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async: fix __lowest_in_progress()

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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: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Arjan van de Ven 2009-01-11 15:35:01 +00:00 committed by Linus Torvalds
parent d32ad102c6
commit 37a76bd4f1
1 changed files with 16 additions and 5 deletions
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21
kernel/async.c
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@ -90,12 +90,12 @@ extern int initcall_debug;
static async_cookie_t __lowest_in_progress(struct list_head *running) static async_cookie_t __lowest_in_progress(struct list_head *running)
{ {
struct async_entry *entry; struct async_entry *entry;
if (!list_empty(&async_pending)) { if (!list_empty(running)) {
entry = list_first_entry(&async_pending, entry = list_first_entry(running,
struct async_entry, list); struct async_entry, list);
return entry->cookie; return entry->cookie;
} else if (!list_empty(running)) { } else if (!list_empty(&async_pending)) {
entry = list_first_entry(running, entry = list_first_entry(&async_pending,
struct async_entry, list); struct async_entry, list);
return entry->cookie; return entry->cookie;
} else { } 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 * 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(); 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) { if (initcall_debug && system_state == SYSTEM_BOOTING) {
endtime = ktime_get(); endtime = ktime_get();