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Date: Mon, 17 Feb 2020 23:01:17 +0300
From: Konstantin Osipov <kostja.osipov@gmail.com>
Message-ID: <20200217200117.GA12248@atlas>
References: <20200217155953.25803-1-gorcunov@gmail.com>
 <20200217155953.25803-5-gorcunov@gmail.com>
 <20200217171940.GD11553@atlas> <20200217190508.GA2482@uranus>
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Subject: Re: [Tarantool-patches] [PATCH 4/4] box/txn: fix nil dereference in
	txn_rollback
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To: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: tml <tarantool-patches@dev.tarantool.org>

* Cyrill Gorcunov <gorcunov@gmail.com> [20/02/17 22:07]:
> b) error during journal_write
> 
> txn_write
>   txn_write_to_wal
>     journal_write
>       wal_write
>         ...
>         entry->res = -1;
>         return -1;
>   txn_rollback(with fiber.txn != NULL), which
>   is fine.

After you remove journal_entry_complete_cb from fail: branch of
wal_write(), if you set txn to null only after successful journal_write, you'll
be fine. On failure, the rollback will be done by txn_write().

> Guys, do I miss something obvious? The key moment
> is dropping journal_entry_complete call from wal.c
> on error path and defer setting fiber.txn = NULL
> until journal_write passed without errors.

Don't know how obvious this is, but it is something both me and
Georgy are suggesting it seems.

 

-- 
Konstantin Osipov, Moscow, Russia