*ir), flags, dev_to_node(dev));
 	if (!ir)
 		return NULL;
 
-	ir->ir_set = &xhci->run_regs->ir_set[intr_num];
 	ir->event_ring = xhci_ring_alloc(xhci, ERST_NUM_SEGS, 1, TYPE_EVENT,
 					0, flags);
 	if (!ir->event_ring) {
-		xhci_warn(xhci, "Failed to allocate interrupter %d event ring\n", intr_num);
-		goto fail_ir;
+		xhci_warn(xhci, "Failed to allocate interrupter event ring\n");
+		kfree(ir);
+		return NULL;
 	}
 
 	ret = xhci_alloc_erst(xhci, ir->event_ring, &ir->erst, flags);
 	if (ret) {
-		xhci_warn(xhci, "Failed to allocate interrupter %d erst\n", intr_num);
-		goto fail_ev;
+		xhci_warn(xhci, "Failed to allocate interrupter erst\n");
+		xhci_ring_free(xhci, ir->event_ring);
+		kfree(ir);
+		return NULL;
+	}
+
+	return ir;
+}
+
+static int
+xhci_add_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir,
+		     unsigned int intr_num)
+{
+	u64 erst_base;
+	u32 erst_size;
 
+	if (intr_num > xhci->max_interrupters) {
+		xhci_warn(xhci, "Can't add interrupter %d, max interrupters %d\n",
+			  intr_num, xhci->max_interrupters);
+		return -EINVAL;
 	}
+
+	ir->ir_set = &xhci->run_regs->ir_set[intr_num];
+
 	/* set ERST count with the number of entries in the segment table */
 	erst_size = readl(&ir->ir_set->erst_size);
 	erst_size &= ERST_SIZE_MASK;
@@ -2278,14 +2287,7 @@ xhci_alloc_interrupter(struct xhci_hcd *xhci, unsigned int intr_num, gfp_t flags
 	/* Set the event ring dequeue address of this interrupter */
 	xhci_set_hc_event_deq(xhci, ir);
 
-	return ir;
-
-fail_ev:
-	xhci_ring_free(xhci, ir->event_ring);
-fail_ir:
-	kfree(ir);
-
-	return NULL;
+	return 0;
 }
 
 int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
@@ -2407,15 +2409,17 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 		       "// Doorbell array is located at offset 0x%x from cap regs base addr",
 		       val);
 	xhci->dba = (void __iomem *) xhci->cap_regs + val;
-	/* Set ir_set to interrupt register set 0 */
 
-	/* allocate and set up primary interrupter with an event ring. */
+	/* Allocate and set up primary interrupter 0 with an event ring. */
 	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
 		       "Allocating primary event ring");
-	xhci->interrupter = xhci_alloc_interrupter(xhci, 0, flags);
+	xhci->interrupter = xhci_alloc_interrupter(xhci, flags);
 	if (!xhci->interrupter)
 		goto fail;
 
+	if (xhci_add_interrupter(xhci, xhci->interrupter, 0))
+		goto fail;
+
 	xhci->isoc_bei_interval = AVOID_BEI_INTERVAL_MAX;
 
 	/*