From 43057146932997ca54a2326cfd6abe9fe1ec5a9f Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Mon, 13 Jan 2014 19:37:54 -0500 Subject: [PATCH] dm sysfs: fix a module unload race commit 2995fa78e423d7193f3b57835f6c1c75006a0315 upstream. This reverts commit be35f48610 ("dm: wait until embedded kobject is released before destroying a device") and provides an improved fix. The kobject release code that calls the completion must be placed in a non-module file, otherwise there is a module unload race (if the process calling dm_kobject_release is preempted and the DM module unloaded after the completion is triggered, but before dm_kobject_release returns). To fix this race, this patch moves the completion code to dm-builtin.c which is always compiled directly into the kernel if BLK_DEV_DM is selected. The patch introduces a new dm_kobject_holder structure, its purpose is to keep the completion and kobject in one place, so that it can be accessed from non-module code without the need to export the layout of struct mapped_device to that code. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer [bwh: Backported to 3.2: - Adjust context - Remove paranoid check of container_of() result in dm_get_from_kobject(), which would now be incorrect - Include in dm-builtin.c, included indirectly upstream] Signed-off-by: Ben Hutchings --- Reading git-format-patch failed