From: "Paul E. McKenney" <paulmck@xxxxxxxxxx> This commit adds a destination CPU to __call_single_data, and is inspired by an earlier commit by Peter Zijlstra. This version adds #ifdef to permit use by 32-bit systems and supplying the destination CPU for all smp_call_function*() requests, not just smp_call_function_single(). If need be, 32-bit systems could be accommodated by shrinking the flags field to 16 bits (the atomic_t variant is currently unused) and by providing only eight bits for CPU on such systems. It is not clear that the addition of the fields to __call_single_node are really needed. Link: https://lore.kernel.org/lkml/20200615164048.GC2531@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Cc: Frederic Weisbecker <frederic@xxxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- include/linux/smp.h | 3 +++ include/linux/smp_types.h | 3 +++ kernel/smp.c | 2 ++ 3 files changed, 8 insertions(+) diff --git a/include/linux/smp.h b/include/linux/smp.h index 80d557e..9f13966 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -26,6 +26,9 @@ struct __call_single_data { struct { struct llist_node llist; unsigned int flags; +#ifdef CONFIG_64BIT + u16 src, dst; +#endif }; }; smp_call_func_t func; diff --git a/include/linux/smp_types.h b/include/linux/smp_types.h index 364b3ae..2e8461a 100644 --- a/include/linux/smp_types.h +++ b/include/linux/smp_types.h @@ -61,6 +61,9 @@ struct __call_single_node { unsigned int u_flags; atomic_t a_flags; }; +#ifdef CONFIG_64BIT + u16 src, dst; +#endif }; #endif /* __LINUX_SMP_TYPES_H */ diff --git a/kernel/smp.c b/kernel/smp.c index d0ae8eb..a47382d 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -375,6 +375,7 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info, csd->func = func; csd->info = info; + csd->dst = cpu; err = generic_exec_single(cpu, csd); @@ -540,6 +541,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask, csd->flags |= CSD_TYPE_SYNC; csd->func = func; csd->info = info; + csd->dst = cpu; if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) __cpumask_set_cpu(cpu, cfd->cpumask_ipi); } -- 2.9.5
