From: Thomas Weißschuh <linux@weissschuh.net>
Date: Thu, 2 Apr 2026 14:36:19 +0000 (+0200)
Subject: checksyscalls: only run when necessary
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b34db3fa85c4d34ceee5231cd27e587153bc25ab;p=thirdparty%2Flinux.git

checksyscalls: only run when necessary

Currently checksyscalls.sh is unconditionally executed during each build.
Most of these executions are unnecessary.

Only run checksyscalls.sh if one of its inputs have changed.

This new logic does not work for the multiple invocations done for MIPS.
The effect is that checksyscalls.sh is still executed unconditionally.
However this is not worse than before.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Link: https://patch.msgid.link/20260402-kbuild-missing-syscalls-v3-2-6641be1de2db@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
---

diff --git a/Kbuild b/Kbuild
index 13324b4bbe236..515cc6a27477f 100644
--- a/Kbuild
+++ b/Kbuild
@@ -47,12 +47,18 @@ $(rq-offsets-file): kernel/sched/rq-offsets.s FORCE
 
 # Check for missing system calls
 
+missing-syscalls-file := .tmp_missing-syscalls
+
+targets += $(missing-syscalls-file)
+
 quiet_cmd_syscalls = CALL    $<
-      cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags) $(missing_syscalls_flags)
+      cmd_syscalls = DEPFILE=$(depfile) $(CONFIG_SHELL) $< $(CC) $(c_flags) $(missing_syscalls_flags); touch $@
+
+$(missing-syscalls-file): scripts/checksyscalls.sh $(rq-offsets-file) FORCE
+	$(call if_changed_dep,syscalls)
 
 PHONY += missing-syscalls
-missing-syscalls: scripts/checksyscalls.sh $(rq-offsets-file)
-	$(call cmd,syscalls)
+missing-syscalls: $(missing-syscalls-file)
 
 # Check the manual modification of atomic headers
 
diff --git a/scripts/checksyscalls.sh b/scripts/checksyscalls.sh
index b2ab3b1d76b84..e2970421c1fff 100755
--- a/scripts/checksyscalls.sh
+++ b/scripts/checksyscalls.sh
@@ -275,3 +275,8 @@ syscall_list() {
 
 (ignore_list && syscall_list ${reference_table}) | \
 $* -Wno-error -Wno-unused-macros -E -x c - > /dev/null
+
+# For fixdep
+if [ -n "${DEPFILE}" ]; then
+	echo "${0}: ${0} ${reference_table}" >> "${DEPFILE}"
+fi