bad: scheduling while atomic! (Part Deux)
Sigh. Another MTD deadlock, and cause of scheduling badness on UP preempt.
David, I think MTD needs an audit to ensure that no further cases exist.
static void cfi_intelext_sync (struct mtd_info *mtd)
{
for (i=0; !ret && i<cfi->numchips; i++) {
chip = &cfi->chips[i];
spin_lock(chip->mutex);
ret = get_chip(map, chip, chip->start, FL_SYNCING);
...
}
/* Unlock the chips again */
for (i--; i >=0; i--) {
chip = &cfi->chips[i];
spin_lock(chip->mutex);
...
spin_unlock(chip->mutex);
}
}Signature · 2 lines
Russell King ([email protected]) The developer of ARM Linux http://www.arm.linux.org.uk/personal/aboutme.html
Quoted 4 lines · Russell King
Sigh. Another MTD deadlock, and cause of scheduling badness on UP preempt.
David, I think MTD needs an audit to ensure that no further cases exist.
Could this be done with smatch plus some perl? Being a lazy bastard, I like the idea of letting the machines do the boring repetetive job.
Quoted 12 lines
static void
cfi_intelext_sync(structmtd_info*mtd){ for (i=0; !ret && i<cfi->numchips; i++) { chip = &cfi->chips[i]; spin_lock(chip->mutex); ret = get_chip(map, chip, chip->start, FL_SYNCING); ... } /* Unlock the chips again */
Quoted 8 lines
for (i--; i >=0; i--) {
chip = &cfi->chips[i];
spin_lock(chip->mutex);
...
spin_unlock(chip->mutex);
}
}Mindless guess of a fix part 1 & 2 below.
As an anecdote, the stupid copy of cmdset_0001, cmdset_0020, did it right. Interesting.
Jörn
Signature · 40 lines
Courage is not the absence of fear, but rather the judgement that
something else is more important than fear.
-- Ambrose Redmoon
--- linux-2.5.71/drivers/mtd/mtd_blkdevs.c~mtd_spinlocks 2003-06-15 16:05:05.000000000 +0200
+++ linux-2.5.71/drivers/mtd/mtd_blkdevs.c 2003-06-15 16:19:43.000000000 +0200
@@ -93,14 +93,13 @@
recalc_sigpending();
spin_unlock_irq(¤t->sighand->siglock);
+ spin_lock_irq(rq->queue_lock);
while (!tr->blkcore_priv->exiting) {
struct request *req;
struct mtd_blktrans_dev *dev;
int res = 0;
DECLARE_WAITQUEUE(wait, current);
- spin_lock_irq(rq->queue_lock);
-
req = elv_next_request(rq);
if (!req) {
@@ -112,6 +111,7 @@
schedule();
remove_wait_queue(&tr->blkcore_priv->thread_wq, &wait);
+ spin_lock_irq(rq->queue_lock);
continue;
}
--- linux-2.5.71/drivers/mtd/chips/cfi_cmdset_0001.c~mtd_spinlocks 2003-06-15 16:05:03.000000000 +0200
+++ linux-2.5.71/drivers/mtd/chips/cfi_cmdset_0001.c 2003-06-15 17:33:43.000000000 +0200
@@ -1423,6 +1423,7 @@
* with the chip now anyway.
*/
}
+ spin_unlock(chip->mutex);
}
/* Unlock the chips again */