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| author | Marko Mäkelä <marko.makela@mariadb.com> | 2021-10-21 12:29:33 +0300 |
|---|---|---|
| committer | Marko Mäkelä <marko.makela@mariadb.com> | 2021-10-21 12:56:59 +0300 |
| commit | c484a358c897413be390d03bdcb8dc4d70c7d1c3 (patch) | |
| tree | 8e1f51ce63b870594c419c239cbb02cb8fb953b1 | |
| parent | 8ce8c269f461b7a578cf0bb5cce18f1d83ebeb9b (diff) | |
| download | mariadb-git-c484a358c897413be390d03bdcb8dc4d70c7d1c3.tar.gz | |
MDEV-26864 Race condition between transaction commit and undo log truncation
trx_commit_in_memory(): Do not release the rseg reference before
trx_undo_commit_cleanup() has been invoked and the current transaction
is truly done with the rollback segment. The purpose of the reference
count is to prevent data races with trx_purge_truncate_history().
This is based on
mysql/mysql-server@ac79aa1522f33e6eb912133a81fa2614db764c9c.
| -rw-r--r-- | storage/innobase/trx/trx0trx.cc | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/storage/innobase/trx/trx0trx.cc b/storage/innobase/trx/trx0trx.cc index 3e558a7181d..6669d15a31b 100644 --- a/storage/innobase/trx/trx0trx.cc +++ b/storage/innobase/trx/trx0trx.cc @@ -1775,12 +1775,7 @@ trx_commit_in_memory( ut_ad(!trx->rsegs.m_redo.update_undo); - if (trx_rseg_t* rseg = trx->rsegs.m_redo.rseg) { - mutex_enter(&rseg->mutex); - ut_ad(rseg->trx_ref_count > 0); - --rseg->trx_ref_count; - mutex_exit(&rseg->mutex); - + if (ut_d(trx_rseg_t* rseg =) trx->rsegs.m_redo.rseg) { if (trx_undo_t*& insert = trx->rsegs.m_redo.insert_undo) { ut_ad(insert->rseg == rseg); trx_undo_commit_cleanup(insert, false); @@ -1849,6 +1844,15 @@ trx_commit_in_memory( ut_ad(!trx->rsegs.m_noredo.undo); + /* Only after trx_undo_commit_cleanup() it is safe to release + our rseg reference. */ + if (trx_rseg_t* rseg = trx->rsegs.m_redo.rseg) { + mutex_enter(&rseg->mutex); + ut_ad(rseg->trx_ref_count > 0); + --rseg->trx_ref_count; + mutex_exit(&rseg->mutex); + } + /* Free all savepoints, starting from the first. */ trx_named_savept_t* savep = UT_LIST_GET_FIRST(trx->trx_savepoints); |