Re: [PATCH net-next v2 2/2] net: wwan: add exclusive open mode capability to AT and QCDM ports

Add exclusive open mode capability to AT and QCDM ports to improve
compatibility with user-space tools using the Qualcomm diagnostic
device (e.g. libqcdm).

Signed-off-by: Daniele Palmas <redacted>
---
 drivers/net/wwan/wwan_core.c | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index 8168239e52c3..8acb09dcb83a 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c

@@ -22,6 +22,7 @@
 #include <linux/termios.h>
 #include <linux/gnss.h>
 #include <linux/wwan.h>
+#include <linux/tty.h>
 #include <net/rtnetlink.h>
 #include <uapi/linux/wwan.h>

@@ -79,7 +80,7 @@ struct wwan_device {
  * @data_lock: Port specific data access serialization
  * @headroom_len: SKB reserved headroom size
  * @frag_len: Length to fragment packet
- * @at_data: AT port specific data
+ * @at_data: AT/QCDM port specific data
  * @gnss: Pointer to GNSS device associated with this port
  */
 struct wwan_port {

@@ -98,6 +99,7 @@ struct wwan_port {
                struct {
                        struct ktermios termios;
                        int mdmbits;
+                       unsigned long flags;
                } at_data;
                struct gnss_device *gnss;
        };

@@ -748,6 +750,14 @@ static int wwan_port_op_start(struct wwan_port *port)
                goto out_unlock;
        }

+       /* Check exclusive open mode for AT and QCDM ports */
+       if ((port->type == WWAN_PORT_AT || port->type == WWAN_PORT_QCDM) &&
+           test_bit(TTY_EXCLUSIVE, &port->at_data.flags) &&
+           !capable(CAP_SYS_ADMIN)) {
+               ret = -EBUSY;
+               goto out_unlock;
+       }

+
        /* If port is already started, don't start again */
        if (!port->start_count)
                ret = port->ops->start(port);

@@ -769,6 +779,8 @@ static void wwan_port_op_stop(struct wwan_port *port)
                if (port->ops)
                        port->ops->stop(port);
                skb_queue_purge(&port->rxq);
+               if (port->type == WWAN_PORT_AT || port->type == WWAN_PORT_QCDM)
+                       clear_bit(TTY_EXCLUSIVE, &port->at_data.flags);
        }
        mutex_unlock(&port->ops_lock);
 }

@@ -1031,6 +1043,22 @@ static long wwan_port_fops_at_ioctl(struct wwan_port *port, unsigned int cmd,
                break;
        }

+       case TIOCEXCL:
+               set_bit(TTY_EXCLUSIVE, &port->at_data.flags);
+               break;
+
+       case TIOCNXCL:
+               clear_bit(TTY_EXCLUSIVE, &port->at_data.flags);
+               break;
+
+       case TIOCGEXCL:
+       {
+               int excl = test_bit(TTY_EXCLUSIVE, &port->at_data.flags);
+
+               ret = put_user(excl, (int __user *)arg);
+               break;
+       }
+
        default:
                ret = -ENOIOCTLCMD;
        }
--

2.43.0