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Date:   Wed, 3 Apr 2019 11:46:11 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Arend van Spriel <arend.vanspriel@...adcom.com>,
        Franky Lin <franky.lin@...adcom.com>,
        Hante Meuleman <hante.meuleman@...adcom.com>,
        Chi-Hsien Lin <chi-hsien.lin@...ress.com>,
        Wright Feng <wright.feng@...ress.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>
Cc:     linux-wireless@...r.kernel.org,
        brcm80211-dev-list.pdl@...adcom.com,
        brcm80211-dev-list@...ress.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH][next] brcmfmac: 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 reqsz is not necessary,
hence it is removed.

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
---
 drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
index 8209a42dea72..07b3ba949da5 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
@@ -711,7 +711,6 @@ brcmf_fw_alloc_request(u32 chip, u32 chiprev,
 	size_t mp_path_len;
 	u32 i, j;
 	char end = '\0';
-	size_t reqsz;
 
 	for (i = 0; i < table_size; i++) {
 		if (mapping_table[i].chipid == chip &&
@@ -726,8 +725,7 @@ brcmf_fw_alloc_request(u32 chip, u32 chiprev,
 		return NULL;
 	}
 
-	reqsz = sizeof(*fwreq) + n_fwnames * sizeof(struct brcmf_fw_item);
-	fwreq = kzalloc(reqsz, GFP_KERNEL);
+	fwreq = kzalloc(struct_size(fwreq, items, n_fwnames), GFP_KERNEL);
 	if (!fwreq)
 		return NULL;
 
-- 
2.21.0

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