linux-kernel - [PATCH 1/3] usbip: Convert CONFIG_USBIP_VHCI_NR

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Message-ID: <20251104113248.223594-2-lec.jakub@gmail.com>
Date: Tue,  4 Nov 2025 12:32:46 +0100
From: Jakub Lecki <lec.jakub@...il.com>
To: linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Valentina Manea <valentina.manea.m@...il.com>,
	Shuah Khan <shuah@...nel.org>,
	Hongren Zheng <i@...ithal.me>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jakub Lecki <lec.jakub@...il.com>
Subject: [PATCH 1/3] usbip: Convert CONFIG_USBIP_VHCI_NR_HCS to a module parameter.

In workflows involving a greater number of remote
USB/IP devices, the default number of available virtual ports may be
insufficient, forcing user to recompile the module with greater number
of configured virtual host controllers and/or number of ports.

Allow a user to configure the number of USB/IP virtual host controllers
via a new 'num_controllers' module parameter to simplify the usage of
this module.

VHCI controller structures are already dynamically allocated during
module initialization, so the only change is switch from assigning
'vhci_num_controllers' via Kconfig to using the module parameter
framework.

- Remove the USBIP_VHCI_NR_HCS Kconfig option and replace it with a
  module parameter.
- Trim the value of the configured 'num_controllers' parameter if it
  exceeds bounds, and emit a warning.

Signed-off-by: Jakub Lecki <lec.jakub@...il.com>
---
 drivers/usb/usbip/Kconfig    | 11 -----------
 drivers/usb/usbip/vhci.h     |  9 +++------
 drivers/usb/usbip/vhci_hcd.c | 16 ++++++++++++++--
 3 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/drivers/usb/usbip/Kconfig b/drivers/usb/usbip/Kconfig
index b9f94e2e278d..bdcb6f4fdbec 100644
--- a/drivers/usb/usbip/Kconfig
+++ b/drivers/usb/usbip/Kconfig
@@ -38,17 +38,6 @@ config USBIP_VHCI_HC_PORTS
 	  host controller driver, this defines number of ports per
 	  USB/IP virtual host controller.
 
-config USBIP_VHCI_NR_HCS
-	int "Number of USB/IP virtual host controllers"
-	range 1 128
-	default 1
-	depends on USBIP_VHCI_HCD
-	help
-	  To increase number of ports available for USB/IP virtual
-	  host controller driver, this defines number of USB/IP
-	  virtual host controllers as if adding physical host
-	  controllers.
-
 config USBIP_HOST
 	tristate "Host driver"
 	depends on USBIP_CORE && USB
diff --git a/drivers/usb/usbip/vhci.h b/drivers/usb/usbip/vhci.h
index 5659dce1526e..30b8540e0b49 100644
--- a/drivers/usb/usbip/vhci.h
+++ b/drivers/usb/usbip/vhci.h
@@ -82,11 +82,8 @@ enum hub_speed {
 /* Each VHCI has 2 hubs (USB2 and USB3), each has VHCI_HC_PORTS ports */
 #define VHCI_PORTS	(VHCI_HC_PORTS*2)
 
-#ifdef CONFIG_USBIP_VHCI_NR_HCS
-#define VHCI_NR_HCS CONFIG_USBIP_VHCI_NR_HCS
-#else
-#define VHCI_NR_HCS 1
-#endif
+#define VHCI_DEFAULT_NR_HCS 1
+#define VHCI_MAX_NR_HCS 128
 
 #define MAX_STATUS_NAME 16
 
@@ -118,7 +115,7 @@ struct vhci_hcd {
 	struct vhci_device vdev[VHCI_HC_PORTS];
 };
 
-extern int vhci_num_controllers;
+extern unsigned int vhci_num_controllers;
 extern struct vhci *vhcis;
 extern struct attribute_group vhci_attr_group;
 
diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c
index e70fba9f55d6..93c3fa3e1c53 100644
--- a/drivers/usb/usbip/vhci_hcd.c
+++ b/drivers/usb/usbip/vhci_hcd.c
@@ -10,6 +10,7 @@
 #include <linux/kthread.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/printk.h>
 #include <linux/slab.h>
 #include <linux/string_choices.h>
 
@@ -44,7 +45,12 @@ static int vhci_get_frame_number(struct usb_hcd *hcd);
 static const char driver_name[] = "vhci_hcd";
 static const char driver_desc[] = "USB/IP Virtual Host Controller";
 
-int vhci_num_controllers = VHCI_NR_HCS;
+unsigned int vhci_num_controllers = VHCI_DEFAULT_NR_HCS;
+module_param_named(num_controllers, vhci_num_controllers, uint, 0444);
+MODULE_PARM_DESC(num_controllers, "Number of USB/IP virtual host controllers (range: 0-"
+		 __MODULE_STRING(VHCI_MAX_NR_HCS) ", default: "
+		 __MODULE_STRING(VHCI_DEFAULT_NR_HCS) ")");
+
 struct vhci *vhcis;
 
 static const char * const bit_desc[] = {
@@ -1510,8 +1516,14 @@ static int __init vhci_hcd_init(void)
 	if (usb_disabled())
 		return -ENODEV;
 
-	if (vhci_num_controllers < 1)
+	if (vhci_num_controllers < 1) {
+		pr_warn("num_controllers less than 1, setting to 1\n");
 		vhci_num_controllers = 1;
+	} else if (vhci_num_controllers > VHCI_MAX_NR_HCS) {
+		pr_warn("num_controllers too high, limiting to %d\n",
+			VHCI_MAX_NR_HCS);
+		vhci_num_controllers = VHCI_MAX_NR_HCS;
+	}
 
 	vhcis = kcalloc(vhci_num_controllers, sizeof(struct vhci), GFP_KERNEL);
 	if (vhcis == NULL)
-- 
2.43.0