Messages in this thread Patch in this message | | | Date | Wed, 24 Sep 2014 10:18:53 +0200 | From | Peter Zijlstra <> | Subject | [PATCH 08/11] module: Fix nested sleep |
| |
A genuine bug, we cannot use blocking primitives inside a wait loop.
So rewrite the wait_event_interruptible() usage to use the fresh wait_woken() stuff.
Cc: Rusty Russell <rusty@rustcorp.com.au> Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- kernel/module.c | 30 ++++++++++++++++++++++++++++-- 1 file changed, 28 insertions(+), 2 deletions(-)
--- a/kernel/module.c +++ b/kernel/module.c @@ -3095,6 +3095,32 @@ static int may_init_module(void) } /* + * Can't use wait_event_interruptible() because our condition + * 'finished_loading()' contains a blocking primitive itself (mutex_lock). + */ +static int wait_finished_loading(struct module *mod) +{ + DEFINE_WAIT_FUNC(wait, woken_wake_function); + int ret = 0; + + add_wait_queue(&module_wq, &wait); + for (;;) { + if (finished_loading(mod->name)) + break; + + if (signal_pending_state(TASK_INTERRUPTIBLE, current)) { + ret = -ERESTARTSYS; + break; + } + + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); + } + remove_wait_queue(&module_wq, &wait); + + return ret; +} + +/* * We try to place it in the list now to make sure it's unique before * we dedicate too many resources. In particular, temporary percpu * memory exhaustion. @@ -3114,8 +3140,8 @@ static int add_unformed_module(struct mo || old->state == MODULE_STATE_UNFORMED) { /* Wait in case it fails to load. */ mutex_unlock(&module_mutex); - err = wait_event_interruptible(module_wq, - finished_loading(mod->name)); + + err = wait_finished_loading(mod); if (err) goto out_unlocked; goto again;
| |