Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <89df78d0-fb52-9045-2074-1d6f0afae4d9@infradead.org>
Date:   Sat, 27 May 2023 16:08:03 -0700
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.11.0
From:   Randy Dunlap <rdunlap@infradead.org>
Subject: scsi/stex time_after() build warnings
To:     linux-scsi@vger.kernel.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Content-Language: en-US
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

Hi,

When I build stex.o for i386, I see these build warnings:

In file included from ../include/linux/bitops.h:7,
                 from ../include/linux/kernel.h:22,
                 from ../drivers/scsi/stex.c:13:
../drivers/scsi/stex.c: In function ‘stex_common_handshake’:
../include/linux/typecheck.h:12:25: warning: comparison of distinct pointer types lacks a cast
   12 |         (void)(&__dummy == &__dummy2); \
      |                         ^~
../include/linux/jiffies.h:106:10: note: in expansion of macro ‘typecheck’
  106 |          typecheck(unsigned long, b) && \
      |          ^~~~~~~~~
../drivers/scsi/stex.c:1035:29: note: in expansion of macro ‘time_after’
 1035 |                         if (time_after(jiffies, before + MU_MAX_DELAY * HZ)) {
      |                             ^~~~~~~~~~
../include/linux/typecheck.h:12:25: warning: comparison of distinct pointer types lacks a cast
   12 |         (void)(&__dummy == &__dummy2); \
      |                         ^~
../include/linux/jiffies.h:106:10: note: in expansion of macro ‘typecheck’
  106 |          typecheck(unsigned long, b) && \
      |          ^~~~~~~~~
../drivers/scsi/stex.c:1085:21: note: in expansion of macro ‘time_after’
 1085 |                 if (time_after(jiffies, before + MU_MAX_DELAY * HZ)) {
      |                     ^~~~~~~~~~
../drivers/scsi/stex.c: In function ‘stex_ss_handshake’:
../include/linux/typecheck.h:12:25: warning: comparison of distinct pointer types lacks a cast
   12 |         (void)(&__dummy == &__dummy2); \
      |                         ^~
../include/linux/jiffies.h:106:10: note: in expansion of macro ‘typecheck’
  106 |          typecheck(unsigned long, b) && \
      |          ^~~~~~~~~
../drivers/scsi/stex.c:1121:29: note: in expansion of macro ‘time_after’
 1121 |                         if (time_after(jiffies, before + MU_MAX_DELAY * HZ)) {
      |                             ^~~~~~~~~~
../include/linux/typecheck.h:12:25: warning: comparison of distinct pointer types lacks a cast
   12 |         (void)(&__dummy == &__dummy2); \
      |                         ^~
../include/linux/jiffies.h:106:10: note: in expansion of macro ‘typecheck’
  106 |          typecheck(unsigned long, b) && \
      |          ^~~~~~~~~
../drivers/scsi/stex.c:1133:29: note: in expansion of macro ‘time_after’
 1133 |                         if (time_after(jiffies, before + MU_MAX_DELAY * HZ)) {
      |                             ^~~~~~~~~~
../include/linux/typecheck.h:12:25: warning: comparison of distinct pointer types lacks a cast
   12 |         (void)(&__dummy == &__dummy2); \
      |                         ^~
../include/linux/jiffies.h:106:10: note: in expansion of macro ‘typecheck’
  106 |          typecheck(unsigned long, b) && \
      |          ^~~~~~~~~
../drivers/scsi/stex.c:1186:29: note: in expansion of macro ‘time_after’
 1186 |                         if (time_after(jiffies, before + MU_MAX_DELAY * HZ)) {
      |                             ^~~~~~~~~~
../include/linux/typecheck.h:12:25: warning: comparison of distinct pointer types lacks a cast
   12 |         (void)(&__dummy == &__dummy2); \
      |                         ^~
../include/linux/jiffies.h:106:10: note: in expansion of macro ‘typecheck’
  106 |          typecheck(unsigned long, b) && \
      |          ^~~~~~~~~
../drivers/scsi/stex.c:1199:29: note: in expansion of macro ‘time_after’
 1199 |                         if (time_after(jiffies, before + MU_MAX_DELAY * HZ)) {
      |                             ^~~~~~~~~~
../drivers/scsi/stex.c: In function ‘stex_yos_reset’:
../include/linux/typecheck.h:12:25: warning: comparison of distinct pointer types lacks a cast
   12 |         (void)(&__dummy == &__dummy2); \
      |                         ^~
../include/linux/jiffies.h:106:10: note: in expansion of macro ‘typecheck’
  106 |          typecheck(unsigned long, b) && \
      |          ^~~~~~~~~
../drivers/scsi/stex.c:1355:21: note: in expansion of macro ‘time_after’
 1355 |                 if (time_after(jiffies, before + ST_INTERNAL_TIMEOUT * HZ)) {
      |                     ^~~~~~~~~~
../drivers/scsi/stex.c: In function ‘stex_hba_stop’:
../include/linux/typecheck.h:12:25: warning: comparison of distinct pointer types lacks a cast
   12 |         (void)(&__dummy == &__dummy2); \
      |                         ^~
../include/linux/jiffies.h:106:10: note: in expansion of macro ‘typecheck’
  106 |          typecheck(unsigned long, b) && \
      |          ^~~~~~~~~
../drivers/scsi/stex.c:1902:21: note: in expansion of macro ‘time_after’
 1902 |                 if (time_after(jiffies, before + ST_INTERNAL_TIMEOUT * HZ)) {
      |                     ^~~~~~~~~~


