tdb2: check lock owner in tdb1 backend.
authorRusty Russell <rusty@rustcorp.com.au>
Wed, 31 Aug 2011 06:01:08 +0000 (15:31 +0930)
committerRusty Russell <rusty@rustcorp.com.au>
Wed, 31 Aug 2011 06:01:08 +0000 (15:31 +0930)
This reports errors if we fork() while holding a lock, or misuse a tdb
which we have dual-opened.

ccan/tdb2/lock.c
ccan/tdb2/private.h
ccan/tdb2/tdb1_lock.c

index 7d4311c8e568b8125d72d2e91ec3dd0c8b08d4b9..bf62d9719e90c60f795ecd8acbce34c99df212b4 100644 (file)
@@ -30,7 +30,7 @@
 #include <ccan/build_assert/build_assert.h>
 
 /* If we were threaded, we could wait for unlock, but we're not, so fail. */
-static enum TDB_ERROR owner_conflict(struct tdb_context *tdb, const char *call)
+enum TDB_ERROR owner_conflict(struct tdb_context *tdb, const char *call)
 {
        return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
                          "%s: lock owned by another tdb in this process.",
@@ -38,8 +38,7 @@ static enum TDB_ERROR owner_conflict(struct tdb_context *tdb, const char *call)
 }
 
 /* If we fork, we no longer really own locks. */
-static bool check_lock_pid(struct tdb_context *tdb,
-                          const char *call, bool log)
+bool check_lock_pid(struct tdb_context *tdb, const char *call, bool log)
 {
        /* No locks?  No problem! */
        if (tdb->file->allrecord_lock.count == 0
@@ -787,6 +786,11 @@ enum TDB_ERROR tdb_unlock_hashes(struct tdb_context *tdb,
                        return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
                                          "tdb_unlock_hashes RO allrecord!");
                }
+               if (tdb->file->allrecord_lock.owner != tdb) {
+                       return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
+                                         "tdb_unlock_hashes:"
+                                         " not locked by us!");
+               }
                return TDB_SUCCESS;
        }
 
@@ -817,6 +821,10 @@ enum TDB_ERROR tdb_lock_free_bucket(struct tdb_context *tdb, tdb_off_t b_off,
                if (!check_lock_pid(tdb, "tdb_lock_free_bucket", true))
                        return TDB_ERR_LOCK;
 
+               if (tdb->file->allrecord_lock.owner != tdb) {
+                       return owner_conflict(tdb, "tdb_lock_free_bucket");
+               }
+
                if (tdb->file->allrecord_lock.ltype == F_WRLCK)
                        return 0;
                return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
index 30338d77abb51deee0e761307e01af588b035725..26ca7b3081b279d5d5db07fadee5a712e3bdd27a 100644 (file)
@@ -463,6 +463,12 @@ enum TDB_ERROR tdb_read_convert(struct tdb_context *tdb, tdb_off_t off,
 void tdb_inc_seqnum(struct tdb_context *tdb);
 
 /* lock.c: */
+/* Print message because another tdb owns a lock we want. */
+enum TDB_ERROR owner_conflict(struct tdb_context *tdb, const char *call);
+
+/* If we fork, we no longer really own locks. */
+bool check_lock_pid(struct tdb_context *tdb, const char *call, bool log);
+
 /* Lock/unlock a range of hashes. */
 enum TDB_ERROR tdb_lock_hashes(struct tdb_context *tdb,
                               tdb_off_t hash_lock, tdb_len_t hash_range,
index 495e1d1bf6f2e6deec85dcac84458a9c6f189ba9..e59874fb2f01db911ac3b698f541e816ec0be7ef 100644 (file)
@@ -149,34 +149,43 @@ static int tdb1_lock_list(struct tdb_context *tdb, int list, int ltype,
        bool check = false;
 
        /* a allrecord lock allows us to avoid per chain locks */
-       if (tdb->file->allrecord_lock.count &&
-           (ltype == tdb->file->allrecord_lock.ltype || ltype == F_RDLCK)) {
-               return 0;
+       if (tdb->file->allrecord_lock.count) {
+               if (!check_lock_pid(tdb, "tdb1_lock_list", true)) {
+                       tdb->last_error = TDB_ERR_LOCK;
+                       return -1;
+               }
+               if (tdb->file->allrecord_lock.owner != tdb) {
+                       tdb->last_error = owner_conflict(tdb, "tdb1_lock_list");
+                       return -1;
+               }
+               if (ltype == tdb->file->allrecord_lock.ltype
+                   || ltype == F_RDLCK) {
+                       return 0;
+               }
+               tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK,
+                                            TDB_LOG_USE_ERROR,
+                                            "tdb1_lock_list:"
+                                            " already have read lock");
+               return -1;
        }
 
-       if (tdb->file->allrecord_lock.count) {
-               tdb->last_error = TDB_ERR_LOCK;
-               ret = -1;
-       } else {
-               /* Only check when we grab first data lock. */
-               check = !have_data_locks(tdb);
-               ret = tdb1_nest_lock(tdb, lock_offset(list), ltype, waitflag);
+       /* Only check when we grab first data lock. */
+       check = !have_data_locks(tdb);
+       ret = tdb1_nest_lock(tdb, lock_offset(list), ltype, waitflag);
+
+       if (ret == 0 && check) {
+               tdb_bool_err berr = tdb1_needs_recovery(tdb);
 
