Subject: [PATCH] ath10k: use struct_size() in kzalloc()

From: "Gustavo A. R. Silva" <[email-masked]>
Date: Thu, 23 Aug 2018 20:12:47 -0500

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct foo {
	int stuff;
        void *entry[];
};

instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This issue was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <[email-masked]>
---
 drivers/net/wireless/ath/ath10k/ce.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/ce.c b/drivers/net/wireless/ath/ath10k/ce.c
index 18c709c..d0381aa 100644
--- a/drivers/net/wireless/ath/ath10k/ce.c
+++ b/drivers/net/wireless/ath/ath10k/ce.c
@@ -1416,10 +1416,8 @@ ath10k_ce_alloc_src_ring(struct ath10k *ar, unsigned int ce_id,
 
 	nentries = roundup_pow_of_two(nentries);
 
-	src_ring = kzalloc(sizeof(*src_ring) +
-			   (nentries *
-			    sizeof(*src_ring->per_transfer_context)),
-			   GFP_KERNEL);
+	src_ring = kzalloc(struct_size(src_ring, per_transfer_context,
+				       nentries), GFP_KERNEL);
 	if (src_ring == NULL)
 		return ERR_PTR(-ENOMEM);
 
@@ -1476,10 +1474,8 @@ ath10k_ce_alloc_src_ring_64(struct ath10k *ar, unsigned int ce_id,
 
 	nentries = roundup_pow_of_two(nentries);
 
-	src_ring = kzalloc(sizeof(*src_ring) +
-			   (nentries *
-			    sizeof(*src_ring->per_transfer_context)),
-			   GFP_KERNEL);
+	src_ring = kzalloc(struct_size(src_ring, per_transfer_context,
+				       nentries), GFP_KERNEL);
 	if (!src_ring)
 		return ERR_PTR(-ENOMEM);
 
@@ -1534,10 +1530,8 @@ ath10k_ce_alloc_dest_ring(struct ath10k *ar, unsigned int ce_id,
 
 	nentries = roundup_pow_of_two(attr->dest_nentries);
 
-	dest_ring = kzalloc(sizeof(*dest_ring) +
-			    (nentries *
-			     sizeof(*dest_ring->per_transfer_context)),
-			    GFP_KERNEL);
+	dest_ring = kzalloc(struct_size(dest_ring, per_transfer_context,
+					nentries), GFP_KERNEL);
 	if (dest_ring == NULL)
 		return ERR_PTR(-ENOMEM);
 
@@ -1580,10 +1574,8 @@ ath10k_ce_alloc_dest_ring_64(struct ath10k *ar, unsigned int ce_id,
 
 	nentries = roundup_pow_of_two(attr->dest_nentries);
 
-	dest_ring = kzalloc(sizeof(*dest_ring) +
-			    (nentries *
-			     sizeof(*dest_ring->per_transfer_context)),
-			    GFP_KERNEL);
+	dest_ring = kzalloc(struct_size(dest_ring, per_transfer_context,
+					nentries), GFP_KERNEL);
 	if (!dest_ring)
 		return ERR_PTR(-ENOMEM);
 
-- 
2.7.4