The branch, master has been updated
via 00513da g_lock: Simplify g_lock_trylock
via 6b3cc79 g_lock: Avoid a double call to serverid_exist
from a98f09a selftest: Load time_audit and full_audit modules for all
tests
https://git.samba.org/?p=samba.git;a=shortlog;h=master
- Log -----------------------------------------------------------------
commit 00513daf78eb29996c81ca4d3be9e71a8e872829
Author: Volker Lendecke <v...@samba.org>
Date: Mon Aug 13 15:07:06 2018 +0200
g_lock: Simplify g_lock_trylock
While chasing a bug in g_lock (not in master) I saw some opportunity to
simplify g_lock_trylock a bit. This is array handling, and array
handling is just extremely error-prone. This *might* be a little less
efficient or large numbers of READ locks, but this remains to be
seen. For now, simplify the code.
First, we make two passes now: One to remove ourselves, and the other
one to search for conflicts. Mixing up both made it pretty hard for me
to follow the code.
Second, I've removed the _mylock and mylock pointer/struct logic and
replaced it with the "mylock.pid.pid != 0 ? &mylock : NULL" when calling
g_lock_store. To me, this focuses the logic whether to add ourselves in
one place instead of spreading it around in the whole routine.
Signed-off-by: Volker Lendecke <v...@samba.org>
Reviewed-by: Jeremy Allison <j...@samba.org>
Autobuild-User(master): Volker Lendecke <v...@samba.org>
Autobuild-Date(master): Tue Aug 14 11:42:10 CEST 2018 on sn-devel-144
commit 6b3cc7916b81e001b886b9c632babe345ca21d76
Author: Volker Lendecke <v...@samba.org>
Date: Mon Aug 13 14:12:47 2018 +0200
g_lock: Avoid a double call to serverid_exist
If we try to G_LOCK_READ while a G_LOCK_WRITE is active, we do the
serverid_exists call twice. Avoid that.
Signed-off-by: Volker Lendecke <v...@samba.org>
Reviewed-by: Jeremy Allison <j...@samba.org>
-----------------------------------------------------------------------
Summary of changes:
source3/lib/g_lock.c | 56 ++++++++++++++++++++++++++++++++++------------------
1 file changed, 37 insertions(+), 19 deletions(-)
Changeset truncated at 500 lines:
diff --git a/source3/lib/g_lock.c b/source3/lib/g_lock.c
index bffbd6b..de24b6c 100644
--- a/source3/lib/g_lock.c
+++ b/source3/lib/g_lock.c
@@ -200,8 +200,7 @@ static NTSTATUS g_lock_trylock(struct db_record *rec,
struct server_id self,
TDB_DATA data;
size_t i;
struct g_lock lck;
- struct g_lock_rec _mylock;
- struct g_lock_rec *mylock = NULL;
+ struct g_lock_rec mylock = {0};
NTSTATUS status;
bool modified = false;
bool ok;
@@ -226,15 +225,20 @@ static NTSTATUS g_lock_trylock(struct db_record *rec,
struct server_id self,
g_lock_get_rec(&lck, i, &check_rec);
- if (!serverid_exists(&check_rec.pid)) {
+ if ((check_rec.lock_type == G_LOCK_READ) &&
+ !serverid_exists(&check_rec.pid)) {
g_lock_rec_del(&lck, i);
modified = true;
}
}
- i = 0;
+ /*
+ * For the lock upgrade/downgrade case, remove ourselves from
+ * the list. We re-add ourselves later after we checked the
+ * other entries for conflict.
+ */
- while (i < lck.num_recs) {
+ for (i=0; i<lck.num_recs; i++) {
struct g_lock_rec lock;
g_lock_get_rec(&lck, i, &lock);
@@ -244,20 +248,26 @@ static NTSTATUS g_lock_trylock(struct db_record *rec,
struct server_id self,
status = NT_STATUS_WAS_LOCKED;
goto done;
}
- if (mylock != NULL) {
- status = NT_STATUS_INTERNAL_DB_CORRUPTION;
- goto done;
- }
- _mylock = lock;
- mylock = &_mylock;
- /*
- * Remove "our" lock entry. Re-add it later
- * with our new lock type.
- */
+
+ mylock = lock;
g_lock_rec_del(&lck, i);
modified = true;
- continue;
+ break;
}
+ }
+
+ /*
+ * Check for conflicts with everybody else. Not a for-loop
+ * because we remove stale entries in the meantime,
+ * decrementing lck.num_recs.
+ */
+
+ i = 0;
+
+ while (i < lck.num_recs) {
+ struct g_lock_rec lock;
+
+ g_lock_get_rec(&lck, i, &lock);
if (g_lock_conflicts(type, lock.lock_type)) {
struct server_id pid = lock.pid;
@@ -287,18 +297,26 @@ static NTSTATUS g_lock_trylock(struct db_record *rec,
struct server_id self,
modified = true;
- _mylock = (struct g_lock_rec) {
+ mylock = (struct g_lock_rec) {
.pid = self,
.lock_type = type
};
- mylock = &_mylock;
status = NT_STATUS_OK;
done:
if (modified) {
NTSTATUS store_status;
- store_status = g_lock_store(rec, &lck, mylock);
+ /*
+ * (Re-)add ourselves if needed via non-NULL
+ * g_lock_store argument
+ */
+
+ store_status = g_lock_store(
+ rec,
+ &lck,
+ mylock.pid.pid != 0 ? &mylock : NULL);
+
if (!NT_STATUS_IS_OK(store_status)) {
DBG_WARNING("g_lock_record_store failed: %s\n",
nt_errstr(store_status));
--
Samba Shared Repository
