commit 603a1621caa097be23c7784e36cb8edf23cd31db
author Arnd Bergmann <arnd@arndb.de> Mon Sep 27 14:16:35 2021 +0200
committer Kalle Valo <kvalo@codeaurora.org> Tue Sep 28 17:42:26 2021 +0300
tree 02d1b573ff16df691cfd77aa3ed746b957eefca7
parent 151a7c12c4fc8340b51e849e4d1fcb7d794777a5

mwifiex: avoid null-pointer-subtraction warning

clang complains about some NULL pointer arithmetic in this driver:

drivers/net/wireless/marvell/mwifiex/sta_tx.c:65:59: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
        pad = ((void *)skb->data - (sizeof(*local_tx_pd) + hroom)-
                                                                 ^
drivers/net/wireless/marvell/mwifiex/uap_txrx.c:478:53: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
        pad = ((void *)skb->data - (sizeof(*txpd) + hroom) - NULL) &

Rework that expression to do the same thing using a uintptr_t.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210927121656.940304-1-arnd@kernel.org

drivers/net/wireless/marvell/mwifiex/sta_tx.c

diff --git a/drivers/net/wireless/marvell/mwifiex/sta_tx.c b/drivers/net/wireless/marvell/mwifiex/sta_tx.c
index 2413053..a9b5eb9 100644
--- a/drivers/net/wireless/marvell/mwifiex/sta_tx.c
+++ b/drivers/net/wireless/marvell/mwifiex/sta_tx.c
@@ -62,8 +62,8 @@
 
 	pkt_type = mwifiex_is_skb_mgmt_frame(skb) ? PKT_TYPE_MGMT : 0;
 
-	pad = ((void *)skb->data - (sizeof(*local_tx_pd) + hroom)-
-			 NULL) & (MWIFIEX_DMA_ALIGN_SZ - 1);
+	pad = ((uintptr_t)skb->data - (sizeof(*local_tx_pd) + hroom)) &
+	       (MWIFIEX_DMA_ALIGN_SZ - 1);
 	skb_push(skb, sizeof(*local_tx_pd) + pad);
 
 	local_tx_pd = (struct txpd *) skb->data;

drivers/net/wireless/marvell/mwifiex/uap_txrx.c

diff --git a/drivers/net/wireless/marvell/mwifiex/uap_txrx.c b/drivers/net/wireless/marvell/mwifiex/uap_txrx.c
index 9bbdb8d..245ff64 100644
--- a/drivers/net/wireless/marvell/mwifiex/uap_txrx.c
+++ b/drivers/net/wireless/marvell/mwifiex/uap_txrx.c
@@ -475,8 +475,8 @@
 
 	pkt_type = mwifiex_is_skb_mgmt_frame(skb) ? PKT_TYPE_MGMT : 0;
 
-	pad = ((void *)skb->data - (sizeof(*txpd) + hroom) - NULL) &
-			(MWIFIEX_DMA_ALIGN_SZ - 1);
+	pad = ((uintptr_t)skb->data - (sizeof(*txpd) + hroom)) &
+	       (MWIFIEX_DMA_ALIGN_SZ - 1);
 
 	skb_push(skb, sizeof(*txpd) + pad);