ieee1394: raw1394: narrow down the state_mutex protected region

Refactor the ioctl dispatcher in order to move a fraction of it out of
the section which is serialized by fi->state_mutex.  This is not so much
about performance but more about self-documentation:  The mutex_lock()/
mutex_unlock() calls are now closer to the data accesses which the mutex
protects, i.e. to the iso_state switch.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/ieee1394/raw1394.c

@@ -2556,52 +2556,46 @@ static int raw1394_mmap(struct file *file, struct vm_area_struct *vma)
 	return ret;
 }
 
-/* ioctl is only used for rawiso operations */
-static long do_raw1394_ioctl(struct file *file, unsigned int cmd,
-							unsigned long arg)
+static long raw1394_ioctl_inactive(struct file_info *fi, unsigned int cmd,
+				   void __user *argp)
 {
-	struct file_info *fi = file->private_data;
-	void __user *argp = (void __user *)arg;
-
-	switch (fi->iso_state) {
-	case RAW1394_ISO_INACTIVE:
 	switch (cmd) {
 	case RAW1394_IOC_ISO_XMIT_INIT:
 		return raw1394_iso_xmit_init(fi, argp);
 	case RAW1394_IOC_ISO_RECV_INIT:
 		return raw1394_iso_recv_init(fi, argp);
 	default:
-			break;
+		return -EINVAL;
 	}
-		break;
-	case RAW1394_ISO_RECV:
+}
+
+static long raw1394_ioctl_recv(struct file_info *fi, unsigned int cmd,
+			       unsigned long arg)
+{
+	void __user *argp = (void __user *)arg;
+
 	switch (cmd) {
 	case RAW1394_IOC_ISO_RECV_START:{
-				/* copy args from user-space */
 			int args[3];
-				if (copy_from_user
-				    (&args[0], argp, sizeof(args)))
+
+			if (copy_from_user(&args[0], argp, sizeof(args)))
 				return -EFAULT;
 			return hpsb_iso_recv_start(fi->iso_handle,
-							   args[0], args[1],
-							   args[2]);
+						   args[0], args[1], args[2]);
 		}
 	case RAW1394_IOC_ISO_XMIT_RECV_STOP:
 		hpsb_iso_stop(fi->iso_handle);
 		return 0;
 	case RAW1394_IOC_ISO_RECV_LISTEN_CHANNEL:
-			return hpsb_iso_recv_listen_channel(fi->iso_handle,
-							    arg);
+		return hpsb_iso_recv_listen_channel(fi->iso_handle, arg);
 	case RAW1394_IOC_ISO_RECV_UNLISTEN_CHANNEL:
-			return hpsb_iso_recv_unlisten_channel(fi->iso_handle,
-							      arg);
+		return hpsb_iso_recv_unlisten_channel(fi->iso_handle, arg);
 	case RAW1394_IOC_ISO_RECV_SET_CHANNEL_MASK:{
-				/* copy the u64 from user-space */
 			u64 mask;
+
 			if (copy_from_user(&mask, argp, sizeof(mask)))
 				return -EFAULT;
-				return hpsb_iso_recv_set_channel_mask(fi->
-								      iso_handle,
+			return hpsb_iso_recv_set_channel_mask(fi->iso_handle,
 							      mask);
 		}
 	case RAW1394_IOC_ISO_GET_STATUS:
@@ -2609,8 +2603,7 @@ static long do_raw1394_ioctl(struct file *file, unsigned int cmd,
 	case RAW1394_IOC_ISO_RECV_PACKETS:
 		return raw1394_iso_recv_packets(fi, argp);
 	case RAW1394_IOC_ISO_RECV_RELEASE_PACKETS:
-			return hpsb_iso_recv_release_packets(fi->iso_handle,
-							     arg);
+		return hpsb_iso_recv_release_packets(fi->iso_handle, arg);
 	case RAW1394_IOC_ISO_RECV_FLUSH:
 		return hpsb_iso_recv_flush(fi->iso_handle);
 	case RAW1394_IOC_ISO_SHUTDOWN:
@@ -2619,15 +2612,19 @@ static long do_raw1394_ioctl(struct file *file, unsigned int cmd,
 	case RAW1394_IOC_ISO_QUEUE_ACTIVITY:
 		queue_rawiso_event(fi);
 		return 0;
+	default:
+		return -EINVAL;
 	}
-		break;
-	case RAW1394_ISO_XMIT:
+}
+
+static long raw1394_ioctl_xmit(struct file_info *fi, unsigned int cmd,
+			       void __user *argp)
+{
 	switch (cmd) {
 	case RAW1394_IOC_ISO_XMIT_START:{
-				/* copy two ints from user-space */
 			int args[2];
-				if (copy_from_user
-				    (&args[0], argp, sizeof(args)))
+
+			if (copy_from_user(&args[0], argp, sizeof(args)))
 				return -EFAULT;
 			return hpsb_iso_xmit_start(fi->iso_handle,
 						   args[0], args[1]);
@@ -2647,11 +2644,18 @@ static long do_raw1394_ioctl(struct file *file, unsigned int cmd,
 	case RAW1394_IOC_ISO_QUEUE_ACTIVITY:
 		queue_rawiso_event(fi);
 		return 0;
-		}
-		break;
 	default:
-		break;
+		return -EINVAL;
 	}
+}
+
+/* ioctl is only used for rawiso operations */
+static long raw1394_ioctl(struct file *file, unsigned int cmd,
+			  unsigned long arg)
+{
+	struct file_info *fi = file->private_data;
+	void __user *argp = (void __user *)arg;
+	long ret;
 
