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From: Peter Maydell <peter.maydell@linaro.org>
Date: Mon, 30 Jul 2018 18:57:13 +0100
Message-ID: <CAFEAcA8N26yjrLeaDzkoJfx50Rd5h_y9hHVA8W19L9q1EOhfMA@mail.gmail.com>
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Subject: Re: [Qemu-devel] [PATCH v3 5/7] loader: add rom transaction API
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To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: QEMU Developers <qemu-devel@nongnu.org>, =?UTF-8?Q?Steffen_G=C3=B6rtz?= <mail@steffen-goertz.de>, Alistair Francis <alistair@alistair23.me>, Liviu Ionescu <ilg@livius.net>, qemu-arm <qemu-arm@nongnu.org>, Julia Suvorova <jusual@mail.ru>, Subbaraya Sundeep <sundeep.lkml@gmail.com>, Su Hang <suhang16@mails.ucas.ac.cn>, Steffen Gortz <qemu.ml@steffen-goertz.de>, Jim Mussared <jim@groklearning.com>, Joel Stanley <joel@jms.id.au>

On 25 July 2018 at 09:59, Stefan Hajnoczi <stefanha@redhat.com> wrote:
> Image file loaders may add a series of roms.  If an error occurs partway
> through loading there is no easy way to drop previously added roms.
>
> This patch adds a transaction mechanism that works like this:
>
>   rom_transaction_begin();
>   ...call rom_add_*()...
>   rom_transaction_end(ok);
>
> If ok is false then roms added in this transaction are dropped.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> +void rom_transaction_end(bool commit)
> +{
> +    Rom *rom;
> +    Rom *tmp;
> +
> +    QTAILQ_FOREACH_SAFE(rom, &roms, next, tmp) {
> +        if (rom->committed) {
> +            continue;
> +        }
> +        if (commit) {
> +            rom->committed = true;
> +        } else {
> +            QTAILQ_REMOVE(&roms, rom, next);
> +            g_free(rom->data);
> +            g_free(rom->path);
> +            g_free(rom->name);
> +            g_free(rom->fw_dir);
> +            g_free(rom->fw_file);
> +            g_free(rom);

Is it worth having a rom_free() function so we can
share the "free all the pointers" code between this
and the error-exit codepath at the end of rom_add_file() ?

Either way
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM