From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Christie Subject: Re: [PATCH] libiscsi: Fix iscsi_check_transport_timeouts possible infinite loop Date: Thu, 02 Jul 2015 15:11:00 -0500 Message-ID: <55959AD4.8050209@cs.wisc.edu> References: <1435676153-27822-1-git-send-email-sagig@mellanox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from sabe.cs.wisc.edu ([128.105.6.20]:48696 "EHLO sabe.cs.wisc.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754067AbbGBULT (ORCPT ); Thu, 2 Jul 2015 16:11:19 -0400 In-Reply-To: <1435676153-27822-1-git-send-email-sagig@mellanox.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Sagi Grimberg , linux-scsi@vger.kernel.org Cc: James Bottomley , Ariel Nahum On 6/30/15, 9:55 AM, Sagi Grimberg wrote: > From: Ariel Nahum > > Connection last_ping is not being updated when iscsi_send_nopout fails. > Not updating the last_ping will cause firing a timer to a past time > (last_ping + ping_tmo < current_time) which triggers an infinite loop of > iscsi_check_transport_timeouts() and hogs the cpu. > > Fix this issue by checking the return value of iscsi_send_nopout. > If it fails set the next_timeout to one second later. > > Signed-off-by: Ariel Nahum > Signed-off-by: Sagi Grimberg > --- > drivers/scsi/libiscsi.c | 15 ++++++++++----- > 1 files changed, 10 insertions(+), 5 deletions(-) > > diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c > index 8053f24..1ea4213 100644 > --- a/drivers/scsi/libiscsi.c > +++ b/drivers/scsi/libiscsi.c > @@ -979,13 +979,13 @@ static void iscsi_tmf_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr) > wake_up(&conn->ehwait); > } > > -static void iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr) > +static int iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr) > { > struct iscsi_nopout hdr; > struct iscsi_task *task; > > if (!rhdr && conn->ping_task) > - return; > + return -EINVAL; > > memset(&hdr, 0, sizeof(struct iscsi_nopout)); > hdr.opcode = ISCSI_OP_NOOP_OUT | ISCSI_OP_IMMEDIATE; > @@ -999,13 +999,16 @@ static void iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr) > hdr.ttt = RESERVED_ITT; > > task = __iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)&hdr, NULL, 0); > - if (!task) > + if (!task) { Are you hitting the failure case in the first chunk of the patch or the failure right above? If the latter, why is it failing? > iscsi_conn_printk(KERN_ERR, conn, "Could not send nopout\n"); > + return -EIO; > + } > else if (!rhdr) { I think the coding style is wrong. It should be: if () { } else if { } > /* only track our nops */ > conn->ping_task = task; > conn->last_ping = jiffies; > } > + return 0; > } > > static int iscsi_nop_out_rsp(struct iscsi_task *task, > @@ -2095,8 +2098,10 @@ static void iscsi_check_transport_timeouts(unsigned long data) > if (time_before_eq(last_recv + recv_timeout, jiffies)) { > /* send a ping to try to provoke some traffic */ > ISCSI_DBG_CONN(conn, "Sending nopout as ping\n"); > - iscsi_send_nopout(conn, NULL); > - next_timeout = conn->last_ping + (conn->ping_timeout * HZ); > + if (iscsi_send_nopout(conn, NULL)) > + next_timeout = jiffies + (1 * HZ); > + else > + next_timeout = conn->last_ping + (conn->ping_timeout * HZ); > } else > next_timeout = last_recv + recv_timeout; > > n