 	/* state-independent commands */
 	switch(cmd) {
@@ -2661,18 +2665,25 @@ static long do_raw1394_ioctl(struct file *file, unsigned int cmd,
 		break;
 	}
 
-	return -EINVAL;
-}
+	mutex_lock(&fi->state_mutex);
 
-static long raw1394_ioctl(struct file *file, unsigned int cmd,
-							unsigned long arg)
-{
-	struct file_info *fi = file->private_data;
-	long ret;
+	switch (fi->iso_state) {
+	case RAW1394_ISO_INACTIVE:
+		ret = raw1394_ioctl_inactive(fi, cmd, argp);
+		break;
+	case RAW1394_ISO_RECV:
+		ret = raw1394_ioctl_recv(fi, cmd, arg);
+		break;
+	case RAW1394_ISO_XMIT:
+		ret = raw1394_ioctl_xmit(fi, cmd, argp);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
 
-	mutex_lock(&fi->state_mutex);
-	ret = do_raw1394_ioctl(file, cmd, arg);
 	mutex_unlock(&fi->state_mutex);
+
 	return ret;
 }
 
@@ -2710,7 +2721,7 @@ static long raw1394_iso_xmit_recv_packets32(struct file *file, unsigned int cmd,
 	    !copy_from_user(&infos32, &arg->infos, sizeof infos32)) {
 		infos = compat_ptr(infos32);
 		if (!copy_to_user(&dst->infos, &infos, sizeof infos))
-			err = do_raw1394_ioctl(file, cmd, (unsigned long)dst);
+			err = raw1394_ioctl(file, cmd, (unsigned long)dst);
 	}
 	return err;
 }
@@ -2734,7 +2745,6 @@ static long raw1394_compat_ioctl(struct file *file,
 	void __user *argp = (void __user *)arg;
 	long err;
 
-	mutex_lock(&fi->state_mutex);
 	switch (cmd) {
 	/* These requests have same format as long as 'int' has same size. */
 	case RAW1394_IOC_ISO_RECV_INIT:
@@ -2751,7 +2761,7 @@ static long raw1394_compat_ioctl(struct file *file,
 	case RAW1394_IOC_ISO_GET_STATUS:
 	case RAW1394_IOC_ISO_SHUTDOWN:
 	case RAW1394_IOC_ISO_QUEUE_ACTIVITY:
-		err = do_raw1394_ioctl(file, cmd, arg);
+		err = raw1394_ioctl(file, cmd, arg);
 		break;
 	/* These request have different format. */
 	case RAW1394_IOC_ISO_RECV_PACKETS32:
@@ -2767,7 +2777,6 @@ static long raw1394_compat_ioctl(struct file *file,
 		err = -EINVAL;
 		break;
 	}
-	mutex_unlock(&fi->state_mutex);
 
 	return err;
 }