mdm6600: Fix spinlock usage to avoid GFP_ATOMIC allocations

usb_serial holds an autopm reference before calling open, so the
modem is always resumed when open is called.

Change-Id: Ica2f4e69620fd1d80f4bfc43dd3453313c1be185
Signed-off-by: Benoit Goby <benoit@android.com>

diff --git a/drivers/usb/serial/mdm6600.c b/drivers/usb/serial/mdm6600.c
index 8df23d928d20a9a64519997b1fa5ea0b18df89cb..112ac616dbb376b07e6448a610e88d0374c5d109 100644 (file)
--- a/drivers/usb/serial/mdm6600.c
+++ b/drivers/usb/serial/mdm6600.c
@@ -71,6 +71,7 @@ struct mdm6600_urb_write_pool {
        struct usb_anchor delayed;
        int buffer_sz;  /* allocated urb buffer size */
        int pending; /* number of in flight or delayed writes */
+       spinlock_t pending_lock;
 };
 
 struct mdm6600_urb_read_pool {
@@ -220,6 +221,7 @@ static int mdm6600_attach(struct usb_serial *serial)
        }
 
        spin_lock_init(&modem->susp_lock);
+       spin_lock_init(&modem->write.pending_lock);
 
        snprintf(modem->readlock_name, sizeof(modem->readlock_name),
                                        "mdm6600_read.%d", modem->number);
@@ -312,7 +314,7 @@ static int mdm6600_submit_urbs(struct mdm6600_port *modem)
 
        if (modem->number == MODEM_INTERFACE_NUM) {
                WARN_ON_ONCE(!modem->port->interrupt_in_urb);
-               rc = usb_submit_urb(modem->port->interrupt_in_urb, GFP_ATOMIC);
+               rc = usb_submit_urb(modem->port->interrupt_in_urb, GFP_KERNEL);
                if (rc) {
                        pr_err("%s: failed to submit interrupt urb, error %d\n",
                            __func__, rc);
@@ -321,7 +323,7 @@ static int mdm6600_submit_urbs(struct mdm6600_port *modem)
        }
        for (i = 0; i < POOL_SZ; i++) {
                usb_anchor_urb(modem->read.urb[i], &modem->read.in_flight);
-               rc = usb_submit_urb(modem->read.urb[i], GFP_ATOMIC);
+               rc = usb_submit_urb(modem->read.urb[i], GFP_KERNEL);
                if (rc) {
                        usb_unanchor_urb(modem->read.urb[i]);
                        pr_err("%s: failed to submit bulk read urb, error %d\n",
@@ -338,7 +340,6 @@ static int mdm6600_open(struct tty_struct *tty, struct usb_serial_port *port)
 {
        struct mdm6600_port *modem = usb_get_serial_data(port->serial);
        int status;
-       unsigned long flags;
 
        dbg("%s: port %d", __func__, modem->number);
 
@@ -346,15 +347,8 @@ static int mdm6600_open(struct tty_struct *tty, struct usb_serial_port *port)
 
        modem->tiocm_status = 0;
 
-       spin_lock_irqsave(&modem->susp_lock, flags);
        modem->opened = 1;
-       if (modem->susp_count) {
-               spin_unlock_irqrestore(&modem->susp_lock, flags);
-               usb_autopm_put_interface(modem->serial->interface);
-               return 0;
-       }
        status = mdm6600_submit_urbs(modem);
-       spin_unlock_irqrestore(&modem->susp_lock, flags);
 
        usb_autopm_put_interface(modem->serial->interface);
        return status;
@@ -445,12 +439,12 @@ static void mdm6600_write_bulk_cb(struct urb *u)
        if (mdm6600_mark_write_urb_unused(&modem->write, u))
                pr_warn("%s unknown urb %p\n", __func__, u);
 
-       spin_lock_irqsave(&modem->susp_lock, flags);
+       spin_lock_irqsave(&modem->write.pending_lock, flags);
        if (--modem->write.pending == 0) {
                usb_autopm_put_interface_async(modem->serial->interface);
                wake_unlock(&modem->writelock);
        }
-       spin_unlock_irqrestore(&modem->susp_lock, flags);
+       spin_unlock_irqrestore(&modem->write.pending_lock, flags);
 }
 
 static int mdm6600_write(struct tty_struct *tty, struct usb_serial_port *port,
@@ -480,30 +474,34 @@ static int mdm6600_write(struct tty_struct *tty, struct usb_serial_port *port,
        usb_serial_debug_data(debug_data, &port->dev, __func__,
                u->transfer_buffer_length, u->transfer_buffer);
 
-       spin_lock_irqsave(&modem->susp_lock, flags);
+       spin_lock_irqsave(&modem->write.pending_lock, flags);
        if (modem->write.pending++ == 0) {
                wake_lock(&modem->writelock);
                usb_autopm_get_interface_async(modem->serial->interface);
        }
+       spin_unlock_irqrestore(&modem->write.pending_lock, flags);
 
+       spin_lock_irqsave(&modem->susp_lock, flags);
        if (modem->susp_count) {
                usb_anchor_urb(u, &modem->write.delayed);
-       } else {
-               usb_anchor_urb(u, &modem->write.in_flight);
-               rc = usb_submit_urb(u, GFP_ATOMIC);
-               if (rc < 0) {
-                       pr_err("%s: submit bulk urb failed %d\n", __func__, rc);
-                       usb_unanchor_urb(u);
-                       if (--modem->write.pending == 0) {
-                               usb_autopm_put_interface_async(serial->interface);
-                               wake_unlock(&modem->writelock);
-                       }
-                       spin_unlock_irqrestore(&modem->susp_lock, flags);
-                       return rc;
-               }
+               spin_unlock_irqrestore(&modem->susp_lock, flags);
+               return count;
        }
        spin_unlock_irqrestore(&modem->susp_lock, flags);
 
+       usb_anchor_urb(u, &modem->write.in_flight);
+       rc = usb_submit_urb(u, GFP_KERNEL);
+       if (rc < 0) {
+               pr_err("%s: submit bulk urb failed %d\n", __func__, rc);
+               usb_unanchor_urb(u);
+               spin_lock_irqsave(&modem->write.pending_lock, flags);
+               if (--modem->write.pending == 0) {
+                       usb_autopm_put_interface_async(serial->interface);
+                       wake_unlock(&modem->writelock);
+               }
+               spin_unlock_irqrestore(&modem->write.pending_lock, flags);
+               return rc;
+       }
        return count;
 }