Merge tag 'sched_ext-for-6.15-rc0-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext

Pull sched_ext fixes from Tejun Heo:

 - Calling scx_bpf_create_dsq() with the same ID would succeed creating
   duplicate DSQs. Fix it to return -EEXIST.

 - scx_select_cpu_dfl() fixes and cleanups.

 - Synchronize tool/sched_ext with external scheduler repo. While this
   isn't a fix. There's no risk to the kernel and it's better if they
   stay synced closer.

* tag 'sched_ext-for-6.15-rc0-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
  tools/sched_ext: Sync with scx repo
  sched_ext: initialize built-in idle state before ops.init()
  sched_ext: create_dsq: Return -EEXIST on duplicate request
  sched_ext: Remove a meaningless conditional goto in scx_select_cpu_dfl()
  sched_ext: idle: Fix return code of scx_select_cpu_dfl()

Author: torvalds

kernel/sched/ext.c

@@ -4171,8 +4171,8 @@ static struct scx_dispatch_q *create_dsq(u64 dsq_id, int node)
 
 	init_dsq(dsq, dsq_id);
 
-	ret = rhashtable_insert_fast(&dsq_hash, &dsq->hash_node,
-				     dsq_hash_params);
+	ret = rhashtable_lookup_insert_fast(&dsq_hash, &dsq->hash_node,
+					    dsq_hash_params);
 	if (ret) {
 		kfree(dsq);
 		return ERR_PTR(ret);
@@ -5361,6 +5361,8 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link)
 	 */
 	cpus_read_lock();
 
+	scx_idle_enable(ops);
+
 	if (scx_ops.init) {
 		ret = SCX_CALL_OP_RET(SCX_KF_UNLOCKED, init);
 		if (ret) {
@@ -5427,8 +5429,6 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link)
 	if (scx_ops.cpu_acquire || scx_ops.cpu_release)
 		static_branch_enable(&scx_ops_cpu_preempt);
 
-	scx_idle_enable(ops);
-
 	/*
 	 * Lock out forks, cgroup on/offlining and moves before opening the
 	 * floodgate so that they don't wander into the operations prematurely.

kernel/sched/ext_idle.c

@@ -544,7 +544,7 @@ s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags, u64
 		 * core.
 		 */
 		if (flags & SCX_PICK_IDLE_CORE) {
-			cpu = prev_cpu;
+			cpu = -EBUSY;
 			goto out_unlock;
 		}
 	}
@@ -584,8 +584,6 @@ s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags, u64
 	 * increasing distance.
 	 */
 	cpu = scx_pick_idle_cpu(p->cpus_ptr, node, flags);
-	if (cpu >= 0)
-		goto out_unlock;
 
 out_unlock:
 	rcu_read_unlock();
@@ -723,14 +721,14 @@ static void reset_idle_masks(struct sched_ext_ops *ops)
 void scx_idle_enable(struct sched_ext_ops *ops)
 {
 	if (!ops->update_idle || (ops->flags & SCX_OPS_KEEP_BUILTIN_IDLE))
-		static_branch_enable(&scx_builtin_idle_enabled);
+		static_branch_enable_cpuslocked(&scx_builtin_idle_enabled);
 	else
-		static_branch_disable(&scx_builtin_idle_enabled);
+		static_branch_disable_cpuslocked(&scx_builtin_idle_enabled);
 
 	if (ops->flags & SCX_OPS_BUILTIN_IDLE_PER_NODE)
-		static_branch_enable(&scx_builtin_idle_per_node);
+		static_branch_enable_cpuslocked(&scx_builtin_idle_per_node);
 	else
-		static_branch_disable(&scx_builtin_idle_per_node);
+		static_branch_disable_cpuslocked(&scx_builtin_idle_per_node);
 
