[PATCH 2/4] libertas: debugfs: use kzalloc() to allocate formatting buffers

[Mike Rapoport (Microsoft)]

libertas debugfs functions allocate buffers for formatting debug
output text using get_zeroed_page().

These buffers can be allocated with kmalloc() as there's nothing special
about them to go directly to the page allocator.

kmalloc() provides a better API that does not require ugly casts and
kfree() does not need to know the size of the freed object.

Performance difference between kmalloc() and __get_free_pages() is not
measurable as both allocators take an object/page from a per-CPU list for
fast path allocations.

For the slow path the performance is anyway determined by the amount of
reclaim involved rather than by what allocator is used.

Replace use of get_zeroed_page() with kzalloc() and free_page() with
kfree().

Link: https://lore.kernel.org/all/635405e4-9423-4a25-a6e7-e03c8ea0bcbe@redhat.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt at kernel.org>
---
 drivers/net/wireless/marvell/libertas/debugfs.c | 39 ++++++++++---------------
 1 file changed, 16 insertions(+), 23 deletions(-)

diff --git a/drivers/net/wireless/marvell/libertas/debugfs.c b/drivers/net/wireless/marvell/libertas/debugfs.c
index 9ebd69134940..9428f954837a 100644
--- a/drivers/net/wireless/marvell/libertas/debugfs.c
+++ b/drivers/net/wireless/marvell/libertas/debugfs.c
@@ -35,8 +35,7 @@ static ssize_t lbs_dev_info(struct file *file, char __user *userbuf,
 {
 	struct lbs_private *priv = file->private_data;
 	size_t pos = 0;
-	unsigned long addr = get_zeroed_page(GFP_KERNEL);
-	char *buf = (char *)addr;
+	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 	ssize_t res;
 	if (!buf)
 		return -ENOMEM;
@@ -48,7 +47,7 @@ static ssize_t lbs_dev_info(struct file *file, char __user *userbuf,
 
 	res = simple_read_from_buffer(userbuf, count, ppos, buf, pos);
 
-	free_page(addr);
+	kfree(buf);
 	return res;
 }
 
@@ -96,8 +95,7 @@ static ssize_t lbs_sleepparams_read(struct file *file, char __user *userbuf,
 	ssize_t ret;
 	size_t pos = 0;
 	struct sleep_params sp;
-	unsigned long addr = get_zeroed_page(GFP_KERNEL);
-	char *buf = (char *)addr;
+	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
@@ -113,7 +111,7 @@ static ssize_t lbs_sleepparams_read(struct file *file, char __user *userbuf,
 	ret = simple_read_from_buffer(userbuf, count, ppos, buf, pos);
 
 out_unlock:
-	free_page(addr);
+	kfree(buf);
 	return ret;
 }
 
@@ -165,8 +163,7 @@ static ssize_t lbs_host_sleep_read(struct file *file, char __user *userbuf,
 	struct lbs_private *priv = file->private_data;
 	ssize_t ret;
 	size_t pos = 0;
-	unsigned long addr = get_zeroed_page(GFP_KERNEL);
-	char *buf = (char *)addr;
+	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
@@ -174,7 +171,7 @@ static ssize_t lbs_host_sleep_read(struct file *file, char __user *userbuf,
 
 	ret = simple_read_from_buffer(userbuf, count, ppos, buf, pos);
 
-	free_page(addr);
+	kfree(buf);
 	return ret;
 }
 
@@ -228,7 +225,7 @@ static ssize_t lbs_threshold_read(uint16_t tlv_type, uint16_t event_mask,
 	u8 freq;
 	int events = 0;
 
-	buf = (char *)get_zeroed_page(GFP_KERNEL);
+	buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
@@ -261,7 +258,7 @@ static ssize_t lbs_threshold_read(uint16_t tlv_type, uint16_t event_mask,
 	kfree(subscribed);
 
  out_page:
-	free_page((unsigned long)buf);
+	kfree(buf);
 	return ret;
 }
 
@@ -436,8 +433,7 @@ static ssize_t lbs_rdmac_read(struct file *file, char __user *userbuf,
 	struct lbs_private *priv = file->private_data;
 	ssize_t pos = 0;
 	int ret;
-	unsigned long addr = get_zeroed_page(GFP_KERNEL);
-	char *buf = (char *)addr;
+	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 	u32 val = 0;
 
 	if (!buf)
@@ -450,7 +446,7 @@ static ssize_t lbs_rdmac_read(struct file *file, char __user *userbuf,
 				priv->mac_offset, val);
 		ret = simple_read_from_buffer(userbuf, count, ppos, buf, pos);
 	}
-	free_page(addr);
+	kfree(buf);
 	return ret;
 }
 
@@ -506,8 +502,7 @@ static ssize_t lbs_rdbbp_read(struct file *file, char __user *userbuf,
 	struct lbs_private *priv = file->private_data;
 	ssize_t pos = 0;
 	int ret;
-	unsigned long addr = get_zeroed_page(GFP_KERNEL);
-	char *buf = (char *)addr;
+	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 	u32 val;
 
 	if (!buf)
@@ -520,7 +515,7 @@ static ssize_t lbs_rdbbp_read(struct file *file, char __user *userbuf,
 				priv->bbp_offset, val);
 		ret = simple_read_from_buffer(userbuf, count, ppos, buf, pos);
 	}
-	free_page(addr);
+	kfree(buf);
 
 	return ret;
 }
@@ -578,8 +573,7 @@ static ssize_t lbs_rdrf_read(struct file *file, char __user *userbuf,
 	struct lbs_private *priv = file->private_data;
 	ssize_t pos = 0;
 	int ret;
-	unsigned long addr = get_zeroed_page(GFP_KERNEL);
-	char *buf = (char *)addr;
+	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 	u32 val;
 
 	if (!buf)
@@ -592,7 +586,7 @@ static ssize_t lbs_rdrf_read(struct file *file, char __user *userbuf,
 				priv->rf_offset, val);
 		ret = simple_read_from_buffer(userbuf, count, ppos, buf, pos);
 	}
-	free_page(addr);
+	kfree(buf);
 
 	return ret;
 }
@@ -812,8 +806,7 @@ static ssize_t lbs_debugfs_read(struct file *file, char __user *userbuf,
 	char *p;
 	int i;
 	struct debug_data *d;
-	unsigned long addr = get_zeroed_page(GFP_KERNEL);
-	char *buf = (char *)addr;
+	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
@@ -836,7 +829,7 @@ static ssize_t lbs_debugfs_read(struct file *file, char __user *userbuf,
 
 	res = simple_read_from_buffer(userbuf, count, ppos, p, pos);
 
-	free_page(addr);
+	kfree(buf);
 	return res;
 }
 

-- 
2.53.0