[PATCH AUTOSEL 6.15 064/118] rtla: Define __NR_sched_setattr for LoongArch

[Sasha Levin <sashal@kernel.org>]

From: Tiezhu Yang <yangtiezhu@loongson.cn>

[ Upstream commit 6a38c51a2557d4d50748818a858d507c250f3bee ]

When executing "make -C tools/tracing/rtla" on LoongArch, there exists
the following error:

  src/utils.c:237:24: error: '__NR_sched_setattr' undeclared

Just define __NR_sched_setattr for LoongArch if not exist.

Link: https://lore.kernel.org/20250422074917.25771-1-yangtiezhu@loongson.cn
Reported-by: Haiyong Sun <sunhaiyong@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

Based on my analysis of the commit and examination of the kernel source
tree, here is my assessment: **YES** This commit should be backported to
stable kernel trees for the following reasons: **1. Build Fix for
Supported Architecture**: This commit fixes a compilation error on
LoongArch architecture where `__NR_sched_setattr` is undeclared. The
error message shows: ``` src/utils.c:237:24: error: '__NR_sched_setattr'
undeclared ``` **2. Minimal and Safe Change**: The change adds just two
lines to define the syscall number for LoongArch: ```c # elif
__loongarch__ # define __NR_sched_setattr 274 ``` **3. Follows
Established Pattern**: From examining
`/home/sasha/linux/include/uapi/asm-generic/unistd.h`, I confirmed that
`__NR_sched_setattr` is indeed syscall number 274 in the generic syscall
table. LoongArch uses the generic syscall ABI (as evidenced by
`/home/sasha/linux/tools/arch/loongarch/include/uapi/asm/unistd.h`
including `asm-generic/unistd.h`), so using 274 is correct and
consistent. **4. Consistency with Similar Commits**: Looking at the
historical commits provided: - Similar Commit #5 (Status: NO) added
RISC-V support with the same syscall number 274 - Similar Commit #3
(Status: YES) was a build fix that removed unused functions - Similar
Commit #2 (Status: YES) fixed compilation issues with glibc The pattern
shows that build fixes for architecture support are typically backported
when they're minimal and safe. **5. Essential Functionality**: The rtla
tool is a real-time latency analysis tool that requires scheduler
attribute syscalls to function properly. Without this fix, the tool
cannot be built on LoongArch systems, making it completely unusable on
that architecture. **6. No Risk of Regression**: This change only
affects LoongArch builds and follows the exact same pattern used for
other architectures. It defines a constant that prevents compilation
failure without changing any runtime behavior. **7. Stable Tree Criteria
Met**: - Fixes an important build issue affecting users - Change is
minimal and contained - No architectural changes or new features -
Extremely low risk of regression - Follows established patterns The
commit perfectly fits the stable tree criteria for important bugfixes
with minimal risk.

 tools/tracing/rtla/src/utils.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/tracing/rtla/src/utils.c b/tools/tracing/rtla/src/utils.c
index 4995d35cf3ec6..d6ab15dcb4907 100644
--- a/tools/tracing/rtla/src/utils.c
+++ b/tools/tracing/rtla/src/utils.c
@@ -227,6 +227,8 @@ long parse_ns_duration(char *val)
 #  define __NR_sched_setattr	355
 # elif __s390x__
 #  define __NR_sched_setattr	345
+# elif __loongarch__
+#  define __NR_sched_setattr	274
 # endif
 #endif
 
-- 
2.39.5