USB: mutexification of usblp

this patch:
- converts usblp fully to mutex
- makes sleeping interruptible where EINTR can be returned anyway

Signed-off-by: Oliver Neukum <oliver@neukum.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 29 insertions, 25 deletions

diff --git a/drivers/usb/class/usblp.c b/drivers/usb/class/usblp.c
index 6303970e93c1..24ee8be359f5 100644
--- a/drivers/usb/class/usblp.c
+++ b/drivers/usb/class/usblp.c
@@ -130,7 +130,7 @@ MFG:HEWLETT-PACKARD;MDL:DESKJET 970C;CMD:MLC,PCL,PML;CLASS:PRINTER;DESCRIPTION:H
 
 struct usblp {
         struct usb_device       *dev;                   /* USB device */
-        struct semaphore        sem;                    /* locks this struct, especially "dev" */
+        struct mutex            mut;                    /* locks this struct, especially "dev" */
         char                    *writebuf;              /* write transfer_buffer */
         char                    *readbuf;               /* read transfer_buffer */
         char                    *statusbuf;             /* status transfer_buffer */
@@ -465,7 +465,7 @@ static long usblp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
         int twoints[2];
         int retval = 0;
 
-        down (&usblp->sem);
+        mutex_lock (&usblp->mut);
         if (!usblp->present) {
                 retval = -ENODEV;
                 goto done;
@@ -644,14 +644,14 @@ static long usblp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                 }
 
 done:
-        up (&usblp->sem);
+        mutex_unlock (&usblp->mut);
         return retval;
 }
 
 static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 {
         struct usblp *usblp = file->private_data;
-        int timeout, rv, err = 0, transfer_length = 0;
+        int timeout, intr, rv, err = 0, transfer_length = 0;
         size_t writecount = 0;
 
         while (writecount < count) {
@@ -668,14 +668,16 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
                         if (rv < 0)
                                 return writecount ? writecount : -EINTR;
                 }
-                down (&usblp->sem);
+                intr = mutex_lock_interruptible (&usblp->mut);
+                if (intr)
+                        return writecount ? writecount : -EINTR;
                 if (!usblp->present) {
-                        up (&usblp->sem);
+                        mutex_unlock (&usblp->mut);
                         return -ENODEV;
                 }
 
                 if (usblp->sleeping) {
-                        up (&usblp->sem);
+                        mutex_unlock (&usblp->mut);
                         return writecount ? writecount : -ENODEV;
                 }
 
@@ -687,10 +689,10 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
                                 err = usblp->writeurb->status;
                         } else
                                 err = usblp_check_status(usblp, err);
-                        up (&usblp->sem);
+                        mutex_unlock (&usblp->mut);
 
                         /* if the fault was due to disconnect, let khubd's
-                         * call to usblp_disconnect() grab usblp->sem ...
+                         * call to usblp_disconnect() grab usblp->mut ...
                          */
                         schedule ();
                         continue;
@@ -702,7 +704,7 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
                  */
                 writecount += transfer_length;
                 if (writecount == count) {
-                        up(&usblp->sem);
+                        mutex_unlock(&usblp->mut);
                         break;
                 }
 
@@ -714,7 +716,7 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
 
                 if (copy_from_user(usblp->writeurb->transfer_buffer, 
                                    buffer + writecount, transfer_length)) {
-                        up(&usblp->sem);
+                        mutex_unlock(&usblp->mut);
                         return writecount ? writecount : -EFAULT;
                 }
 
@@ -727,10 +729,10 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
                                 count = -EIO;
                         else
                                 count = writecount ? writecount : -ENOMEM;
-                        up (&usblp->sem);
+                        mutex_unlock (&usblp->mut);
                         break;
                 }
-                up (&usblp->sem);
+                mutex_unlock (&usblp->mut);
         }
 
         return count;
@@ -739,12 +741,14 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
 static ssize_t usblp_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 {
         struct usblp *usblp = file->private_data;
-        int rv;
+        int rv, intr;
 
         if (!usblp->bidir)
                 return -EINVAL;
 
-        down (&usblp->sem);
+        intr = mutex_lock_interruptible (&usblp->mut);
+        if (intr)
+                return -EINTR;
         if (!usblp->present) {
                 count = -ENODEV;
                 goto done;
@@ -757,9 +761,9 @@ static ssize_t usblp_read(struct file *file, char __user *buffer, size_t count,
                         count = -EAGAIN;
                         goto done;
                 }
-                up(&usblp->sem);
+                mutex_unlock(&usblp->mut);
                 rv = wait_event_interruptible(usblp->wait, usblp->rcomplete || !usblp->present);
-                down(&usblp->sem);
+                mutex_lock(&usblp->mut);
                 if (rv < 0) {
                         count = -EINTR;
                         goto done;
@@ -807,7 +811,7 @@ static ssize_t usblp_read(struct file *file, char __user *buffer, size_t count,
         }
 
 done:
-        up (&usblp->sem);
+        mutex_unlock (&usblp->mut);
         return count;
 }
 
@@ -886,7 +890,7 @@ static int usblp_probe(struct usb_interface *intf,
                 goto abort;
         }
         usblp->dev = dev;
-        init_MUTEX (&usblp->sem);
+        mutex_init (&usblp->mut);
         init_waitqueue_head(&usblp->wait);
         usblp->ifnum = intf->cur_altsetting->desc.bInterfaceNumber;
         usblp->intf = intf;
@@ -1178,7 +1182,7 @@ static void usblp_disconnect(struct usb_interface *intf)
         device_remove_file(&intf->dev, &dev_attr_ieee1284_id);
 
         mutex_lock (&usblp_mutex);
-        down (&usblp->sem);
+        mutex_lock (&usblp->mut);
         usblp->present = 0;
         usb_set_intfdata (intf, NULL);
 
@@ -1187,7 +1191,7 @@ static void usblp_disconnect(struct usb_interface *intf)
                         usblp->writebuf, usblp->writeurb->transfer_dma);
         usb_buffer_free (usblp->dev, USBLP_BUF_SIZE,
                         usblp->readbuf, usblp->readurb->transfer_dma);
-        up (&usblp->sem);
+        mutex_unlock (&usblp->mut);
 
         if (!usblp->used)
                 usblp_cleanup (usblp);
@@ -1200,11 +1204,11 @@ static int usblp_suspend (struct usb_interface *intf, pm_message_t message)
 
         /* this races against normal access and open */
         mutex_lock (&usblp_mutex);
-        down (&usblp->sem);
+        mutex_lock (&usblp->mut);
         /* we take no more IO */
         usblp->sleeping = 1;
         usblp_unlink_urbs(usblp);
-        up (&usblp->sem);
+        mutex_unlock (&usblp->mut);
         mutex_unlock (&usblp_mutex);
 
         return 0;
@@ -1216,12 +1220,12 @@ static int usblp_resume (struct usb_interface *intf)
         int r;
 
         mutex_lock (&usblp_mutex);
-        down (&usblp->sem);
+        mutex_lock (&usblp->mut);
 
         usblp->sleeping = 0;
         r = handle_bidir (usblp);
 
-        up (&usblp->sem);
+        mutex_unlock (&usblp->mut);
         mutex_unlock (&usblp_mutex);
 
         return r;