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Commit 37a76bd4 authored by Arjan van de Ven's avatar Arjan van de Ven Committed by Linus Torvalds
Browse files

async: fix __lowest_in_progress() 



At 37000 feet somewhere near Greenland I woke up from a half-sleep with the
realisation that __lowest_in_progress() is buggy. After landing I checked
and there were indeed 2 problems with it; this patch fixes both:
* The order of the list checks was wrong
* The locking was not correct.

Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d32ad102

kernel/async.c

+16 −5
Original line number Diff line number Diff line
@@ -90,12 +90,12 @@ extern int initcall_debug; 
static async_cookie_t  __lowest_in_progress(struct list_head *running)

{

	struct async_entry *entry;

	if (!list_empty(&async_pending)) {

		entry = list_first_entry(&async_pending,

	if (!list_empty(running)) {

		entry = list_first_entry(running,

			struct async_entry, list);

		return entry->cookie;

	} else if (!list_empty(running)) {

		entry = list_first_entry(running,

	} else if (!list_empty(&async_pending)) {

		entry = list_first_entry(&async_pending,

			struct async_entry, list);

		return entry->cookie;

	} else {
@@ -104,6 +104,17 @@ static async_cookie_t __lowest_in_progress(struct list_head *running) 
	}



}



static async_cookie_t  lowest_in_progress(struct list_head *running)

{

	unsigned long flags;

	async_cookie_t ret;



	spin_lock_irqsave(&async_lock, flags);

	ret = __lowest_in_progress(running);

	spin_unlock_irqrestore(&async_lock, flags);

	return ret;

}

/*

 * pick the first pending entry and run it

 */
@@ -229,7 +240,7 @@ void async_synchronize_cookie_special(async_cookie_t cookie, struct list_head *r 
		starttime = ktime_get();

	}



	wait_event(async_done, __lowest_in_progress(running) >= cookie);

	wait_event(async_done, lowest_in_progress(running) >= cookie);



	if (initcall_debug && system_state == SYSTEM_BOOTING) {

		endtime = ktime_get();