regmap: Ensure regmap_register_patch() is compatible with fast_io

With fast_io we use mutexes to lock the I/O operations so we would need
to do GFP_ATOMIC allocations if we wanted to do allocations inside the
lock as we do currently. Since it is unlikely that we will want to register
a patch outside of init where concurrency shouldn't be an issue move the
allocation of the patch data outside the lock.

Reported-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@linaro.org>

1 files changed, 14 insertions, 11 deletions

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 6a19515f8a45..e5a5509160fe 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -2173,6 +2173,9 @@ EXPORT_SYMBOL_GPL(regmap_async_complete);
  * apply them immediately.  Typically this is used to apply
  * corrections to be applied to the device defaults on startup, such
  * as the updates some vendors provide to undocumented registers.
+ *
+ * The caller must ensure that this function cannot be called
+ * concurrently with either itself or regcache_sync().
  */
 int regmap_register_patch(struct regmap *map, const struct reg_default *regs,
                           int num_regs)
@@ -2185,6 +2188,17 @@ int regmap_register_patch(struct regmap *map, const struct reg_default *regs,
             num_regs))
                 return 0;
 
+        p = krealloc(map->patch,
+                     sizeof(struct reg_default) * (map->patch_regs + num_regs),
+                     GFP_KERNEL);
+        if (p) {
+                memcpy(p + map->patch_regs, regs, num_regs * sizeof(*regs));
+                map->patch = p;
+                map->patch_regs += num_regs;
+        } else {
+                return -ENOMEM;
+        }
+
         map->lock(map->lock_arg);
 
         bypass = map->cache_bypass;
@@ -2202,17 +2216,6 @@ int regmap_register_patch(struct regmap *map, const struct reg_default *regs,
                 }
         }
 
-        p = krealloc(map->patch,
-                     sizeof(struct reg_default) * (map->patch_regs + num_regs),
-                     GFP_KERNEL);
-        if (p) {
-                memcpy(p + map->patch_regs, regs, num_regs * sizeof(*regs));
-                map->patch = p;
-                map->patch_regs += num_regs;
-        } else {
-                ret = -ENOMEM;
-        }
-
 out:
         map->async = false;
         map->cache_bypass = bypass;