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

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Date:	Thu, 10 Sep 2015 12:27:01 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Mark Brown <broonie@...nel.org>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] regmap: Allocate buffers with GFP_ATOMIC when fast_io == true

If a regmap is using fast_io, allocate buffers in the write APIs
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>
---
 drivers/base/regmap/internal.h |  1 +
 drivers/base/regmap/regmap.c   | 16 +++++++++++-----
 2 files changed, 12 insertions(+), 5 deletions(-)

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..0ad22f4d40b1 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -563,6 +563,12 @@ struct regmap *regmap_init(struct device *dev,
 		}
 		map->lock_arg = map;
 	}
+
+	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);
@@ -1296,7 +1302,7 @@ int _regmap_raw_write(struct regmap *map, unsigned int reg,
 				return -ENOMEM;
 
 			async->work_buf = kzalloc(map->format.buf_size,
-						  GFP_KERNEL | GFP_DMA);
+						  map->alloc_flags | GFP_DMA);
 			if (!async->work_buf) {
 				kfree(async);
 				return -ENOMEM;
@@ -1358,7 +1364,7 @@ int _regmap_raw_write(struct regmap *map, unsigned int reg,
 	/* If that didn't work fall back on linearising by hand. */
 	if (ret == -ENOTSUPP) {
 		len = map->format.reg_bytes + map->format.pad_bytes + val_len;
-		buf = kzalloc(len, GFP_KERNEL);
+		buf = kzalloc(len, map->alloc_flags);
 		if (!buf)
 			return -ENOMEM;
 
@@ -1729,7 +1735,7 @@ 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;
@@ -1771,7 +1777,7 @@ static int _regmap_raw_multi_reg_write(struct regmap *map,
 	if (!len)
 		return -EINVAL;
 
-	buf = kzalloc(len, GFP_KERNEL);
+	buf = kzalloc(len, map->alloc_flags);
 	if (!buf)
 		return -ENOMEM;
 
@@ -1909,7 +1915,7 @@ static int _regmap_multi_reg_write(struct regmap *map,
 		if (range) {
 			size_t len = sizeof(struct reg_sequence)*num_regs;
 			struct reg_sequence *base = kmemdup(regs, len,
-							   GFP_KERNEL);
+							   map->alloc_flags);
 			if (!base)
 				return -ENOMEM;
 			ret = _regmap_range_multi_paged_reg_write(map, base,
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

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