but I don't see this type of warning for any other SCSI drivers
and I don't see this problem for stex.o on x86_64.

Does anyone have a clue about why this happens?


If I modify each timer_after() check to use a calculated unsigned long
variable, the warnings do not happen (as in the patch below).

Thanks.
-- 
~Randy
---
 drivers/scsi/stex.c |   32 ++++++++++++++++++++------------
 1 file changed, 20 insertions(+), 12 deletions(-)

diff -- a/drivers/scsi/stex.c b/drivers/scsi/stex.c
--- a/drivers/scsi/stex.c
+++ b/drivers/scsi/stex.c
@@ -1025,14 +1025,15 @@ static int stex_common_handshake(struct
 	struct handshake_frame *h;
 	dma_addr_t status_phys;
 	u32 data;
-	unsigned long before;
+	unsigned long before, timeout;
 
 	if (readl(base + OMR0) != MU_HANDSHAKE_SIGNATURE) {
 		writel(MU_INBOUND_DOORBELL_HANDSHAKE, base + IDBL);
 		readl(base + IDBL);
 		before = jiffies;
 		while (readl(base + OMR0) != MU_HANDSHAKE_SIGNATURE) {
-			if (time_after(jiffies, before + MU_MAX_DELAY * HZ)) {
+			timeout = before + MU_MAX_DELAY * HZ;
+			if (time_after(jiffies, timeout)) {
 				printk(KERN_ERR DRV_NAME
 					"(%s): no handshake signature\n",
 					pci_name(hba->pdev));
@@ -1082,7 +1083,8 @@ static int stex_common_handshake(struct
 	udelay(10);
 	before = jiffies;
 	while (readl(base + OMR0) != MU_HANDSHAKE_SIGNATURE) {
-		if (time_after(jiffies, before + MU_MAX_DELAY * HZ)) {
+		timeout = before + MU_MAX_DELAY * HZ;
+		if (time_after(jiffies, timeout)) {
 			printk(KERN_ERR DRV_NAME
 				"(%s): no signature after handshake frame\n",
 				pci_name(hba->pdev));
@@ -1110,7 +1112,7 @@ static int stex_ss_handshake(struct st_h
 	struct handshake_frame *h;
 	__le32 *scratch;
 	u32 data, scratch_size, mailboxdata, operationaldata;
-	unsigned long before;
+	unsigned long before, timeout;
 	int ret = 0;
 
