rmmod/3080 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
(proc_subdir_lock){--..}, at: [<c04a33b0>] remove_proc_entry+0x40/0x191
and this task is already holding:
(ide_lock){++..}, at: [<c05651a2>] ide_unregister_subdriver+0x39/0xc8
which would create a new lock dependency:
(ide_lock){++..} -> (proc_subdir_lock){--..}
but this new dependency connects a hard-irq-safe lock:
(ide_lock){++..}
... which became hard-irq-safe at:
[<c043c458>] lock_acquire+0x4b/0x6b
[<c06129d7>] _spin_lock_irqsave+0x22/0x32
[<c0567870>] ide_intr+0x17/0x1a9
[<c044eb31>] handle_IRQ_event+0x20/0x4d
[<c044ebf2>] __do_IRQ+0x94/0xef
[<c0406771>] do_IRQ+0x9e/0xbd
to a hard-irq-unsafe lock:
(proc_subdir_lock){--..}
... which became hard-irq-unsafe at:
... [<c043c458>] lock_acquire+0x4b/0x6b
[<c06126ab>] _spin_lock+0x19/0x28
[<c04a32f2>] xlate_proc_name+0x1b/0x99
[<c04a3547>] proc_create+0x46/0xdf
[<c04a3642>] create_proc_entry+0x62/0xa5
[<c07c1972>] proc_misc_init+0x1c/0x1d2
[<c07c1844>] proc_root_init+0x4c/0xe9
[<c07ad703>] start_kernel+0x294/0x3b3
[<00000000>] 0x0
Move ide_remove_proc_entries() out from under ide_lock; there is nothing
that indicates that this is needed.
In specific, the call to ide_add_proc_entries() is unprotected, and there
is nothing else in the file using the respective ->proc fields. Also the
lock order around destroy_proc_ide_interface() suggests this.
Signed-off-by: Peter Zijlstra <[email protected]>
---
drivers/ide/ide.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
Index: linux-2.6/drivers/ide/ide.c
===================================================================
--- linux-2.6.orig/drivers/ide/ide.c
+++ linux-2.6/drivers/ide/ide.c
@@ -973,8 +973,8 @@ ide_settings_t *ide_find_setting_by_name
* @drive: drive
*
* Automatically remove all the driver specific settings for this
- * drive. This function may sleep and must not be called from IRQ
- * context. The caller must hold ide_setting_sem.
+ * drive. This function may not be called from IRQ context. The
+ * caller must hold ide_setting_sem.
*/
static void auto_remove_settings (ide_drive_t *drive)
@@ -1874,11 +1874,22 @@ void ide_unregister_subdriver(ide_drive_
{
unsigned long flags;
- down(&ide_setting_sem);
- spin_lock_irqsave(&ide_lock, flags);
#ifdef CONFIG_PROC_FS
ide_remove_proc_entries(drive->proc, driver->proc);
#endif
+ down(&ide_setting_sem);
+ spin_lock_irqsave(&ide_lock, flags);
+ /*
+ * ide_setting_sem protects the settings list
+ * ide_lock protects the use of settings
+ *
+ * so we need to hold both, ide_settings_sem because we want to
+ * modify the settings list, and ide_lock because we cannot take
+ * a setting out that is being used.
+ *
+ * OTOH both ide_{read,write}_setting are only ever used under
+ * ide_setting_sem.
+ */
auto_remove_settings(drive);
spin_unlock_irqrestore(&ide_lock, flags);
up(&ide_setting_sem);
-
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