From 4ba54a6cbd4ddde805b769b4be04623a2ce1668c Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 11 Nov 2025 09:18:10 -1000 Subject: [PATCH] sched_ext: Refactor lockup handlers into handle_lockup() scx_rcu_cpu_stall() and scx_softlockup() share the same pattern: check if the scheduler is enabled under RCU read lock and trigger an error if so. Extract the common pattern into handle_lockup() helper. Add scx_verror() macro and use guard(rcu)(). This simplifies both handlers, reduces code duplication, and prepares for hardlockup handling. Reviewed-by: Dan Schatzberg Reviewed-by: Andrea Righi Cc: Emil Tsalapatis Signed-off-by: Tejun Heo --- kernel/sched/ext.c | 73 ++++++++++++++++++---------------------------- 1 file changed, 29 insertions(+), 44 deletions(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index e6e69a7fe105..ad5d3902e99d 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -192,6 +192,7 @@ static __printf(4, 5) bool scx_exit(struct scx_sched *sch, } #define scx_error(sch, fmt, args...) scx_exit((sch), SCX_EXIT_ERROR, 0, fmt, ##args) +#define scx_verror(sch, fmt, args) scx_vexit((sch), SCX_EXIT_ERROR, 0, fmt, args) #define SCX_HAS_OP(sch, op) test_bit(SCX_OP_IDX(op), (sch)->has_op) @@ -3654,6 +3655,29 @@ bool scx_allow_ttwu_queue(const struct task_struct *p) return false; } +static __printf(1, 2) bool handle_lockup(const char *fmt, ...) +{ + struct scx_sched *sch; + va_list args; + + guard(rcu)(); + + sch = rcu_dereference(scx_root); + if (unlikely(!sch)) + return false; + + switch (scx_enable_state()) { + case SCX_ENABLING: + case SCX_ENABLED: + va_start(args, fmt); + scx_verror(sch, fmt, args); + va_end(args); + return true; + default: + return false; + } +} + /** * scx_rcu_cpu_stall - sched_ext RCU CPU stall handler * @@ -3664,29 +3688,7 @@ bool scx_allow_ttwu_queue(const struct task_struct *p) */ bool scx_rcu_cpu_stall(void) { - struct scx_sched *sch; - - rcu_read_lock(); - - sch = rcu_dereference(scx_root); - if (unlikely(!sch)) { - rcu_read_unlock(); - return false; - } - - switch (scx_enable_state()) { - case SCX_ENABLING: - case SCX_ENABLED: - break; - default: - rcu_read_unlock(); - return false; - } - - scx_error(sch, "RCU CPU stall detected!"); - rcu_read_unlock(); - - return true; + return handle_lockup("RCU CPU stall detected!"); } /** @@ -3701,28 +3703,11 @@ bool scx_rcu_cpu_stall(void) */ void scx_softlockup(u32 dur_s) { - struct scx_sched *sch; + if (!handle_lockup("soft lockup - CPU %d stuck for %us", smp_processor_id(), dur_s)) + return; - rcu_read_lock(); - - sch = rcu_dereference(scx_root); - if (unlikely(!sch)) - goto out_unlock; - - switch (scx_enable_state()) { - case SCX_ENABLING: - case SCX_ENABLED: - break; - default: - goto out_unlock; - } - - printk_deferred(KERN_ERR "sched_ext: Soft lockup - CPU%d stuck for %us, disabling \"%s\"\n", - smp_processor_id(), dur_s, scx_root->ops.name); - - scx_error(sch, "soft lockup - CPU#%d stuck for %us", smp_processor_id(), dur_s); -out_unlock: - rcu_read_unlock(); + printk_deferred(KERN_ERR "sched_ext: Soft lockup - CPU %d stuck for %us, disabling BPF scheduler\n", + smp_processor_id(), dur_s); } /**