Re: [PATCH] rtlwifi: rtl8192cu: remove pointless memcpy
From: Larry Finger <hidden>
Date: 2018-02-09 16:44:23
Also in:
linux-wireless, lkml
On 02/09/2018 07:24 AM, Arnd Bergmann wrote:
quoted hunk ↗ jump to hunk
gcc-8 points out that source and destination of the memcpy() are always the same pointer, so the effect of memcpy() is undefined here (its arguments must not overlap): drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c: In function '_rtl_rx_process': drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c:430:2: error: 'memcpy' source argument is the same as destination [-Werror=restrict] Most likely this is harmless, but it's easy to just remove the line and get rid of the warning. Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c | 1 - 1 file changed, 1 deletion(-)diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c b/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c index ac4a82de40c7..9ab56827124e 100644 --- a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c +++ b/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c@@ -427,7 +427,6 @@ static void _rtl_rx_process(struct ieee80211_hw *hw, struct sk_buff *skb) (u32)hdr->addr1[0], (u32)hdr->addr1[1], (u32)hdr->addr1[2], (u32)hdr->addr1[3], (u32)hdr->addr1[4], (u32)hdr->addr1[5]); - memcpy(IEEE80211_SKB_RXCB(skb), rx_status, sizeof(*rx_status)); ieee80211_rx(hw, skb); }
No, the warning is pointing to the wrong place. The routine in question does the following: 1. Loads the rx_status struct from skb->cb. 2. Overwrites the contents with 0. 3. Fills various members of the struct. 4. Writes the revised struct back into skb->cb. Thus eliminating step 4 negates all the things done in step 3, and is wrong. The correct fix is to change step 1 to create a NULL-filled rx_status struct, and eliminate step 2. NACK. Larry