smp: Warn on function calls from softirq context (19dbdcb8) · Commits · 戴 / test

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

kernel/smp.c

+16 −0

Original line number	Diff line number	Diff line
		@@ -291,6 +291,14 @@ 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);
		@@ -416,6 +424,14 @@ 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)

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