 #ifdef CONFIG_SMP
 	reset_idle_masks(ops);

tools/sched_ext/include/scx/common.bpf.h

@@ -586,36 +586,48 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
 	}
 }
 
-#define READ_ONCE(x)					\
-({							\
-	union { typeof(x) __val; char __c[1]; } __u =	\
-		{ .__c = { 0 } };			\
-	__read_once_size(&(x), __u.__c, sizeof(x));	\
-	__u.__val;					\
-})
-
-#define WRITE_ONCE(x, val)				\
-({							\
-	union { typeof(x) __val; char __c[1]; } __u =	\
-		{ .__val = (val) }; 			\
-	__write_once_size(&(x), __u.__c, sizeof(x));	\
-	__u.__val;					\
-})
-
-#define READ_ONCE_ARENA(type, x)				\
-({								\
-	union { type __val; char __c[1]; } __u =		\
-		{ .__c = { 0 } };				\
-	__read_once_size((void *)&(x), __u.__c, sizeof(x));	\
-	__u.__val;						\
+/*
+ * __unqual_typeof(x) - Declare an unqualified scalar type, leaving
+ *			non-scalar types unchanged,
+ *
+ * Prefer C11 _Generic for better compile-times and simpler code. Note: 'char'
+ * is not type-compatible with 'signed char', and we define a separate case.
+ *
+ * This is copied verbatim from kernel's include/linux/compiler_types.h, but
+ * with default expression (for pointers) changed from (x) to (typeof(x)0).
+ *
+ * This is because LLVM has a bug where for lvalue (x), it does not get rid of
+ * an extra address_space qualifier, but does in case of rvalue (typeof(x)0).
+ * Hence, for pointers, we need to create an rvalue expression to get the
+ * desired type. See https://github.com/llvm/llvm-project/issues/53400.
+ */
+#define __scalar_type_to_expr_cases(type) \
+	unsigned type : (unsigned type)0, signed type : (signed type)0
+
+#define __unqual_typeof(x)                              \
+	typeof(_Generic((x),                            \
+		char: (char)0,                          \
+		__scalar_type_to_expr_cases(char),      \
+		__scalar_type_to_expr_cases(short),     \
+		__scalar_type_to_expr_cases(int),       \
+		__scalar_type_to_expr_cases(long),      \
+		__scalar_type_to_expr_cases(long long), \
+		default: (typeof(x))0))
+
+#define READ_ONCE(x)								\
+({										\
+	union { __unqual_typeof(x) __val; char __c[1]; } __u =			\
+		{ .__c = { 0 } };						\
+	__read_once_size((__unqual_typeof(x) *)&(x), __u.__c, sizeof(x));	\
+	__u.__val;								\
 })
 
-#define WRITE_ONCE_ARENA(type, x, val)				\
-({								\
-	union { type __val; char __c[1]; } __u =		\
-		{ .__val = (val) }; 				\
-	__write_once_size((void *)&(x), __u.__c, sizeof(x));	\
-	__u.__val;						\
+#define WRITE_ONCE(x, val)							\
+({										\
+	union { __unqual_typeof(x) __val; char __c[1]; } __u =			\
+		{ .__val = (val) }; 						\
+	__write_once_size((__unqual_typeof(x) *)&(x), __u.__c, sizeof(x));	\
+	__u.__val;								\
 })
 
 /*
@@ -648,6 +660,23 @@ static inline u32 log2_u64(u64 v)
                 return log2_u32(v) + 1;
 }
 
+/*
+ * Return a value proportionally scaled to the task's weight.
+ */
+static inline u64 scale_by_task_weight(const struct task_struct *p, u64 value)
+{
+	return (value * p->scx.weight) / 100;
+}
+
+/*
+ * Return a value inversely proportional to the task's weight.
+ */
+static inline u64 scale_by_task_weight_inverse(const struct task_struct *p, u64 value)
+{
+	return value * 100 / p->scx.weight;
+}
+
+
 #include "compat.bpf.h"
 #include "enums.bpf.h"
 

tools/sched_ext/include/scx/enum_defs.autogen.h

@@ -88,6 +88,8 @@
 #define HAVE_SCX_OPS_ENQ_LAST
 #define HAVE_SCX_OPS_ENQ_EXITING
 #define HAVE_SCX_OPS_SWITCH_PARTIAL
+#define HAVE_SCX_OPS_ENQ_MIGRATION_DISABLED
+#define HAVE_SCX_OPS_ALLOW_QUEUED_WAKEUP
 #define HAVE_SCX_OPS_HAS_CGROUP_WEIGHT
 #define HAVE_SCX_OPS_ALL_FLAGS
 #define HAVE_SCX_OPSS_NONE
@@ -104,6 +106,7 @@
 #define HAVE_SCX_RQ_BAL_PENDING
 #define HAVE_SCX_RQ_BAL_KEEP
 #define HAVE_SCX_RQ_BYPASSING
+#define HAVE_SCX_RQ_CLK_VALID
 #define HAVE_SCX_RQ_IN_WAKEUP
 #define HAVE_SCX_RQ_IN_BALANCE
 #define HAVE_SCX_TASK_NONE

tools/sched_ext/include/scx/enums.autogen.bpf.h

@@ -13,6 +13,30 @@ const volatile u64 __SCX_SLICE_DFL __weak;
 const volatile u64 __SCX_SLICE_INF __weak;
 #define SCX_SLICE_INF __SCX_SLICE_INF
 
