Commit-ID: 19dbdcb8039cff16669a05136a29180778d16d0a Gitweb: https://git.kernel.org/tip/19dbdcb8039cff16669a05136a29180778d16d0a Author: Peter Zijlstra <pet...@infradead.org> AuthorDate: Thu, 18 Jul 2019 11:20:09 +0200 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Sat, 20 Jul 2019 11:27:16 +0200
smp: Warn on function calls from softirq context 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 <lufe...@163.com> Signed-off-by: Peter Zijlstra <pet...@infradead.org> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Link: https://lkml.kernel.org/r/20190718160601.gp3...@hirez.programming.kicks-ass.net --- kernel/smp.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/kernel/smp.c b/kernel/smp.c index 616d4d114847..7dbcb402c2fc 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -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)
