[MTD] NAND: Reorganize chip locking
The code was wrong in several aspects. The locking order was
inconsistent, the device aquire code did not reset a variable
after a wakeup and the wakeup handling was not working for
applications where multiple chips are sharing a single
hardware controller.
When a hardware controller is available the locking is now
reduced to the hardware controller lock and the waitqueue is
moved to the hardware controller structure in order to avoid
a wake_up_all().
The problem was pointed out by Ben Dooks, who also found the
missing variable reset as main cause for his deadlock problem.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index f1db0bf..bbe0283 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -59,7 +59,7 @@
* The AG-AND chips have nice features for speed improvement,
* which are not supported yet. Read / program 4 pages in one go.
*
- * $Id: nand_base.c,v 1.143 2005/05/19 16:10:22 gleixner Exp $
+ * $Id: nand_base.c,v 1.145 2005/05/31 20:32:53 gleixner Exp $
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
@@ -167,17 +167,21 @@
/* De-select the NAND device */
this->select_chip(mtd, -1);
- /* Do we have a hardware controller ? */
+
if (this->controller) {
+ /* Release the controller and the chip */
spin_lock(&this->controller->lock);
this->controller->active = NULL;
+ this->state = FL_READY;
+ wake_up(&this->controller->wq);
spin_unlock(&this->controller->lock);
+ } else {
+ /* Release the chip */
+ spin_lock(&this->chip_lock);
+ this->state = FL_READY;
+ wake_up(&this->wq);
+ spin_unlock(&this->chip_lock);
}
- /* Release the chip */
- spin_lock (&this->chip_lock);
- this->state = FL_READY;
- wake_up (&this->wq);
- spin_unlock (&this->chip_lock);
}
/**
@@ -753,37 +757,34 @@
*/
static void nand_get_device (struct nand_chip *this, struct mtd_info *mtd, int new_state)
{
- struct nand_chip *active = this;
-
+ struct nand_chip *active;
+ spinlock_t *lock;
+ wait_queue_head_t *wq;
DECLARE_WAITQUEUE (wait, current);
- /*
- * Grab the lock and see if the device is available
- */
+ lock = (this->controller) ? &this->controller->lock : &this->chip_lock;
+ wq = (this->controller) ? &this->controller->wq : &this->wq;
retry:
+ active = this;
+ spin_lock(lock);
+
/* Hardware controller shared among independend devices */
if (this->controller) {
- spin_lock (&this->controller->lock);
if (this->controller->active)
active = this->controller->active;
else
this->controller->active = this;
- spin_unlock (&this->controller->lock);
}
-
- if (active == this) {
- spin_lock (&this->chip_lock);
- if (this->state == FL_READY) {
- this->state = new_state;
- spin_unlock (&this->chip_lock);
- return;
- }
- }
- set_current_state (TASK_UNINTERRUPTIBLE);
- add_wait_queue (&active->wq, &wait);
- spin_unlock (&active->chip_lock);
- schedule ();
- remove_wait_queue (&active->wq, &wait);
+ if (active == this && this->state == FL_READY) {
+ this->state = new_state;
+ spin_unlock(lock);
+ return;
+ }
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ add_wait_queue(wq, &wait);
+ spin_unlock(lock);
+ schedule();
+ remove_wait_queue(wq, &wait);
goto retry;
}