smp: Allocate smp_call_on_cpu() workqueue on stack too

The SMP IPI struct descriptor is allocated on the stack except for the
workqueue and lockdep complains:

  INFO: trying to register non-static key.
  the code is fine but needs lockdep annotation.
  turning off the locking correctness validator.
  CPU: 0 PID: 110 Comm: kworker/0:1 Not tainted 4.8.0-rc5+ #14
  Hardware name: Dell Inc. Precision T3600/0PTTT9, BIOS A13 05/11/2014
  Workqueue: events smp_call_on_cpu_callback
  ...
  Call Trace:
    dump_stack
    register_lock_class
    ? __lock_acquire
    __lock_acquire
    ? __lock_acquire
    lock_acquire
    ? process_one_work
    process_one_work
    ? process_one_work
    worker_thread
    ? process_one_work
    ? process_one_work
    kthread
    ? kthread_create_on_node
    ret_from_fork

So allocate it on the stack too.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[ Test and write commit message. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160911084323.jhtnpb4b37t5tlno@pd.tnic
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/smp.c b/kernel/smp.c
index f4f6137..bba3b20 100644 (file)
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -759,13 +759,14 @@ static void smp_call_on_cpu_callback(struct work_struct *work)
 int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
 {
        struct smp_call_on_cpu_struct sscs = {
-               .work = __WORK_INITIALIZER(sscs.work, smp_call_on_cpu_callback),
                .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
                .func = func,
                .data = par,
                .cpu  = phys ? cpu : -1,
        };
 
+       INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);
+
        if (cpu >= nr_cpu_ids || !cpu_online(cpu))
                return -ENXIO;