linux-kernel - [PATCH v2] regmap: Allocate buffers with GFP_ATOMIC when fast

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Date:	Fri, 11 Sep 2015 16:37:05 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Mark Brown <broonie@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Abhijeet Dharmapurikar <adharmap@...eaurora.org>
Subject: [PATCH v2] 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@...eaurora.org>
Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
---

Changes since v1:
 * Only modify allocations in regmap_bulk_write() path

 drivers/base/regmap/internal.h |  1 +
 drivers/base/regmap/regmap.c   | 12 +++++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 873ddf91c9d3..3470ec146f12 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 29128c6af445..dc90f2ac332a 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -563,6 +563,16 @@ 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);
@@ -1729,7 +1739,7 @@ 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;
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

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