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Fix tll state bug

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When a lock has read-serialized and read-only locks, releasing the read-
serialized lock would not set the state to read-only when no other locks
were pending.
This commit is contained in:
Thomas Veerman 2012-01-11 10:20:44 +00:00
parent af6c39fb9b
commit a4d01f8a83
1 changed files with 11 additions and 2 deletions
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11
servers/avfs/tll.c
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@ -93,6 +93,7 @@ PUBLIC void tll_downgrade(tll_t *tllp)
case TLL_READSER: case TLL_READSER:
/* If nothing is queued on write-only, but there is a pending lock /* If nothing is queued on write-only, but there is a pending lock
* requesting read-serialized, grant it and keep the lock type. */ * requesting read-serialized, grant it and keep the lock type. */
if (tllp->t_write == NULL && tllp->t_serial != NULL) { if (tllp->t_write == NULL && tllp->t_serial != NULL) {
tllp->t_owner = tllp->t_serial; tllp->t_owner = tllp->t_serial;
tllp->t_serial = tllp->t_serial->w_next; /* Remove head */ tllp->t_serial = tllp->t_serial->w_next; /* Remove head */
@ -108,6 +109,9 @@ PUBLIC void tll_downgrade(tll_t *tllp)
break; break;
default: panic("VFS: Incorrect lock state"); default: panic("VFS: Incorrect lock state");
} }
if (tllp->t_current != TLL_WRITE && tllp->t_current != TLL_READSER)
assert(tllp->t_owner == NULL);
} }
PUBLIC void tll_init(tll_t *tllp) PUBLIC void tll_init(tll_t *tllp)
@ -233,6 +237,7 @@ PUBLIC int tll_unlock(tll_t *tllp)
/* This unlock must have been done by a read-only lock */ /* This unlock must have been done by a read-only lock */
tllp->t_readonly--; tllp->t_readonly--;
assert(tllp->t_readonly >= 0); assert(tllp->t_readonly >= 0);
assert(tllp->t_current == TLL_READ || tllp->t_current == TLL_READSER);
/* If a read-serialized lock is trying to upgrade and there are no more /* If a read-serialized lock is trying to upgrade and there are no more
* read-only locks, the lock can now be upgraded to write-only */ * read-only locks, the lock can now be upgraded to write-only */
@ -269,8 +274,12 @@ PUBLIC int tll_unlock(tll_t *tllp)
} }
/* If no one is using this lock, mark it as not in use */ /* If no one is using this lock, mark it as not in use */
if (tllp->t_owner == NULL && tllp->t_readonly == 0) if (tllp->t_owner == NULL) {
if (tllp->t_readonly == 0)
tllp->t_current = TLL_NONE; tllp->t_current = TLL_NONE;
else
tllp->t_current = TLL_READ;
}
if (tllp->t_current == TLL_NONE || tllp->t_current == TLL_READ) { if (tllp->t_current == TLL_NONE || tllp->t_current == TLL_READ) {
if (!signal_owner) { if (!signal_owner) {