 	before = jiffies;
@@ -1118,7 +1120,8 @@ static int stex_ss_handshake(struct st_h
 	if (hba->cardtype == st_yel) {
 		operationaldata = readl(base + YIOA_STATUS);
 		while (operationaldata != SS_MU_OPERATIONAL) {
-			if (time_after(jiffies, before + MU_MAX_DELAY * HZ)) {
+			timeout = before + MU_MAX_DELAY * HZ;
+			if (time_after(jiffies, timeout)) {
 				printk(KERN_ERR DRV_NAME
 					"(%s): firmware not operational\n",
 					pci_name(hba->pdev));
@@ -1130,7 +1133,8 @@ static int stex_ss_handshake(struct st_h
 	} else {
 		operationaldata = readl(base + PSCRATCH3);
 		while (operationaldata != SS_MU_OPERATIONAL) {
-			if (time_after(jiffies, before + MU_MAX_DELAY * HZ)) {
+			timeout = before + MU_MAX_DELAY * HZ;
+			if (time_after(jiffies, timeout)) {
 				printk(KERN_ERR DRV_NAME
 					"(%s): firmware not operational\n",
 					pci_name(hba->pdev));
@@ -1183,7 +1187,8 @@ static int stex_ss_handshake(struct st_h
 	scratch = hba->scratch;
 	if (hba->cardtype == st_yel) {
 		while (!(le32_to_cpu(*scratch) & SS_STS_HANDSHAKE)) {
-			if (time_after(jiffies, before + MU_MAX_DELAY * HZ)) {
+			timeout = before + MU_MAX_DELAY * HZ;
+			if (time_after(jiffies, timeout)) {
 				printk(KERN_ERR DRV_NAME
 					"(%s): no signature after handshake frame\n",
 					pci_name(hba->pdev));
@@ -1196,7 +1201,8 @@ static int stex_ss_handshake(struct st_h
 	} else {
 		mailboxdata = readl(base + MAILBOX_BASE + MAILBOX_HNDSHK_STS);
 		while (mailboxdata != SS_STS_HANDSHAKE) {
-			if (time_after(jiffies, before + MU_MAX_DELAY * HZ)) {
+			timeout = before + MU_MAX_DELAY * HZ;
+			if (time_after(jiffies, timeout)) {
 				printk(KERN_ERR DRV_NAME
 					"(%s): no signature after handshake frame\n",
 					pci_name(hba->pdev));
@@ -1344,7 +1350,7 @@ static void stex_hard_reset(struct st_hb
 static int stex_yos_reset(struct st_hba *hba)
 {
 	void __iomem *base;
-	unsigned long flags, before;
+	unsigned long flags, before, timeout;
 	int ret = 0;
 
 	base = hba->mmio_base;
@@ -1352,7 +1358,8 @@ static int stex_yos_reset(struct st_hba
 	readl(base + IDBL); /* flush */
 	before = jiffies;
 	while (hba->out_req_cnt > 0) {
-		if (time_after(jiffies, before + ST_INTERNAL_TIMEOUT * HZ)) {
+		timeout = before + ST_INTERNAL_TIMEOUT * HZ;
+		if (time_after(jiffies, timeout)) {
 			printk(KERN_WARNING DRV_NAME
 				"(%s): reset timeout\n", pci_name(hba->pdev));
 			ret = -1;
@@ -1852,7 +1859,7 @@ static void stex_hba_stop(struct st_hba
 	struct req_msg *req;
 	struct st_msg_header *msg_h;
 	unsigned long flags;
-	unsigned long before;
+	unsigned long before, timeout;
 	u16 tag = 0;
 
 	spin_lock_irqsave(hba->host->host_lock, flags);
@@ -1899,7 +1906,8 @@ static void stex_hba_stop(struct st_hba
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 	before = jiffies;
 	while (hba->ccb[tag].req_type & PASSTHRU_REQ_TYPE) {
-		if (time_after(jiffies, before + ST_INTERNAL_TIMEOUT * HZ)) {
+		timeout = before + ST_INTERNAL_TIMEOUT * HZ;
+		if (time_after(jiffies, timeout)) {
 			hba->ccb[tag].req_type = 0;
 			hba->mu_status = MU_STATE_STOP;
 			return;