linux-kernel - [PATCH 1/1] sched_ext: Add error logging for dsq creation failures

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Message-ID: <20260107062851.82471-1-dongtai.guo@linux.dev>
Date: Wed,  7 Jan 2026 14:28:51 +0800
From: George Guo <dongtai.guo@...ux.dev>
To: tj@...nel.org,
	void@...ifault.com,
	arighi@...dia.com,
	changwoo@...lia.com
Cc: sched-ext@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	George Guo <guodongtai@...inos.cn>
Subject: [PATCH 1/1] sched_ext: Add error logging for dsq creation failures

From: George Guo <guodongtai@...inos.cn>

Add scx_bpf_error() calls when scx_bpf_create_dsq() fails in multiple
schedulers to improve debuggability:

- scx_central.bpf.c: central_init()
- scx_flatcg.bpf.c: fcg_cgroup_init() and fcg_init()
- scx_qmap.bpf.c: qmap_init()
- scx_simple.bpf.c: simple_init()

Signed-off-by: George Guo <guodongtai@...inos.cn>
---
 tools/sched_ext/scx_central.bpf.c |  4 +++-
 tools/sched_ext/scx_flatcg.bpf.c  | 12 ++++++++++--
 tools/sched_ext/scx_qmap.bpf.c    |  8 ++++++--
 tools/sched_ext/scx_simple.bpf.c  |  8 +++++++-
 4 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/tools/sched_ext/scx_central.bpf.c b/tools/sched_ext/scx_central.bpf.c
index 55df8b798865..1c2376b75b5d 100644
--- a/tools/sched_ext/scx_central.bpf.c
+++ b/tools/sched_ext/scx_central.bpf.c
@@ -301,8 +301,10 @@ int BPF_STRUCT_OPS_SLEEPABLE(central_init)
 	int ret;
 
 	ret = scx_bpf_create_dsq(FALLBACK_DSQ_ID, -1);
-	if (ret)
+	if (ret) {
+		scx_bpf_error("scx_bpf_create_dsq failed (%d)", ret);
 		return ret;
+	}
 
 	timer = bpf_map_lookup_elem(&central_timer, &key);
 	if (!timer)
diff --git a/tools/sched_ext/scx_flatcg.bpf.c b/tools/sched_ext/scx_flatcg.bpf.c
index 2c720e3ecad5..f7830e14b9af 100644
--- a/tools/sched_ext/scx_flatcg.bpf.c
+++ b/tools/sched_ext/scx_flatcg.bpf.c
@@ -842,8 +842,10 @@ int BPF_STRUCT_OPS_SLEEPABLE(fcg_cgroup_init, struct cgroup *cgrp,
 	 * unlikely case that it breaks.
 	 */
 	ret = scx_bpf_create_dsq(cgid, -1);
-	if (ret)
+	if (ret) {
+		scx_bpf_error("scx_bpf_create_dsq failed (%d)", ret);
 		return ret;
+	}
 
 	cgc = bpf_cgrp_storage_get(&cgrp_ctx, cgrp, 0,
 				   BPF_LOCAL_STORAGE_GET_F_CREATE);
@@ -927,7 +929,13 @@ void BPF_STRUCT_OPS(fcg_cgroup_move, struct task_struct *p,
 
 s32 BPF_STRUCT_OPS_SLEEPABLE(fcg_init)
 {
-	return scx_bpf_create_dsq(FALLBACK_DSQ, -1);
+	s32 ret;
+
+	ret = scx_bpf_create_dsq(FALLBACK_DSQ, -1);
+	if (ret)
+		scx_bpf_error("scx_bpf_create_dsq failed (%d)", ret);
+
+	return ret;
 }
 
 void BPF_STRUCT_OPS(fcg_exit, struct scx_exit_info *ei)
diff --git a/tools/sched_ext/scx_qmap.bpf.c b/tools/sched_ext/scx_qmap.bpf.c
index 3072b593f898..16ed8f867ad9 100644
--- a/tools/sched_ext/scx_qmap.bpf.c
+++ b/tools/sched_ext/scx_qmap.bpf.c
@@ -852,12 +852,16 @@ s32 BPF_STRUCT_OPS_SLEEPABLE(qmap_init)
 		print_cpus();
 
 	ret = scx_bpf_create_dsq(SHARED_DSQ, -1);
-	if (ret)
+	if (ret) {
+		scx_bpf_error("scx_bpf_create_dsq failed (%d)", ret);
 		return ret;
+	}
 
 	ret = scx_bpf_create_dsq(HIGHPRI_DSQ, -1);
-	if (ret)
+	if (ret) {
+		scx_bpf_error("scx_bpf_create_dsq failed (%d)", ret);
 		return ret;
+	}
 
 	timer = bpf_map_lookup_elem(&monitor_timer, &key);
 	if (!timer)
diff --git a/tools/sched_ext/scx_simple.bpf.c b/tools/sched_ext/scx_simple.bpf.c
index e6de99dba7db..50e4555459de 100644
--- a/tools/sched_ext/scx_simple.bpf.c
+++ b/tools/sched_ext/scx_simple.bpf.c
@@ -131,7 +131,13 @@ void BPF_STRUCT_OPS(simple_enable, struct task_struct *p)
 
 s32 BPF_STRUCT_OPS_SLEEPABLE(simple_init)
 {
-	return scx_bpf_create_dsq(SHARED_DSQ, -1);
+	s32 ret;
+
+	ret = scx_bpf_create_dsq(SHARED_DSQ, -1);
+	if (ret)
+		scx_bpf_error("scx_bpf_create_dsq failed (%d)", ret);
+
+	return ret;
 }
 
 void BPF_STRUCT_OPS(simple_exit, struct scx_exit_info *ei)
-- 
2.43.0