| Message ID | 20180209132531.2755482-1-arnd@arndb.de |
|---|---|
| State | Accepted |
| Commit | dcdd54c2bcae086a5834d3f823914d7535843b17 |
| Headers | show |
| Series | rtlwifi: rtl8192cu: remove pointless memcpy | expand |
On Fri, 2018-02-09 at 14:24 +0100, Arnd Bergmann wrote: > 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); > } trivia: The RT_TRACE above this should probably use %pM too. Not submitted as it would just cause a conflict. --- drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c b/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c index ac4a82de40c7..61da667ed8ba 100644 --- a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c +++ b/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c @@ -422,11 +422,8 @@ static void _rtl_rx_process(struct ieee80211_hw *hw, struct sk_buff *skb) if (ieee80211_is_data(fc)) RT_TRACE(rtlpriv, COMP_INIT, DBG_DMESG, "Got data frame\n"); RT_TRACE(rtlpriv, COMP_INIT, DBG_DMESG, - "Fram: fc = 0x%X addr1 = 0x%02X:0x%02X:0x%02X:0x%02X:0x%02X:0x%02X\n", - fc, - (u32)hdr->addr1[0], (u32)hdr->addr1[1], - (u32)hdr->addr1[2], (u32)hdr->addr1[3], - (u32)hdr->addr1[4], (u32)hdr->addr1[5]); + "Fram: fc = 0x%X addr1 = %pM\n", + fc, hdr->addr1); memcpy(IEEE80211_SKB_RXCB(skb), rx_status, sizeof(*rx_status)); ieee80211_rx(hw, skb); }
On 02/09/2018 07:24 AM, Arnd Bergmann wrote: > 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
On 02/09/2018 07:24 AM, Arnd Bergmann wrote: > 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); > } Argh. Once again I got tripped up on pointers. Yes, this patch is correct. Acked-by: Larry Finger <Larry.Finger@lwfinger.net> Sorry about the noise. Larry
Arnd Bergmann <arnd@arndb.de> wrote: > 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> > Acked-by: Larry Finger <Larry.Finger@lwfinger.net> Patch applied to wireless-drivers-next.git, thanks. dcdd54c2bcae rtlwifi: rtl8192cu: remove pointless memcpy -- https://patchwork.kernel.org/patch/10208979/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
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); }
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(-) -- 2.9.0