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authorPeter Zijlstra <peterz@infradead.org>2015-02-11 15:01:13 +1030
committerRusty Russell <rusty@rustcorp.com.au>2015-02-11 15:02:04 +1030
commit9cc019b8c94fa59e02fd82f15f7b7d689e35c190 (patch)
tree0d6775b29012dd6a2df95cb16bd190faffd44780 /kernel
parentd64810f56147b53e92228c31442e925576314aa2 (diff)
downloadlinux-9cc019b8c94fa59e02fd82f15f7b7d689e35c190.tar.bz2
module: Replace over-engineered nested sleep
Since the introduction of the nested sleep warning; we've established that the occasional sleep inside a wait_event() is fine. wait_event() loops are invariant wrt. spurious wakeups, and the occasional sleep has a similar effect on them. As long as its occasional its harmless. Therefore replace the 'correct' but verbose wait_woken() thing with a simple annotation to shut up the warning. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/module.c36
1 files changed, 8 insertions, 28 deletions
diff --git a/kernel/module.c b/kernel/module.c
index d7a92682fba3..82dc1f899e6d 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2984,6 +2984,12 @@ static bool finished_loading(const char *name)
struct module *mod;
bool ret;
+ /*
+ * The module_mutex should not be a heavily contended lock;
+ * if we get the occasional sleep here, we'll go an extra iteration
+ * in the wait_event_interruptible(), which is harmless.
+ */
+ sched_annotate_sleep();
mutex_lock(&module_mutex);
mod = find_module_all(name, strlen(name), true);
ret = !mod || mod->state == MODULE_STATE_LIVE
@@ -3126,32 +3132,6 @@ 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(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.
@@ -3171,8 +3151,8 @@ again:
|| old->state == MODULE_STATE_UNFORMED) {
/* Wait in case it fails to load. */
mutex_unlock(&module_mutex);
-
- err = wait_finished_loading(mod);
+ err = wait_event_interruptible(module_wq,
+ finished_loading(mod->name));
if (err)
goto out_unlocked;
goto again;