usb: xhci: check if 'requested segments' exceeds ERST capacity

Check if requested segments ('segs' or 'ERST_DEFAULT_SEGS') exceeds the
maximum amount ERST supports.

When 'segs' is '0', 'ERST_DEFAULT_SEGS' is used instead. But both values
may not exceed ERST max.

Macro 'ERST_MAX_SEGS' is renamed to 'ERST_DEFAULT_SEGS'. The new name
better represents the macros, which is the number of Event Ring segments
to allocate, when the amount is not specified.

Additionally, rename and change xhci_create_secondary_interrupter()'s
argument 'int num_segs' to 'unsigned int segs'. This makes it the same
as its counter part in xhci_alloc_interrupter().

Fixes: c99b38c4 ("xhci: add support to allocate several interrupters")
Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20240429140245.3955523-4-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-mem.c

@@ -2259,24 +2259,24 @@ static int xhci_setup_port_arrays(struct xhci_hcd *xhci, gfp_t flags)
 }
 
 static struct xhci_interrupter *
-xhci_alloc_interrupter(struct xhci_hcd *xhci, int segs, gfp_t flags)
+xhci_alloc_interrupter(struct xhci_hcd *xhci, unsigned int segs, gfp_t flags)
 {
 	struct device *dev = xhci_to_hcd(xhci)->self.sysdev;
 	struct xhci_interrupter *ir;
-	unsigned int num_segs = segs;
+	unsigned int max_segs;
 	int ret;
 
+	if (!segs)
+		segs = ERST_DEFAULT_SEGS;
+
+	max_segs = BIT(HCS_ERST_MAX(xhci->hcs_params2));
+	segs = min(segs, max_segs);
+
 	ir = kzalloc_node(sizeof(*ir), flags, dev_to_node(dev));
 	if (!ir)
 		return NULL;
 
-	/* number of ring segments should be greater than 0 */
-	if (segs <= 0)
-		num_segs = min_t(unsigned int, 1 << HCS_ERST_MAX(xhci->hcs_params2),
-			 ERST_MAX_SEGS);
-
-	ir->event_ring = xhci_ring_alloc(xhci, num_segs, 1, TYPE_EVENT, 0,
-					 flags);
+	ir->event_ring = xhci_ring_alloc(xhci, segs, 1, TYPE_EVENT, 0, flags);
 	if (!ir->event_ring) {
 		xhci_warn(xhci, "Failed to allocate interrupter event ring\n");
 		kfree(ir);
@@ -2334,7 +2334,7 @@ xhci_add_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir,
 }
 
 struct xhci_interrupter *
-xhci_create_secondary_interrupter(struct usb_hcd *hcd, int num_seg)
+xhci_create_secondary_interrupter(struct usb_hcd *hcd, unsigned int segs)
 {
 	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
 	struct xhci_interrupter *ir;
@@ -2344,7 +2344,7 @@ xhci_create_secondary_interrupter(struct usb_hcd *hcd, int num_seg)
 	if (!xhci->interrupters || xhci->max_interrupters <= 1)
 		return NULL;
 
-	ir = xhci_alloc_interrupter(xhci, num_seg, GFP_KERNEL);
+	ir = xhci_alloc_interrupter(xhci, segs, GFP_KERNEL);
 	if (!ir)
 		return NULL;
 

drivers/usb/host/xhci.h

@@ -1392,8 +1392,8 @@ struct urb_priv {
 	struct	xhci_td	td[] __counted_by(num_tds);
 };
 
-/* Reasonable limit for number of Event Ring segments (spec allows 32k) */
-#define	ERST_MAX_SEGS	2
+/* Number of Event Ring segments to allocate, when amount is not specified. (spec allows 32k) */
+#define	ERST_DEFAULT_SEGS	2
 /* Poll every 60 seconds */
 #define	POLL_TIMEOUT	60
 /* Stop endpoint command timeout (secs) for URB cancellation watchdog timer */
@@ -1831,7 +1831,7 @@ struct xhci_container_ctx *xhci_alloc_container_ctx(struct xhci_hcd *xhci,
 void xhci_free_container_ctx(struct xhci_hcd *xhci,
 		struct xhci_container_ctx *ctx);
 struct xhci_interrupter *
-xhci_create_secondary_interrupter(struct usb_hcd *hcd, int num_seg);
+xhci_create_secondary_interrupter(struct usb_hcd *hcd, unsigned int segs);
 void xhci_remove_secondary_interrupter(struct usb_hcd
 				       *hcd, struct xhci_interrupter *ir);