linux-kernel - RE: [[PATCH v1] 25/37] [CIFS] SMBD: Support SMBD idle connection timer

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CY4PR21MB01829CD26D97DF63CAB08666CE8C0@CY4PR21MB0182.namprd21.prod.outlook.com>
Date:   Mon, 14 Aug 2017 23:29:38 +0000
From:   Long Li <longli@...rosoft.com>
To:     Tom Talpey <ttalpey@...rosoft.com>,
        Steve French <sfrench@...ba.org>,
        "linux-cifs@...r.kernel.org" <linux-cifs@...r.kernel.org>,
        "samba-technical@...ts.samba.org" <samba-technical@...ts.samba.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [[PATCH v1] 25/37] [CIFS] SMBD: Support SMBD idle connection
 timer



> -----Original Message-----
> From: Tom Talpey
> Sent: Monday, August 14, 2017 2:12 PM
> To: Long Li <longli@...rosoft.com>; Steve French <sfrench@...ba.org>;
> linux-cifs@...r.kernel.org; samba-technical@...ts.samba.org; linux-
> kernel@...r.kernel.org
> Cc: Long Li <longli@...rosoft.com>
> Subject: RE: [[PATCH v1] 25/37] [CIFS] SMBD: Support SMBD idle connection
> timer
> 
> > -----Original Message-----
> > From: linux-cifs-owner@...r.kernel.org [mailto:linux-cifs-
> > owner@...r.kernel.org] On Behalf Of Long Li
> > Sent: Wednesday, August 2, 2017 4:11 PM
> > To: Steve French <sfrench@...ba.org>; linux-cifs@...r.kernel.org;
> > samba- technical@...ts.samba.org; linux-kernel@...r.kernel.org
> > Cc: Long Li <longli@...rosoft.com>
> > Subject: [[PATCH v1] 25/37] [CIFS] SMBD: Support SMBD idle connection
> > timer
> >
> > +static int keep_alive_interval = 120;
> 
> This is the recommended value, but not the only possibility.
> 
> > @@ -1348,6 +1369,10 @@ struct cifs_rdma_info*
> cifs_create_rdma_session(
> >         init_waitqueue_head(&info->wait_send_queue);
> >         init_waitqueue_head(&info->wait_reassembly_queue);
> >
> > +       INIT_DELAYED_WORK(&info->idle_timer_work,
> idle_connection_timer);
> > +       schedule_delayed_work(&info->idle_timer_work,
> > +               info->keep_alive_interval*HZ);
> > +
> 
> This initialization is ok, but the timer should be rescheduled (extended) any
> time any packet is sent. There is no need to perform keepalives on an active
> SMB Direct connection.

My feeling is that rescheduling on a work queue for every packet is sent is not efficient, especially under heavy conditions.

Firing it every 120 seconds doesn't seem to be big waste and may actually save some CPU.

> 
> Tom.