diff mbox series

[4.19] smp: Warn on function calls from softirq context

Message ID 20210219064526.69529-1-simon.wy@alibaba-inc.com
State New
Headers show
Series [4.19] smp: Warn on function calls from softirq context | expand

Commit Message

Wen Yang Feb. 19, 2021, 6:45 a.m. UTC 
From: Peter Zijlstra <peterz@infradead.org>

commit 19dbdcb8039cff16669a05136a29180778d16d0a upstream.

It's clearly documented that smp function calls cannot be invoked from
softirq handling context. Unfortunately nothing enforces that or emits a
warning.

A single function call can be invoked from softirq context only via
smp_call_function_single_async().

The only legit context is task context, so add a warning to that effect.

Reported-by: luferry <luferry@163.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190718160601.GP3402@hirez.programming.kicks-ass.net
Cc: stable <stable@vger.kernel.org> # 4.19.x
Signed-off-by: Wen Yang <simon.wy@alibaba-inc.com>
---
 kernel/smp.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
diff mbox series

Patch

diff --git a/kernel/smp.c b/kernel/smp.c
index 084c8b3..9afcbb4 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -290,6 +290,14 @@  int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
 	WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
 		     && !oops_in_progress);
 
+	/*
+	 * When @wait we can deadlock when we interrupt between llist_add() and
+	 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
+	 * csd_lock() on because the interrupt context uses the same csd
+	 * storage.
+	 */
+	WARN_ON_ONCE(!in_task());
+
 	csd = &csd_stack;
 	if (!wait) {
 		csd = this_cpu_ptr(&csd_data);
@@ -415,6 +423,14 @@  void smp_call_function_many(const struct cpumask *mask,
 	WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
 		     && !oops_in_progress && !early_boot_irqs_disabled);
 
+	/*
+	 * When @wait we can deadlock when we interrupt between llist_add() and
+	 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
+	 * csd_lock() on because the interrupt context uses the same csd
+	 * storage.
+	 */
+	WARN_ON_ONCE(!in_task());
+
 	/* Try to fastpath.  So, what's a CPU they want? Ignoring this one. */
 	cpu = cpumask_first_and(mask, cpu_online_mask);
 	if (cpu == this_cpu)