From: Matthew Wilcox <willy@infradead.org>
Date: Mon, 18 Feb 2019 22:47:01 +0000 (-0500)
Subject: uio: Convert uio_idr to XArray
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=0f9443a4320a7d53c2550515d4e42028b1f9970f;p=users%2Fwilly%2Fxarray.git

uio: Convert uio_idr to XArray

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index a57698985f9c..5e9a43fc3aed 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -18,23 +18,20 @@
 #include <linux/device.h>
 #include <linux/slab.h>
 #include <linux/mm.h>
-#include <linux/idr.h>
 #include <linux/sched/signal.h>
 #include <linux/string.h>
 #include <linux/kobject.h>
 #include <linux/cdev.h>
 #include <linux/uio_driver.h>
+#include <linux/xarray.h>
 
 #define UIO_MAX_DEVICES		(1U << MINORBITS)
 
 static int uio_major;
 static struct cdev *uio_cdev;
-static DEFINE_IDR(uio_idr);
+static DEFINE_XARRAY_ALLOC(uio_devs);
 static const struct file_operations uio_fops;
 
-/* Protect idr accesses */
-static DEFINE_MUTEX(minor_lock);
-
 /*
  * attributes
  */
@@ -398,26 +395,21 @@ static void uio_dev_del_attributes(struct uio_device *idev)
 
 static int uio_get_minor(struct uio_device *idev)
 {
-	int retval = -ENOMEM;
-
-	mutex_lock(&minor_lock);
-	retval = idr_alloc(&uio_idr, idev, 0, UIO_MAX_DEVICES, GFP_KERNEL);
-	if (retval >= 0) {
-		idev->minor = retval;
-		retval = 0;
-	} else if (retval == -ENOSPC) {
+	int err;
+
+	err = xa_alloc(&uio_devs, &idev->minor, idev,
+			XA_LIMIT(0, UIO_MAX_DEVICES - 1), GFP_KERNEL);
+	if (err == -EBUSY) {
 		dev_err(&idev->dev, "too many uio devices\n");
-		retval = -EINVAL;
+		err = -EINVAL;
 	}
-	mutex_unlock(&minor_lock);
-	return retval;
+
+	return err;
 }
 
 static void uio_free_minor(struct uio_device *idev)
 {
-	mutex_lock(&minor_lock);
-	idr_remove(&uio_idr, idev->minor);
-	mutex_unlock(&minor_lock);
+	xa_erase(&uio_devs, idev->minor);
 }
 
 /**
@@ -462,9 +454,7 @@ static int uio_open(struct inode *inode, struct file *filep)
 	struct uio_listener *listener;
 	int ret = 0;
 
-	mutex_lock(&minor_lock);
-	idev = idr_find(&uio_idr, iminor(inode));
-	mutex_unlock(&minor_lock);
+	idev = xa_load(&uio_devs, iminor(inode));
 	if (!idev) {
 		ret = -ENODEV;
 		goto out;
@@ -1038,7 +1028,6 @@ static int __init uio_init(void)
 static void __exit uio_exit(void)
 {
 	release_uio_class();
-	idr_destroy(&uio_idr);
 }
 
 module_init(uio_init)