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 <[email protected]>
---
V4: New patch
---
kernel/sched/core.c | 2 +-
kernel/sched/idle.c | 2 +-
kernel/sched/sched.h | 4 ++--
kernel/smp.c | 27 ++++++++++++++++++++-------
4 files changed, 24 insertions(+), 11 deletions(-)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2408,7 +2408,7 @@ static int migration_cpu_stop(void *data
* __migrate_task() such that we will not miss enforcing cpus_ptr
* during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
*/
- flush_smp_call_function_from_idle();
+ flush_smp_call_function_queue();
raw_spin_lock(&p->pi_lock);
rq_lock(rq, &rf);
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -327,7 +327,7 @@ static void do_idle(void)
* RCU relies on this call to be done outside of an RCU read-side
* critical section.
*/
- flush_smp_call_function_from_idle();
+ flush_smp_call_function_queue();
schedule_idle();
if (unlikely(klp_patch_pending(current)))
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1834,10 +1834,10 @@ static inline void dirty_sched_domain_sy
extern int sched_update_scaling(void);
-extern void flush_smp_call_function_from_idle(void);
+extern void flush_smp_call_function_queue(void);
#else /* !CONFIG_SMP: */
-static inline void flush_smp_call_function_from_idle(void) { }
+static inline void flush_smp_call_function_queue(void) { }
#endif
#include "stats.h"
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -96,7 +96,7 @@ static DEFINE_PER_CPU_ALIGNED(struct cal
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_in
{
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_in
* 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_queu
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(v
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();
Hi Thomas,
I love your patch! Perhaps something to improve:
[auto build test WARNING on tip/sched/core]
[also build test WARNING on hch-configfs/for-next linus/master linux/master v5.18-rc2 next-20220412]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/intel-lab-lkp/linux/commits/Thomas-Gleixner/smp-Make-softirq-handling-RT-friendly/20220413-045944
base: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 089c02ae2771a14af2928c59c56abfb9b885a8d7
config: hexagon-defconfig (https://download.01.org/0day-ci/archive/20220413/[email protected]/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project fe2478d44e4f7f191c43fef629ac7a23d0251e72)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/7c7c3b99f3599eb409f237b32f330fa06bffcd5d
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Thomas-Gleixner/smp-Make-softirq-handling-RT-friendly/20220413-045944
git checkout 7c7c3b99f3599eb409f237b32f330fa06bffcd5d
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
All warnings (new ones prefixed by >>):
>> kernel/smp.c:697:6: warning: no previous prototype for function 'flush_smp_call_function_queue' [-Wmissing-prototypes]
void flush_smp_call_function_queue(void)
^
kernel/smp.c:697:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
void flush_smp_call_function_queue(void)
^
static
1 warning generated.
vim +/flush_smp_call_function_queue +697 kernel/smp.c
683
684
685 /**
686 * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
687 * from task context (idle, migration thread)
688 *
689 * When TIF_POLLING_NRFLAG is supported and a CPU is in idle and has it
690 * set, then remote CPUs can avoid sending IPIs and wake the idle CPU by
691 * setting TIF_NEED_RESCHED. The idle task on the woken up CPU has to
692 * handle queued SMP function calls before scheduling.
693 *
694 * The migration thread has to ensure that an eventually pending wakeup has
695 * been handled before it migrates a task.
696 */
> 697 void flush_smp_call_function_queue(void)
698 {
699 unsigned long flags;
700
701 if (llist_empty(this_cpu_ptr(&call_single_queue)))
702 return;
703
704 cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->idle, CFD_SEQ_NOCPU,
705 smp_processor_id(), CFD_SEQ_IDLE);
706 local_irq_save(flags);
707 __flush_smp_call_function_queue(true);
708 if (local_softirq_pending())
709 do_softirq();
710
711 local_irq_restore(flags);
712 }
713
--
0-DAY CI Kernel Test Service
https://01.org/lkp
Hi Thomas,
I love your patch! Perhaps something to improve:
[auto build test WARNING on tip/sched/core]
[also build test WARNING on hch-configfs/for-next linus/master linux/master v5.18-rc2 next-20220412]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/intel-lab-lkp/linux/commits/Thomas-Gleixner/smp-Make-softirq-handling-RT-friendly/20220413-045944
base: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 089c02ae2771a14af2928c59c56abfb9b885a8d7
config: arc-defconfig (https://download.01.org/0day-ci/archive/20220413/[email protected]/config)
compiler: arc-elf-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/7c7c3b99f3599eb409f237b32f330fa06bffcd5d
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Thomas-Gleixner/smp-Make-softirq-handling-RT-friendly/20220413-045944
git checkout 7c7c3b99f3599eb409f237b32f330fa06bffcd5d
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=arc SHELL=/bin/bash
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
All warnings (new ones prefixed by >>):
>> kernel/smp.c:697:6: warning: no previous prototype for 'flush_smp_call_function_queue' [-Wmissing-prototypes]
697 | void flush_smp_call_function_queue(void)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
vim +/flush_smp_call_function_queue +697 kernel/smp.c
683
684
685 /**
686 * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
687 * from task context (idle, migration thread)
688 *
689 * When TIF_POLLING_NRFLAG is supported and a CPU is in idle and has it
690 * set, then remote CPUs can avoid sending IPIs and wake the idle CPU by
691 * setting TIF_NEED_RESCHED. The idle task on the woken up CPU has to
692 * handle queued SMP function calls before scheduling.
693 *
694 * The migration thread has to ensure that an eventually pending wakeup has
695 * been handled before it migrates a task.
696 */
> 697 void flush_smp_call_function_queue(void)
698 {
699 unsigned long flags;
700
701 if (llist_empty(this_cpu_ptr(&call_single_queue)))
702 return;
703
704 cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->idle, CFD_SEQ_NOCPU,
705 smp_processor_id(), CFD_SEQ_IDLE);
706 local_irq_save(flags);
707 __flush_smp_call_function_queue(true);
708 if (local_softirq_pending())
709 do_softirq();
710
711 local_irq_restore(flags);
712 }
713
--
0-DAY CI Kernel Test Service
https://01.org/lkp
On Wed, Apr 13 2022 at 10:52, kernel test robot wrote:
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <[email protected]>
>
> All warnings (new ones prefixed by >>):
>
>>> kernel/smp.c:697:6: warning: no previous prototype for 'flush_smp_call_function_queue' [-Wmissing-prototypes]
> 697 | void flush_smp_call_function_queue(void)
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This is not really new. It's "new" because the function was renamed.
I'll fix the whole pile of preexisting warnings which are related to
kernel/sched/*.
Thanks,
tglx