diff options
Diffstat (limited to 'pkgs/development/libraries/db/register-race-fix.patch')
| -rw-r--r-- | pkgs/development/libraries/db/register-race-fix.patch | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/pkgs/development/libraries/db/register-race-fix.patch b/pkgs/development/libraries/db/register-race-fix.patch new file mode 100644 index 00000000000..bb05c966e5b --- /dev/null +++ b/pkgs/development/libraries/db/register-race-fix.patch @@ -0,0 +1,47 @@ +diff -rc db-4.5.20-orig/env/env_register.c db-4.5.20/env/env_register.c +*** db-4.5.20-orig/env/env_register.c 2006-09-09 16:29:04.000000000 +0200 +--- db-4.5.20/env/env_register.c 2007-05-16 21:13:27.000000000 +0200 +*************** +*** 255,260 **** +--- 255,262 ---- + buf[nr - 1] = '\0'; + } + ++ //sleep(3); ++ + pos = (off_t)lcnt * PID_LEN; + if (REGISTRY_LOCK(dbenv, pos, 1) == 0) { + if ((ret = REGISTRY_UNLOCK(dbenv, pos)) != 0) +*************** +*** 361,366 **** +--- 363,392 ---- + if (recovery_failed) + goto err; + ++ //sleep(5); ++ ++ /* ++ * Acquire an exclusive lock to prevent a race like this: ++ * ++ * 1) Process X is about to exit and process Y is just ++ * starting. ++ * 2) Process Y reads X's slot. ++ * 3) Process X clears its slot. ++ * 4) Process Y sees that X's slot isn't cleared yet (since it ++ * just read the old value). ++ * 5) Process X closes the registry, releases the lock on its ++ * slot. ++ * 6) Process Y tries to acquire X's slot and succeeds, so it ++ * concludes that X died and recovery is needed. ++ * ++ * A more efficient solution to this problem would be to let ++ * __envreg_add acquire the lock on a slot first, and *then* ++ * read the slot (instead of the other way around). Then we ++ * wouldn't need the exclusive lock here. ++ */ ++ if ((ret = REGISTRY_EXCL_LOCK(dbenv, 0)) != 0) ++ goto err; ++ + /* + * Why isn't an exclusive lock necessary to discard a DB_ENV handle? + * |