diff options
Diffstat (limited to 'src/lock/lock_deadlock.c')
| -rw-r--r-- | src/lock/lock_deadlock.c | 47 |
1 files changed, 27 insertions, 20 deletions
diff --git a/src/lock/lock_deadlock.c b/src/lock/lock_deadlock.c index 3c00d7f1..79086687 100644 --- a/src/lock/lock_deadlock.c +++ b/src/lock/lock_deadlock.c @@ -1,7 +1,7 @@ /*- * See the file LICENSE for redistribution information. * - * Copyright (c) 1996, 2012 Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 1996, 2015 Oracle and/or its affiliates. All rights reserved. * * $Id$ */ @@ -683,38 +683,45 @@ again: memset(bitmap, 0, count * sizeof(u_int32_t) * nentries); /* * Now for each locker, record its last lock and set abort status. * We need to look at the heldby list carefully. We have the LOCKERS - * locked so they cannot go away. The lock at the head of the - * list can be removed by locking the object it points at. - * Since lock memory is not freed if we get a lock we can look - * at it safely but SH_LIST_FIRST is not atomic, so we check that - * the list has not gone empty during that macro. We check abort - * status after building the bit maps so that we will not detect - * a blocked transaction without noting that it is already aborting. + * locked so they cannot go away. The LOCK_SYSTEM_LOCK keeps things + * steady when the lock table is not partitioned. However, if there are + * multiple lock partitions then the head of the heldby list can be + * changed by another thread locking the object it points at. That + * thread will have OBJECT_LOCK()'d that lock's partition. We need to + * look at the lock entry in order to determine which partition to + * mutex_lock. Since lock structs are never really freed, once we get + * the pointer we can look at it safely. However SH_LIST_FIRST is not + * atomic, so we first fetch the pointer and then check that the list + * was not empty during the fetch. This lets us at least mutex_lock the + * partition of the lock. Afterwards, we retry if the lock is no longer + * the first for that locker -- it might have changed to something ELSE + * since then. We check abort status after building the bit maps so that + * we will not pick a blocked transaction without noting that it is + * already aborting. */ for (id = 0; id < count; id++) { if (!id_array[id].valid) continue; - if ((ret = __lock_getlocker_int(lt, - id_array[id].id, 0, &lockerp)) != 0 || lockerp == NULL) + if ((ret = __lock_getlocker_int(lt, id_array[id].id, + 0, NULL, &lockerp)) != 0 || lockerp == NULL) continue; /* - * If this is a master transaction, try to - * find one of its children's locks first, - * as they are probably more recent. + * If this is a master transaction, try to find one of its + * children's locks first, as they are probably more recent. */ child = SH_LIST_FIRST(&lockerp->child_locker, __db_locker); if (child != NULL) { do { -c_retry: lp = SH_LIST_FIRST(&child->heldby, __db_lock); - if (SH_LIST_EMPTY(&child->heldby) || lp == NULL) +c_retry: lp = SH_LIST_FIRSTP(&child->heldby, __db_lock); + if (__SH_LIST_WAS_EMPTY(&child->heldby, lp)) goto c_next; if (F_ISSET(child, DB_LOCKER_INABORT)) id_array[id].in_abort = 1; ndx = lp->indx; OBJECT_LOCK_NDX(lt, region, ndx); - if (lp != SH_LIST_FIRST( + if (lp != SH_LIST_FIRSTP( &child->heldby, __db_lock) || ndx != lp->indx) { OBJECT_UNLOCK(lt, region, ndx); @@ -733,11 +740,11 @@ c_next: child = SH_LIST_NEXT( } while (child != NULL); } -l_retry: lp = SH_LIST_FIRST(&lockerp->heldby, __db_lock); - if (!SH_LIST_EMPTY(&lockerp->heldby) && lp != NULL) { +l_retry: lp = SH_LIST_FIRSTP(&lockerp->heldby, __db_lock); + if (!__SH_LIST_WAS_EMPTY(&lockerp->heldby, lp)) { ndx = lp->indx; OBJECT_LOCK_NDX(lt, region, ndx); - if (lp != SH_LIST_FIRST(&lockerp->heldby, __db_lock) || + if (lp != SH_LIST_FIRSTP(&lockerp->heldby, __db_lock) || lp->indx != ndx) { OBJECT_UNLOCK(lt, region, ndx); goto l_retry; @@ -869,7 +876,7 @@ __dd_abort(env, info, statusp) * detecting, return that. */ if ((ret = __lock_getlocker_int(lt, - info->last_locker_id, 0, &lockerp)) != 0) + info->last_locker_id, 0, NULL, &lockerp)) != 0) goto err; if (lockerp == NULL || F_ISSET(lockerp, DB_LOCKER_INABORT)) { *statusp = DB_ALREADY_ABORTED; |