+const volatile u64 __SCX_RQ_ONLINE __weak;
+#define SCX_RQ_ONLINE __SCX_RQ_ONLINE
+
+const volatile u64 __SCX_RQ_CAN_STOP_TICK __weak;
+#define SCX_RQ_CAN_STOP_TICK __SCX_RQ_CAN_STOP_TICK
+
+const volatile u64 __SCX_RQ_BAL_PENDING __weak;
+#define SCX_RQ_BAL_PENDING __SCX_RQ_BAL_PENDING
+
+const volatile u64 __SCX_RQ_BAL_KEEP __weak;
+#define SCX_RQ_BAL_KEEP __SCX_RQ_BAL_KEEP
+
+const volatile u64 __SCX_RQ_BYPASSING __weak;
+#define SCX_RQ_BYPASSING __SCX_RQ_BYPASSING
+
+const volatile u64 __SCX_RQ_CLK_VALID __weak;
+#define SCX_RQ_CLK_VALID __SCX_RQ_CLK_VALID
+
+const volatile u64 __SCX_RQ_IN_WAKEUP __weak;
+#define SCX_RQ_IN_WAKEUP __SCX_RQ_IN_WAKEUP
+
+const volatile u64 __SCX_RQ_IN_BALANCE __weak;
+#define SCX_RQ_IN_BALANCE __SCX_RQ_IN_BALANCE
+
 const volatile u64 __SCX_DSQ_FLAG_BUILTIN __weak;
 #define SCX_DSQ_FLAG_BUILTIN __SCX_DSQ_FLAG_BUILTIN
 

tools/sched_ext/include/scx/enums.autogen.h

@@ -8,6 +8,14 @@
 	SCX_ENUM_SET(skel, scx_public_consts, SCX_OPS_NAME_LEN); \
 	SCX_ENUM_SET(skel, scx_public_consts, SCX_SLICE_DFL); \
 	SCX_ENUM_SET(skel, scx_public_consts, SCX_SLICE_INF); \
+	SCX_ENUM_SET(skel, scx_rq_flags, SCX_RQ_ONLINE); \
+	SCX_ENUM_SET(skel, scx_rq_flags, SCX_RQ_CAN_STOP_TICK); \
+	SCX_ENUM_SET(skel, scx_rq_flags, SCX_RQ_BAL_PENDING); \
+	SCX_ENUM_SET(skel, scx_rq_flags, SCX_RQ_BAL_KEEP); \
+	SCX_ENUM_SET(skel, scx_rq_flags, SCX_RQ_BYPASSING); \
+	SCX_ENUM_SET(skel, scx_rq_flags, SCX_RQ_CLK_VALID); \
+	SCX_ENUM_SET(skel, scx_rq_flags, SCX_RQ_IN_WAKEUP); \
+	SCX_ENUM_SET(skel, scx_rq_flags, SCX_RQ_IN_BALANCE); \
 	SCX_ENUM_SET(skel, scx_dsq_id_flags, SCX_DSQ_FLAG_BUILTIN); \
 	SCX_ENUM_SET(skel, scx_dsq_id_flags, SCX_DSQ_FLAG_LOCAL_ON); \
 	SCX_ENUM_SET(skel, scx_dsq_id_flags, SCX_DSQ_INVALID); \

tools/sched_ext/include/scx/enums.h

@@ -14,7 +14,8 @@ static inline void __ENUM_set(u64 *val, char *type, char *name)
 	bool res;
 
 	res = __COMPAT_read_enum(type, name, val);
-	SCX_BUG_ON(!res, "enum not found(%s)", name);
+	if (!res)
+		*val = 0;
 }
 
 #define SCX_ENUM_SET(skel, type, name) do {			\