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mdbx: avoid tsan-trap in mdb_txn_renew0() by mti_txnid.

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Change-Id: Ia91bb913fc99880ec34fd0bf6fc9396555c6a56f
This commit is contained in:
Leo Yuriev 2015-12-05 12:19:29 +03:00
parent 50c480e2de
commit 5bc0a76899
1 changed files with 21 additions and 12 deletions
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33
mdb.c
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@ -2695,6 +2695,25 @@ mdb_reader_pid(MDB_env *env, int op, pid_t pid)
}
}
static ATTRIBUTE_NO_SANITIZE_THREAD
txnid_t lead_txnid__tsan_workaround(MDB_txn *txn, MDB_reader *r)
{
while(1) { /* LY: Retry on a race, ITS#7970. */
MDB_meta *meta = mdb_meta_head_r(txn->mt_env);
txnid_t lead = meta->mm_txnid;
r->mr_txnid = lead;
mdb_coherent_barrier();
/* Copy the DB info and flags */
memcpy(txn->mt_dbs, meta->mm_dbs, CORE_DBS * sizeof(MDB_db));
txn->mt_next_pgno = meta->mm_last_pg+1;
if (likely(lead == txn->mt_env->me_txns->mti_txnid))
return lead;
#if defined(__i386__) || defined(__x86_64__)
__asm__ __volatile__("pause");
#endif
}
}
/** Common code for #mdb_txn_begin() and #mdb_txn_renew().
* @param[in] txn the transaction handle to initialize
* @return 0 on success, non-zero on failure.
@ -2703,7 +2722,6 @@ static int
mdb_txn_renew0(MDB_txn *txn, unsigned flags)
{
MDB_env *env = txn->mt_env;
MDB_meta *meta;
unsigned i, nr;
uint16_t x;
int rc, new_notls = 0;
@ -2794,16 +2812,7 @@ mdb_txn_renew0(MDB_txn *txn, unsigned flags)
}
}
do { /* LY: Retry on a race, ITS#7970. */
meta = mdb_meta_head_r(env);
r->mr_txnid = meta->mm_txnid;
mdb_coherent_barrier();
/* Copy the DB info and flags */
memcpy(txn->mt_dbs, meta->mm_dbs, CORE_DBS * sizeof(MDB_db));
txn->mt_next_pgno = meta->mm_last_pg+1;
} while(unlikely(r->mr_txnid != env->me_txns->mti_txnid));
txn->mt_txnid = r->mr_txnid;
txn->mt_txnid = lead_txnid__tsan_workaround(txn, r);
txn->mt_u.reader = r;
txn->mt_dbxs = env->me_dbxs; /* mostly static anyway */
} else {
@ -2812,7 +2821,7 @@ mdb_txn_renew0(MDB_txn *txn, unsigned flags)
if (unlikely(rc))
return rc;
meta = mdb_meta_head_w(env);
MDB_meta *meta = mdb_meta_head_w(env);
txn->mt_txnid = meta->mm_txnid + 1;
txn->mt_flags = flags;