Merge tag 'sched-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git...

[linux-2.6-microblaze.git] / kernel / smp.c

diff --git a/kernel/smp.c b/kernel/smp.c
index df9393a..dd215f4 100644 (file)
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -96,7 +96,7 @@ static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data);
 
 static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);
 
-static void flush_smp_call_function_queue(bool warn_cpu_offline);
+static void __flush_smp_call_function_queue(bool warn_cpu_offline);
 
 int smpcfd_prepare_cpu(unsigned int cpu)
 {
@@ -141,7 +141,7 @@ int smpcfd_dying_cpu(unsigned int cpu)
         * ensure that the outgoing CPU doesn't go offline with work
         * still pending.
         */
-       flush_smp_call_function_queue(false);
+       __flush_smp_call_function_queue(false);
        irq_work_run();
        return 0;
 }
@@ -544,11 +544,11 @@ void generic_smp_call_function_single_interrupt(void)
 {
        cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->gotipi, CFD_SEQ_NOCPU,
                      smp_processor_id(), CFD_SEQ_GOTIPI);
-       flush_smp_call_function_queue(true);
+       __flush_smp_call_function_queue(true);
 }
 
 /**
- * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
+ * __flush_smp_call_function_queue - Flush pending smp-call-function callbacks
  *
  * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
  *                   offline CPU. Skip this check if set to 'false'.
@@ -561,7 +561,7 @@ void generic_smp_call_function_single_interrupt(void)
  * Loop through the call_single_queue and run all the queued callbacks.
  * Must be called with interrupts disabled.
  */
-static void flush_smp_call_function_queue(bool warn_cpu_offline)
+static void __flush_smp_call_function_queue(bool warn_cpu_offline)
 {
        call_single_data_t *csd, *csd_next;
        struct llist_node *entry, *prev;
@@ -684,8 +684,22 @@ static void flush_smp_call_function_queue(bool warn_cpu_offline)
                      smp_processor_id(), CFD_SEQ_HDLEND);
 }
 
-void flush_smp_call_function_from_idle(void)
+
+/**
+ * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
+ *                                from task context (idle, migration thread)
+ *
+ * When TIF_POLLING_NRFLAG is supported and a CPU is in idle and has it
+ * set, then remote CPUs can avoid sending IPIs and wake the idle CPU by
+ * setting TIF_NEED_RESCHED. The idle task on the woken up CPU has to
+ * handle queued SMP function calls before scheduling.
+ *
+ * The migration thread has to ensure that an eventually pending wakeup has
+ * been handled before it migrates a task.
+ */
+void flush_smp_call_function_queue(void)
 {
+       unsigned int was_pending;
        unsigned long flags;
 
        if (llist_empty(this_cpu_ptr(&call_single_queue)))
@@ -694,9 +708,11 @@ void flush_smp_call_function_from_idle(void)
        cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->idle, CFD_SEQ_NOCPU,
                      smp_processor_id(), CFD_SEQ_IDLE);
        local_irq_save(flags);
-       flush_smp_call_function_queue(true);
+       /* Get the already pending soft interrupts for RT enabled kernels */
+       was_pending = local_softirq_pending();
+       __flush_smp_call_function_queue(true);
        if (local_softirq_pending())
-               do_softirq();
+               do_softirq_post_smp_call_flush(was_pending);
 
        local_irq_restore(flags);
 }