[PATCH v2 1/1] sched_ext: Add error logging for dsq creation failures

[George Guo <dongtai.guo@linux.dev>]

From: George Guo <guodongtai@kylinos.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()

Signed-off-by: George Guo <guodongtai@kylinos.cn>
---
 tools/sched_ext/scx_central.bpf.c | 4 +++-
 tools/sched_ext/scx_flatcg.bpf.c  | 4 +++-
 tools/sched_ext/scx_qmap.bpf.c    | 8 ++++++--
 3 files changed, 12 insertions(+), 4 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 43126858b8e4..c216480c3ee0 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);
diff --git a/tools/sched_ext/scx_qmap.bpf.c b/tools/sched_ext/scx_qmap.bpf.c
index df21fad0c438..5fdd83769405 100644
--- a/tools/sched_ext/scx_qmap.bpf.c
+++ b/tools/sched_ext/scx_qmap.bpf.c
@@ -866,12 +866,16 @@ 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)
-- 
2.49.0