Patch-mainline: v5.10-rc1

Git-commit: e48c15b796d412ede883bb2ef7779b2a142f7962

References: bsc#1180846

From: "Paul E. McKenney" <paulmck@kernel.org>

Date: Mon, 29 Jun 2020 17:21:32 -0700

Subject: [PATCH] smp: Add source and destination CPUs to __call_single_data

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.

[ paulmck: Apply Boqun Feng feedback on 32-bit builds. ]

Link: https://lore.kernel.org/lkml/20200615164048.GC2531@hirez.programming.kicks-ass.net/

Cc: Peter Zijlstra <peterz@infradead.org>

Cc: Ingo Molnar <mingo@kernel.org>

Cc: Thomas Gleixner <tglx@linutronix.de>

Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

Cc: Frederic Weisbecker <frederic@kernel.org>

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

Signed-off-by: Juergen Gross <jgross@suse.com>

---

 include/linux/smp.h       | 3 +++

 kernel/smp.c              | 6 ++++++

 2 files changed, 9 insertions(+)

diff --git a/include/linux/smp.h b/include/linux/smp.h

index 80d557ef8a11..9f13966d3d92 100644

--- a/include/linux/smp.h

+++ b/include/linux/smp.h

@@ -20,6 +20,9 @@ struct __call_single_data {

 	smp_call_func_t func;

 	void *info;

 	unsigned int flags;

+#ifdef CONFIG_64BIT

+	u16 src, dst;

+#endif

 };

 /* Use __aligned() to avoid to use 2 cache lines for 1 csd */

diff --git a/kernel/smp.c b/kernel/smp.c

index d0ae8eb6bf8b..865a876f83ce 100644

--- a/kernel/smp.c

+++ b/kernel/smp.c

@@ -164,6 +164,9 @@ int generic_exec_single(int cpu, call_single_data_t *csd,

 	csd->func = func;

 	csd->info = info;

+#ifdef CONFIG_64BIT

+	csd->dst = cpu;

+#endif

 	/*

 	 * The list addition should be visible before sending the IPI

@@ -470,6 +473,9 @@ static void smp_call_function_many(const struct cpumask *mask,

 			csd->flags |= CSD_FLAG_SYNCHRONOUS;

 		csd->func = func;

 		csd->info = info;

+#ifdef CONFIG_64BIT

+		csd->dst = cpu;

+#endif

 		if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))

 			__cpumask_set_cpu(cpu, cfd->cpumask_ipi);

 	}

-- 

2.26.2