-               if (ret == 0 && check) {
-                       tdb_bool_err berr = tdb1_needs_recovery(tdb);
+               if (berr < 0) {
+                       return -1;
+               }
+               if (berr == true) {
+                       tdb1_nest_unlock(tdb, lock_offset(list), ltype);
 
-                       if (berr < 0) {
+                       if (tdb1_lock_and_recover(tdb) == -1) {
                                return -1;
                        }
-                       if (berr == true) {
-                               tdb1_nest_unlock(tdb, lock_offset(list), ltype);
-
-                               if (tdb1_lock_and_recover(tdb) == -1) {
-                                       return -1;
-                               }
-                               return tdb1_lock_list(tdb, list, ltype,
-                                                     waitflag);
-                       }
+                       return tdb1_lock_list(tdb, list, ltype, waitflag);
                }
        }
        return ret;
@@ -222,6 +231,10 @@ int tdb1_unlock(struct tdb_context *tdb, int list, int ltype)
        /* a global lock allows us to avoid per chain locks */
        if (tdb->file->allrecord_lock.count &&
            (ltype == tdb->file->allrecord_lock.ltype || ltype == F_RDLCK)) {
+               if (tdb->file->allrecord_lock.owner != tdb) {
+                       tdb->last_error = owner_conflict(tdb, "tdb1_unlock");
+                       return -1;
+               }
                return 0;
        }
 
@@ -314,9 +327,9 @@ int tdb1_allrecord_lock(struct tdb_context *tdb, int ltype,
                return -1;
        }
 
-       /* FIXME: Temporary cast. */
-       tdb->file->allrecord_lock.owner = (void *)(struct tdb_context *)tdb;
+       tdb->file->allrecord_lock.owner = tdb;
        tdb->file->allrecord_lock.count = 1;
+       tdb->file->locker = getpid();
        /* If it's upgradable, it's actually exclusive so we can treat
         * it as a write lock. */
        tdb->file->allrecord_lock.ltype = upgradable ? F_WRLCK : ltype;
@@ -362,6 +375,11 @@ int tdb1_allrecord_unlock(struct tdb_context *tdb, int ltype)
        }
 
        if (tdb->file->allrecord_lock.count > 1) {
+               if (tdb->file->allrecord_lock.owner != tdb) {
+                       tdb->last_error
+                               = owner_conflict(tdb, "tdb1_allrecord_unlock");
+                       return -1;
+               }
                tdb->file->allrecord_lock.count--;
                return 0;
        }
@@ -412,6 +430,15 @@ int tdb1_chainunlock_read(struct tdb_context *tdb, TDB_DATA key)
 int tdb1_lock_record(struct tdb_context *tdb, tdb1_off_t off)
 {
        if (tdb->file->allrecord_lock.count) {
+               if (!check_lock_pid(tdb, "tdb1_lock_record", true)) {
+                       tdb->last_error = TDB_ERR_LOCK;
+                       return -1;
+               }
+               if (tdb->file->allrecord_lock.owner != tdb) {
+                       tdb->last_error = owner_conflict(tdb,
+                                                        "tdb1_lock_record");
+                       return -1;
+               }
                return 0;
        }
        return off ? tdb1_brlock(tdb, F_RDLCK, off, 1, TDB_LOCK_WAIT) : 0;
@@ -429,6 +456,15 @@ int tdb1_write_lock_record(struct tdb_context *tdb, tdb1_off_t off)
                if (i->off == off)
                        return -1;
        if (tdb->file->allrecord_lock.count) {
+               if (!check_lock_pid(tdb, "tdb1_write_lock_record", true)) {
+                       tdb->last_error = TDB_ERR_LOCK;
+                       return -1;
+               }
+               if (tdb->file->allrecord_lock.owner != tdb) {
+                       tdb->last_error
+                               = owner_conflict(tdb, "tdb1_write_lock_record");
+                       return -1;
+               }
                if (tdb->file->allrecord_lock.ltype == F_WRLCK) {
                        return 0;
                }
@@ -440,6 +476,12 @@ int tdb1_write_lock_record(struct tdb_context *tdb, tdb1_off_t off)
 int tdb1_write_unlock_record(struct tdb_context *tdb, tdb1_off_t off)
 {
        if (tdb->file->allrecord_lock.count) {
+               if (tdb->file->allrecord_lock.owner != tdb) {
+                       tdb->last_error
+                               = owner_conflict(tdb,
+                                                "tdb1_write_unlock_record");
+                       return -1;
+               }
                return 0;
        }
        return tdb1_brunlock(tdb, F_WRLCK, off, 1);
@@ -452,6 +494,11 @@ int tdb1_unlock_record(struct tdb_context *tdb, tdb1_off_t off)
        uint32_t count = 0;
 
        if (tdb->file->allrecord_lock.count) {
+               if (tdb->file->allrecord_lock.owner != tdb) {
+                       tdb->last_error = owner_conflict(tdb,
+                                                        "tdb1_unlock_record");
+                       return -1;
+               }
                return 0;
        }