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MINOR: fd: reorder fd_add_to_fd_list()

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The function was cleaned up a bit from duplicated parts inherited from
the initial attempt at getting it to work. It's a bit smaller and cleaner
this way.
This commit is contained in:
Willy Tarreau 2018-02-05 17:52:24 +01:00
parent 3a8263f86b
commit 11559a7530
1 changed files with 18 additions and 29 deletions
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33
src/fd.c
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@ -191,50 +191,39 @@ redo_next:
if (!HA_ATOMIC_CAS(&fdtab[fd].cache.next, &next, -2))
goto redo_next;
__ha_barrier_store();
new = fd;
redo_last:
/* First, insert in the linked list */
last = list->last;
old = -1;
new = fd;
if (unlikely(last == -1)) {
/* list is empty, try to add ourselves alone so that list->last=fd */
fdtab[fd].cache.prev = last;
/* Make sure the "prev" store is visible before we update the last entry */
__ha_barrier_store();
if (unlikely(last == -1)) {
/* list is empty, try to add ourselves alone so that list->last=fd */
if (unlikely(!HA_ATOMIC_CAS(&list->last, &old, new)))
goto redo_last;
/* list->first was necessary -1, we're guaranteed to be alone here */
list->first = fd;
/* since we're alone at the end of the list and still locked(-2),
* we know noone tried to add past us. Mark the end of list.
*/
fdtab[fd].cache.next = -1;
goto done; /* We're done ! */
} else {
/* non-empty list, add past the tail */
do {
new = fd;
old = -1;
fdtab[fd].cache.prev = last;
__ha_barrier_store();
/* adding ourselves past the last element
* The CAS will only succeed if its next is -1,
* which means it's in the cache, and the last element.
*/
if (likely(HA_ATOMIC_CAS(&fdtab[last].cache.next, &old, new)))
break;
if (unlikely(!HA_ATOMIC_CAS(&fdtab[last].cache.next, &old, new)))
goto redo_last;
} while (1);
}
/* Then, update the last entry */
list->last = fd;
}
__ha_barrier_store();
/* since we're alone at the end of the list and still locked(-2),
* we know noone tried to add past us. Mark the end of list.
*/
fdtab[fd].cache.next = -1;
__ha_barrier_store();
done: