qtnfmac: 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;
    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 code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

diff --git a/drivers/net/wireless/quantenna/qtnfmac/commands.c b/drivers/net/wireless/quantenna/qtnfmac/commands.c
index 659e7649fe22fa7bc2fb2310e020124051561cd0..cf386f579060d7673feedc68737c55b90d29ba00 100644 (file)
--- a/drivers/net/wireless/quantenna/qtnfmac/commands.c
+++ b/drivers/net/wireless/quantenna/qtnfmac/commands.c
@@ -914,9 +914,8 @@ qtnf_cmd_resp_proc_hw_info(struct qtnf_bus *bus,
        if (WARN_ON(resp->n_reg_rules > NL80211_MAX_SUPP_REG_RULES))
                return -E2BIG;
 
-       hwinfo->rd = kzalloc(sizeof(*hwinfo->rd)
-                            + sizeof(struct ieee80211_reg_rule)
-                            * resp->n_reg_rules, GFP_KERNEL);
+       hwinfo->rd = kzalloc(struct_size(hwinfo->rd, reg_rules,
+                                        resp->n_reg_rules), GFP_KERNEL);
 
        if (!hwinfo->rd)
                return -ENOMEM;