From 12997d1a999cd1b22e21a238c96780f2a55e4e13 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Mon, 18 Nov 2013 11:00:29 -0700 Subject: [PATCH] Revert "workqueue: allow work_on_cpu() to be called recursively" This reverts commit c2fda509667b0fda4372a237f5a59ea4570b1627. c2fda509667b removed lockdep annotation from work_on_cpu() to work around the PCI path that calls work_on_cpu() from within a work_on_cpu() work item (PF driver .probe() method -> pci_enable_sriov() -> add VFs -> VF driver .probe method). 961da7fb6b22 ("PCI: Avoid unnecessary CPU switch when calling driver .probe() method) avoids that recursive work_on_cpu() use in a different way, so this revert restores the work_on_cpu() lockdep annotation. Signed-off-by: Bjorn Helgaas Acked-by: Tejun Heo --- kernel/workqueue.c | 32 ++++++++++---------------------- 1 file changed, 10 insertions(+), 22 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 987293d03ebc..5690b8eabfbc 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -2840,19 +2840,6 @@ static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) return false; } -static bool __flush_work(struct work_struct *work) -{ - struct wq_barrier barr; - - if (start_flush_work(work, &barr)) { - wait_for_completion(&barr.done); - destroy_work_on_stack(&barr.work); - return true; - } else { - return false; - } -} - /** * flush_work - wait for a work to finish executing the last queueing instance * @work: the work to flush @@ -2866,10 +2853,18 @@ static bool __flush_work(struct work_struct *work) */ bool flush_work(struct work_struct *work) { + struct wq_barrier barr; + lock_map_acquire(&work->lockdep_map); lock_map_release(&work->lockdep_map); - return __flush_work(work); + if (start_flush_work(work, &barr)) { + wait_for_completion(&barr.done); + destroy_work_on_stack(&barr.work); + return true; + } else { + return false; + } } EXPORT_SYMBOL_GPL(flush_work); @@ -4814,14 +4809,7 @@ long work_on_cpu(int cpu, long (*fn)(void *), void *arg) INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); schedule_work_on(cpu, &wfc.work); - - /* - * The work item is on-stack and can't lead to deadlock through - * flushing. Use __flush_work() to avoid spurious lockdep warnings - * when work_on_cpu()s are nested. - */ - __flush_work(&wfc.work); - + flush_work(&wfc.work); return wfc.ret; } EXPORT_SYMBOL_GPL(work_on_cpu);