tick_handover_do_timer() which is invoked when a CPU is unplugged has a check for cpumask_first(cpu_online_mask) when it tries to hand over the tick update duty. Checking the result of cpumask_first() there is pointless because if the online mask is empty at this point, then this would be the last CPU in the system going offline, which is impossible. There is always at least one CPU remaining. If online mask would be really empty then the timer duty would be the least of the resulting problems. Remove the well meant check simply because it is pointless and confusing.
Unified · Split
| @@ -407,17 +407,13 @@ EXPORT_SYMBOL_GPL(tick_broadcast_oneshot_control); · 406 unmodified lines | |||
| 407 | /* | 407 | /* |
| 408 | * Transfer the do_timer job away from a dying cpu. | 408 | * Transfer the do_timer job away from a dying cpu. |
| 409 | * | 409 | * |
| 410 | * Called with interrupts disabled. Not locking required. If | 410 | * Called with interrupts disabled. No locking required. If |
| 411 | * tick_do_timer_cpu is owned by this cpu, nothing can change it. | 411 | * tick_do_timer_cpu is owned by this cpu, nothing can change it. |
| 412 | */ | 412 | */ |
| 413 | void tick_handover_do_timer(void) | 413 | void tick_handover_do_timer(void) |
| 414 | { | 414 | { |
| 415 | if (tick_do_timer_cpu == smp_processor_id()) { | 415 | if (tick_do_timer_cpu == smp_processor_id()) |
| 416 | int cpu = cpumask_first(cpu_online_mask); | 416 | tick_do_timer_cpu = cpumask_first(cpu_online_mask); |
| 417 | |||
| 418 | tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu : | ||
| 419 | TICK_DO_TIMER_NONE; | ||
| 420 | } | ||
| 421 | } | 417 | } |
| 422 | 418 | ||
| 423 | /* | 419 | /* |