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Gitweb: http://git.kernel.org/linus/d6de2c80e9d758d2e36c21699117db6178c0f517
Commit: d6de2c80e9d758d2e36c21699117db6178c0f517
Parent: 7933a3cfba017330ebb25f9820cb25ec9cdd67cc
Author: Linus Torvalds <torvalds@linux-foundation.org>
AuthorDate: Fri Apr 10 12:17:41 2009 -0700
Committer: Linus Torvalds <torvalds@linux-foundation.org>
CommitDate: Sat Apr 11 12:44:49 2009 -0700
async: Fix module loading async-work regression
Several drivers use asynchronous work to do device discovery, and we
synchronize with them in the compiled-in case before we actually try to
mount root filesystems etc.
However, when compiled as modules, that synchronization is missing - the
module loading completes, but the driver hasn't actually finished
probing for devices, and that means that any user mode that expects to
use the devices after the 'insmod' is now potentially broken.
We already saw one case of a similar issue in the ACPI battery code,
where the kernel itself expected the module to be all done, and unmapped
the init memory - but the async device discovery was still running.
That got hacked around by just removing the "__init" (see commit
5d38258ec026921a7b266f4047ebeaa75db358e5 "ACPI battery: fix async boot
oops"), but the real fix is to just make the module loading wait for all
async work to be completed.
It will slow down module loading, but since common devices should be
built in anyway, and since the bug is really annoying and hard to handle
from user space (and caused several S3 resume regressions), the simple
fix to wait is the right one.
This fixes at least
http://bugzilla.kernel.org/show_bug.cgi?id=13063
but probably a few other bugzilla entries too (12936, for example), and
is confirmed to fix Rafael's storage driver breakage after resume bug
report (no bugzilla entry).
We should also be able to now revert that ACPI battery fix.
Reported-and-tested-by: Rafael J. Wysocki <rjw@suse.com>
Tested-by: Heinz Diehl <htd@fancy-poultry.org>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/module.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c
index 05f014e..e797812 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2388,6 +2388,9 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_LIVE, mod);
+ /* We need to finish all async code before the module init sequence is done */
+ async_synchronize_full();
+
mutex_lock(&module_mutex);
/* Drop initial reference. */
module_put(mod);
--
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