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authorLinus Torvalds <torvalds@linux-foundation.org>2009-04-10 12:17:41 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-11 12:44:49 -0700
commitd6de2c80e9d758d2e36c21699117db6178c0f517 (patch)
tree8f581ff1b8bce93fdeac949e0549c791d1ce52f9 /kernel
parent7933a3cfba017330ebb25f9820cb25ec9cdd67cc (diff)
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/module.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/module.c b/kernel/module.c
index 05f014efa32..e797812a4d9 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);