linux-kernel - [PATCH] tools/nolibc: avoid using plain integer as NULL pointer

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Message-Id: <20251109-nolibc-sparse-v1-1-02256638a99c@weissschuh.net>
Date: Sun, 09 Nov 2025 20:27:29 +0100
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Willy Tarreau <w@....eu>
Cc: linux-kernel@...r.kernel.org, kernel test robot <lkp@...el.com>, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH] tools/nolibc: avoid using plain integer as NULL pointer

The integer zero should not be used as NULL pointer.
It is invalid and sparse will complain about it.

Use proper NULL pointers instead.

Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/r/202509261452.g5peaXCc-lkp@intel.com/
Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 tools/include/nolibc/getopt.h     | 2 +-
 tools/include/nolibc/sys.h        | 2 +-
 tools/include/nolibc/sys/reboot.h | 2 +-
 tools/include/nolibc/unistd.h     | 6 +++---
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/tools/include/nolibc/getopt.h b/tools/include/nolibc/getopt.h
index 217abb95264b..87565e3b6a33 100644
--- a/tools/include/nolibc/getopt.h
+++ b/tools/include/nolibc/getopt.h
@@ -78,7 +78,7 @@ int getopt(int argc, char * const argv[], const char *optstring)
 		return '?';
 	}
 	if (optstring[i] == ':') {
-		optarg = 0;
+		optarg = NULL;
 		if (optstring[i + 1] != ':' || __optpos) {
 			optarg = argv[optind++];
 			if (__optpos)
diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
index 28481feedb37..fcc36cffad4d 100644
--- a/tools/include/nolibc/sys.h
+++ b/tools/include/nolibc/sys.h
@@ -106,7 +106,7 @@ static __attribute__((unused))
 void *sbrk(intptr_t inc)
 {
 	/* first call to find current end */
-	void *ret = sys_brk(0);
+	void *ret = sys_brk(NULL);
 
 	if (ret && sys_brk(ret + inc) == ret + inc)
 		return ret + inc;
diff --git a/tools/include/nolibc/sys/reboot.h b/tools/include/nolibc/sys/reboot.h
index 4a1e435be669..38274c64a722 100644
--- a/tools/include/nolibc/sys/reboot.h
+++ b/tools/include/nolibc/sys/reboot.h
@@ -28,7 +28,7 @@ ssize_t sys_reboot(int magic1, int magic2, int cmd, void *arg)
 static __attribute__((unused))
 int reboot(int cmd)
 {
-	return __sysret(sys_reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, cmd, 0));
+	return __sysret(sys_reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, cmd, NULL));
 }
 
 #endif /* _NOLIBC_SYS_REBOOT_H */
diff --git a/tools/include/nolibc/unistd.h b/tools/include/nolibc/unistd.h
index 7405fa2b89ba..bb5e80f3f05d 100644
--- a/tools/include/nolibc/unistd.h
+++ b/tools/include/nolibc/unistd.h
@@ -54,7 +54,7 @@ int msleep(unsigned int msecs)
 {
 	struct timeval my_timeval = { msecs / 1000, (msecs % 1000) * 1000 };
 
-	if (sys_select(0, 0, 0, 0, &my_timeval) < 0)
+	if (sys_select(0, NULL, NULL, NULL, &my_timeval) < 0)
 		return (my_timeval.tv_sec * 1000) +
 			(my_timeval.tv_usec / 1000) +
 			!!(my_timeval.tv_usec % 1000);
@@ -67,7 +67,7 @@ unsigned int sleep(unsigned int seconds)
 {
 	struct timeval my_timeval = { seconds, 0 };
 
-	if (sys_select(0, 0, 0, 0, &my_timeval) < 0)
+	if (sys_select(0, NULL, NULL, NULL, &my_timeval) < 0)
 		return my_timeval.tv_sec + !!my_timeval.tv_usec;
 	else
 		return 0;
@@ -78,7 +78,7 @@ int usleep(unsigned int usecs)
 {
 	struct timeval my_timeval = { usecs / 1000000, usecs % 1000000 };
 
-	return sys_select(0, 0, 0, 0, &my_timeval);
+	return sys_select(0, NULL, NULL, NULL, &my_timeval);
 }
 
 static __attribute__((unused))

---
base-commit: 107eb8336e8782ae8e98b60962852a1e29aca715
change-id: 20251027-nolibc-sparse-c14fe0619edc

Best regards,
-- 
Thomas Weißschuh <linux@...ssschuh.net>