linux-kernel - Re: [PATCH resend] cifs: Do not modify mid entry after submitting I/O in cifs_call

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Date:   Wed, 28 Jun 2017 11:23:20 -0700
From:   Pavel Shilovsky <piastryyy@...il.com>
To:     Long Li <longli@...hange.microsoft.com>
Cc:     Steve French <sfrench@...ba.org>,
        linux-cifs <linux-cifs@...r.kernel.org>,
        samba-technical <samba-technical@...ts.samba.org>,
        Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Long Li <longli@...rosoft.com>
Subject: Re: [PATCH resend] cifs: Do not modify mid entry after submitting I/O
 in cifs_call_async

2017-06-28 11:05 GMT-07:00 Long Li <longli@...hange.microsoft.com>:
> From: Long Li <longli@...rosoft.com>
>
> In cifs_call_async, server response may return as soon as I/O is submitted.
> Because mid entry is freed on the return path, do not modify it after I/O is
> submitted.
>
> Signed-off-by: Long Li <longli@...rosoft.com>
> ---
>  fs/cifs/transport.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
> index 47a125e..ba62aaf 100644
> --- a/fs/cifs/transport.c
> +++ b/fs/cifs/transport.c
> @@ -537,10 +537,10 @@ cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
>         spin_unlock(&GlobalMid_Lock);
>
>
> +       cifs_save_when_sent(mid);
>         cifs_in_send_inc(server);
>         rc = smb_send_rqst(server, rqst, flags);
>         cifs_in_send_dec(server);
> -       cifs_save_when_sent(mid);
>
>         if (rc < 0) {
>                 server->sequence_number -= 2;
> --
> 2.7.4
>
> --
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Looks good. Could you please add an additional comment describing the
behavior in the code?

--
Best regards,
Pavel Shilovsky