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authorThomas Gleixner <tglx@linutronix.de>2022-04-13 15:31:03 +0200
committerThomas Gleixner <tglx@linutronix.de>2022-05-01 10:03:43 +0200
commit16bf5a5e1ec56474ed2a19d72f272ed09a5d3ea1 (patch)
tree2b52b7341636f399a5495ccef71c6561e1d5632f /kernel/smp.c
parentd664e399128bd78b905ff480917e2c2d4949e101 (diff)
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smp: Rename flush_smp_call_function_from_idle()
This is invoked from the stopper thread too, which is definitely not idle. Rename it to flush_smp_call_function_queue() and fixup the callers. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20220413133024.305001096@linutronix.de
Diffstat (limited to 'kernel/smp.c')
-rw-r--r--kernel/smp.c27
1 files changed, 20 insertions, 7 deletions
diff --git a/kernel/smp.c b/kernel/smp.c
index 01a7c1706a58..8e85f22ed538 100644
--- 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;
}
@@ -541,11 +541,11 @@ 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'.
@@ -558,7 +558,7 @@ 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;
@@ -681,7 +681,20 @@ 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 long flags;
@@ -691,7 +704,7 @@ 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);
+ __flush_smp_call_function_queue(true);
if (local_softirq_pending())
do_softirq();