Merge tag 'char-misc-5.2-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

Pull char/misc update part 2 from Greg KH:
 "Here is the "real" big set of char/misc driver patches for 5.2-rc1

  Loads of different driver subsystem stuff in here, all over the places:
   - thunderbolt driver updates
   - habanalabs driver updates
   - nvmem driver updates
   - extcon driver updates
   - intel_th driver updates
   - mei driver updates
   - coresight driver updates
   - soundwire driver cleanups and updates
   - fastrpc driver updates
   - other minor driver updates
   - chardev minor fixups

  Feels like this tree is getting to be a dumping ground of "small
  driver subsystems" these days. Which is fine with me, if it makes
  things easier for those subsystem maintainers.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'char-misc-5.2-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (255 commits)
  intel_th: msu: Add current window tracking
  intel_th: msu: Add a sysfs attribute to trigger window switch
  intel_th: msu: Correct the block wrap detection
  intel_th: Add switch triggering support
  intel_th: gth: Factor out trace start/stop
  intel_th: msu: Factor out pipeline draining
  intel_th: msu: Switch over to scatterlist
  intel_th: msu: Replace open-coded list_{first,last,next}_entry variants
  intel_th: Only report useful IRQs to subdevices
  intel_th: msu: Start handling IRQs
  intel_th: pci: Use MSI interrupt signalling
  intel_th: Communicate IRQ via resource
  intel_th: Add "rtit" source device
  intel_th: Skip subdevices if their MMIO is missing
  intel_th: Rework resource passing between glue layers and core
  intel_th: SPDX-ify the documentation
  intel_th: msu: Fix single mode with IOMMU
  coresight: funnel: Support static funnel
  dt-bindings: arm: coresight: Unify funnel DT binding
  coresight: replicator: Add new device id for static replicator
  ...

1 files changed, 37 insertions, 41 deletions

diff --git a/fs/char_dev.c b/fs/char_dev.c
index a279c58fe360..d18cad28c1c3 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -88,22 +88,31 @@ static int find_dynamic_major(void)
 /*
  * Register a single major with a specified minor range.
  *
- * If major == 0 this functions will dynamically allocate a major and return
- * its number.
- *
- * If major > 0 this function will attempt to reserve the passed range of
- * minors and will return zero on success.
+ * If major == 0 this function will dynamically allocate an unused major.
+ * If major > 0 this function will attempt to reserve the range of minors
+ * with given major.
  *
- * Returns a -ve errno on failure.
  */
 static struct char_device_struct *
 __register_chrdev_region(unsigned int major, unsigned int baseminor,
 			   int minorct, const char *name)
 {
-	struct char_device_struct *cd, **cp;
-	int ret = 0;
+	struct char_device_struct *cd, *curr, *prev = NULL;
+	int ret = -EBUSY;
 	int i;
 
+	if (major >= CHRDEV_MAJOR_MAX) {
+		pr_err("CHRDEV \"%s\" major requested (%u) is greater than the maximum (%u)\n",
+		       name, major, CHRDEV_MAJOR_MAX-1);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (minorct > MINORMASK + 1 - baseminor) {
+		pr_err("CHRDEV \"%s\" minor range requested (%u-%u) is out of range of maximum range (%u-%u) for a single major\n",
+			name, baseminor, baseminor + minorct - 1, 0, MINORMASK);
+		return ERR_PTR(-EINVAL);
+	}
+
 	cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
 	if (cd == NULL)
 		return ERR_PTR(-ENOMEM);
@@ -120,10 +129,20 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
 		major = ret;
 	}
 
-	if (major >= CHRDEV_MAJOR_MAX) {
-		pr_err("CHRDEV \"%s\" major requested (%u) is greater than the maximum (%u)\n",
-		       name, major, CHRDEV_MAJOR_MAX-1);
-		ret = -EINVAL;
+	i = major_to_index(major);
+	for (curr = chrdevs[i]; curr; prev = curr, curr = curr->next) {
+		if (curr->major < major)
+			continue;
+
+		if (curr->major > major)
+			break;
+
+		if (curr->baseminor + curr->minorct <= baseminor)
+			continue;
+
+		if (curr->baseminor >= baseminor + minorct)
+			break;
+
 		goto out;
 	}
 
@@ -132,37 +151,14 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
 	cd->minorct = minorct;
 	strlcpy(cd->name, name, sizeof(cd->name));
 
-	i = major_to_index(major);
-
-	for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
-		if ((*cp)->major > major ||
-		    ((*cp)->major == major &&
-		     (((*cp)->baseminor >= baseminor) ||
-		      ((*cp)->baseminor + (*cp)->minorct > baseminor))))
-			break;
-
-	/* Check for overlapping minor ranges.  */
-	if (*cp && (*cp)->major == major) {
-		int old_min = (*cp)->baseminor;
-		int old_max = (*cp)->baseminor + (*cp)->minorct - 1;
-		int new_min = baseminor;
-		int new_max = baseminor + minorct - 1;
-
-		/* New driver overlaps from the left.  */
-		if (new_max >= old_min && new_max <= old_max) {
-			ret = -EBUSY;
-			goto out;
-		}
-
-		/* New driver overlaps from the right.  */
-		if (new_min <= old_max && new_min >= old_min) {
-			ret = -EBUSY;
-			goto out;
-		}
+	if (!prev) {
+		cd->next = curr;
+		chrdevs[i] = cd;
+	} else {
+		cd->next = prev->next;
+		prev->next = cd;
 	}
 
-	cd->next = *cp;
-	*cp = cd;
 	mutex_unlock(&chrdevs_lock);
 	return cd;
 out: