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 18:30:45 +0000
From:   Long Li <longli@...rosoft.com>
To:     Pavel Shilovsky <piastryyy@...il.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>
Subject: RE: [PATCH resend] cifs: Do not modify mid entry after submitting I/O
 in cifs_call_async



> -----Original Message-----
> From: Pavel Shilovsky [mailto:piastryyy@...il.com]
> Sent: Wednesday, June 28, 2017 11:23 AM
> To: Long Li <longli@...rosoft.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
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-cifs"
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> 
> Looks good. Could you please add an additional comment describing the
> behavior in the code?

Sure, will do.

> 
> --
> Best regards,
> Pavel Shilovsky