mwifiex: use struct_size() in kzalloc()

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;
    struct boo entry[];
};

size = sizeof(struct foo) + count * sizeof(struct boo); instance = kzalloc(size, 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)

Notice that, in this case, variable regd_size is not necessary, hence it is removed.

This code was detected with the help of Coccinelle.

---
 drivers/net/wireless/marvell/mwifiex/sta_cmdresp.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

index 69e3b624adbb..24b33e20e7a9 100644
@@ -1025,17 +1025,14 @@ mwifiex_create_custom_regdomain(struct mwifiex_private *priv,
 	struct ieee80211_regdomain *regd;
 	struct ieee80211_reg_rule *rule;
 	bool new_rule;
-	int regd_size, idx, freq, prev_freq = 0;
+	int idx, freq, prev_freq = 0;
 	u32 bw, prev_bw = 0;
 	u8 chflags, prev_chflags = 0, valid_rules = 0;
 
 	if (WARN_ON_ONCE(num_chan > NL80211_MAX_SUPP_REG_RULES))
 		return ERR_PTR(-EINVAL);
 
-	regd_size = sizeof(struct ieee80211_regdomain) +
-		    num_chan * sizeof(struct ieee80211_reg_rule);
-
-	regd = kzalloc(regd_size, GFP_KERNEL);
+	regd = kzalloc(struct_size(regd, reg_rules, num_chan), GFP_KERNEL);
 	if (!regd)
 		return ERR_PTR(-ENOMEM);
 

2.21.0

Patch applied to wireless-drivers-next.git, thanks.

ae187ba91541 mwifiex: use struct_size() in kzalloc()

https://patchwork.kernel.org/patch/10884249/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches