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| author | Peter Zijlstra <peterz@infradead.org> | 2014-09-24 10:18:53 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-10-28 10:56:30 +0100 |
| commit | 3c9b2c3d64a49f264422d7743599cf7f6535972d (patch) | |
| tree | 72e5230f01883c626c4d9415b7c53f9cbc9f6365 /kernel/module.c | |
| parent | 7d4d26966e0b6443c78123a8a8b602e8eaf67694 (diff) | |
| download | linux-3c9b2c3d64a49f264422d7743599cf7f6535972d.tar.gz linux-3c9b2c3d64a49f264422d7743599cf7f6535972d.tar.bz2 linux-3c9b2c3d64a49f264422d7743599cf7f6535972d.zip | |
sched, modules: Fix nested sleep in add_unformed_module()
This is a genuine bug in add_unformed_module(), we cannot use blocking
primitives inside a wait loop.
So rewrite the wait_event_interruptible() usage to use the fresh
wait_woken() stuff.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: ilya.dryomov@inktank.com
Cc: umgwanakikbuti@gmail.com
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: oleg@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: http://lkml.kernel.org/r/20140924082242.458562904@infradead.org
[ So this is probably complex to backport and the race wasn't reported AFAIK,
so not marked for -stable. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/module.c')
| -rw-r--r-- | kernel/module.c | 30 |
1 files changed, 28 insertions, 2 deletions
diff --git a/kernel/module.c b/kernel/module.c index 88cec1ddb1e3..e52a8739361a 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3097,6 +3097,32 @@ 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(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. @@ -3116,8 +3142,8 @@ again: || 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; |