regmap: Allocate buffers with GFP_ATOMIC when fast_io == true

If a regmap is using fast_io, allocate the scratch buffer in
regmap_bulk_write() with GFP_ATOMIC instead of GFP_KERNEL.
Otherwise we may schedule while atomic.

Reported-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

2 files changed, 12 insertions, 1 deletions

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index cc557886ab23..f3b1445da0a5 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -59,6 +59,7 @@ struct regmap {
         regmap_lock lock;
         regmap_unlock unlock;
         void *lock_arg; /* This is passed to lock/unlock functions */
+        gfp_t alloc_flags;
 
         struct device *dev; /* Device we do I/O on */
         void *work_buf;     /* Scratch buffer used to format I/O */
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index afaf56200674..0b51190c13df 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -561,6 +561,16 @@ struct regmap *__regmap_init(struct device *dev,
                 }
                 map->lock_arg = map;
         }
+
+        /*
+         * When we write in fast-paths with regmap_bulk_write() don't allocate
+         * scratch buffers with sleeping allocations.
+         */
+        if ((bus && bus->fast_io) || config->fast_io)
+                map->alloc_flags = GFP_ATOMIC;
+        else
+                map->alloc_flags = GFP_KERNEL;
+
         map->format.reg_bytes = DIV_ROUND_UP(config->reg_bits, 8);
         map->format.pad_bytes = config->pad_bits / 8;
         map->format.val_bytes = DIV_ROUND_UP(config->val_bits, 8);
@@ -1786,7 +1796,7 @@ out:
                 if (!val_count)
                         return -EINVAL;
 
-                wval = kmemdup(val, val_count * val_bytes, GFP_KERNEL);
+                wval = kmemdup(val, val_count * val_bytes, map->alloc_flags);
                 if (!wval) {
                         dev_err(map->dev, "Error in memory allocation\n");
                         return -ENOMEM;