Merge tag 'regmap-debugfs-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap

Pull regmap debugfs optimisation fixes from Mark Brown:
 "The debugfs optimisations merged in v3.8 weren't my finest hour, there
  were a number of cases that the more complex algorithm made worse
  especially around the error handling.  This patch series should
  address those issues."

* tag 'regmap-debugfs-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap:
  regmap: debugfs: Make sure we store the last entry in the offset cache
  regmap: debugfs: Ensure a correct return value for empty caches
  regmap: debugfs: Discard the cache if we fail to allocate an entry
  regmap: debugfs: Fix check for block start in cached seeks
  regmap: debugfs: Fix attempts to read nonexistant register blocks

1 files changed, 40 insertions, 13 deletions

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index 07aad786f81..46a213a596e 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -56,6 +56,19 @@ static const struct file_operations regmap_name_fops = {
         .llseek = default_llseek,
 };
 
+static void regmap_debugfs_free_dump_cache(struct regmap *map)
+{
+        struct regmap_debugfs_off_cache *c;
+
+        while (!list_empty(&map->debugfs_off_cache)) {
+                c = list_first_entry(&map->debugfs_off_cache,
+                                     struct regmap_debugfs_off_cache,
+                                     list);
+                list_del(&c->list);
+                kfree(c);
+        }
+}
+
 /*
  * Work out where the start offset maps into register numbers, bearing
  * in mind that we suppress hidden registers.
@@ -91,8 +104,10 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
                         /* No cache entry?  Start a new one */
                         if (!c) {
                                 c = kzalloc(sizeof(*c), GFP_KERNEL);
-                                if (!c)
-                                        break;
+                                if (!c) {
+                                        regmap_debugfs_free_dump_cache(map);
+                                        return base;
+                                }
                                 c->min = p;
                                 c->base_reg = i;
                         }
@@ -101,14 +116,34 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
                 }
         }
 
+        /* Close the last entry off if we didn't scan beyond it */
+        if (c) {
+                c->max = p - 1;
+                list_add_tail(&c->list,
+                              &map->debugfs_off_cache);
+        } else {
+                return base;
+        }
+
+        /*
+         * This should never happen; we return above if we fail to
+         * allocate and we should never be in this code if there are
+         * no registers at all.
+         */
+        if (list_empty(&map->debugfs_off_cache)) {
+                WARN_ON(list_empty(&map->debugfs_off_cache));
+                return base;
+        }
+
         /* Find the relevant block */
         list_for_each_entry(c, &map->debugfs_off_cache, list) {
-                if (*pos >= c->min && *pos <= c->max) {
+                if (from >= c->min && from <= c->max) {
                         *pos = c->min;
                         return c->base_reg;
                 }
 
-                ret = c->max;
+                *pos = c->min;
+                ret = c->base_reg;
         }
 
         return ret;
@@ -387,16 +422,8 @@ void regmap_debugfs_init(struct regmap *map, const char *name)
 
 void regmap_debugfs_exit(struct regmap *map)
 {
-        struct regmap_debugfs_off_cache *c;
-
         debugfs_remove_recursive(map->debugfs);
-        while (!list_empty(&map->debugfs_off_cache)) {
-                c = list_first_entry(&map->debugfs_off_cache,
-                                     struct regmap_debugfs_off_cache,
-                                     list);
-                list_del(&c->list);
-                kfree(c);
-        }
+        regmap_debugfs_free_dump_cache(map);
         kfree(map->debugfs_name);
 }