From: Swen Schillig <swen@vnet.ibm.com>
To: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: James Bottomley <James.Bottomley@steeleye.com>,
Christof Schmitt <christof.schmitt@de.ibm.com>,
linux-scsi@vger.kernel.org,
Linux on 390 Port <LINUX-390@vm.marist.edu>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] zfcp: add some internal zfcp adapter statistics
Date: Mon, 5 Nov 2007 16:12:43 +0100 [thread overview]
Message-ID: <200711051612.44273.swen@vnet.ibm.com> (raw)
In-Reply-To: <20071103091722.GA7807@osiris.boeblingen.de.ibm.com>
On Saturday 03 November 2007 10:17, Heiko Carstens wrote:
> > +static void zfcp_fsf_req_latency(struct zfcp_fsf_req *fsf_req)
> > +{
> > + struct fsf_qual_latency_info *lat_inf;
> > + struct zfcp_unit *unit;
> > +
> > + lat_inf = &fsf_req->qtcb->prefix.prot_status_qual.latency_info;
> > + unit = fsf_req->unit;
> > +
> > + switch (fsf_req->qtcb->bottom.io.data_direction) {
> > + case FSF_DATADIR_READ:
> > + unit->latencies.read.channel += lat_inf->channel_lat;
> > + unit->latencies.read.fabric += lat_inf->fabric_lat;
> > + unit->latencies.read.counter++;
> > + break;
> > + case FSF_DATADIR_WRITE:
> > + unit->latencies.write.channel += lat_inf->channel_lat;
> > + unit->latencies.write.fabric += lat_inf->fabric_lat;
> > + unit->latencies.write.counter++;
> > + break;
> > + case FSF_DATADIR_CMND:
> > + unit->latencies.cmd.channel += lat_inf->channel_lat;
> > + unit->latencies.cmd.fabric += lat_inf->fabric_lat;
> > + unit->latencies.cmd.counter++;
> > + break;
> > + }
> > +}
>
> These statistics are concurrently updated from several cpus without
> any locking. That looks like a bug.
>
> > +zfcp_sysfs_unit_##_name##_latency_show(struct device *dev, \
> > + struct device_attribute *attr, \
> > + char *buf) { \
> > + struct scsi_device *sdev = to_scsi_device(dev); \
> > + struct zfcp_unit *unit = sdev->hostdata; \
> > + struct zfcp_latencies *lat = &unit->latencies; \
> > + struct zfcp_adapter *adapter = unit->port->adapter; \
> > + \
> > + return sprintf(buf, "%u %u %u\n", \
> > + lat->_name.fabric * adapter->timer_ticks / 1000, \
> > + lat->_name.channel * adapter->timer_ticks / 1000,\
> > + lat->_name.counter); \
>
> In addition they can be read concurrently from userspace without any
> locking... Since you put several values together in the output I assume
> this is supposed to be some sort of snapshot, which it currently isn't.
>
> > +static int
> > +zfcp_sysfs_adapter_ex_config(struct class_device *cdev,
> > + struct fsf_qtcb_bottom_config **qtcb_config)
> > +{
> > + struct Scsi_Host *scsi_host = class_to_shost(cdev);
> > + struct zfcp_adapter *adapter = (struct zfcp_adapter *)
> > + scsi_host->hostdata[0];
> > +
> > + if (!(adapter->adapter_features & FSF_FEATURE_MEASUREMENT_DATA)) {
> > + ZFCP_LOG_NORMAL("error: Enhanced measurement feature not "
> > + "supported");
> > + return -EOPNOTSUPP;
> > + }
> > +
> > + *qtcb_config = kzalloc(sizeof(struct fsf_qtcb_bottom_config),
> > + GFP_KERNEL);
> > + if (!*qtcb_config)
> > + return -ENOMEM;
> > +
> > + return zfcp_fsf_exchange_config_data_sync(adapter, *qtcb_config);
> > +}
> > +
> > +static ssize_t
> > +zfcp_sysfs_adapter_request_show(struct class_device *cdev, char *buf)
> > +{
> > + struct fsf_qtcb_bottom_config *qtcb_config;
> > + int retval;
> > +
> > + retval = zfcp_sysfs_adapter_ex_config(cdev, &qtcb_config);
> > +
> > + if (!retval)
> > + retval = sprintf(buf, "%lu %lu %lu\n",
> > + qtcb_config->stat_info.input_req,
> > + qtcb_config->stat_info.output_req,
> > + qtcb_config->stat_info.control_req);
> > +
> > + kfree(qtcb_config);
> > + return retval;
> > +}
>
> You're going to call kfree with some random value if the adapter doesn't
> support the measurement data feature.
>
Ok, valid points.
I changed the patch to meet the above described issues.
Before I will post the modified version I want to do some testing (and an internal review).
The updated version will follow soon (hopefully this week), thanks for reviewing.
Cheers Swen
next prev parent reply other threads:[~2007-11-05 15:12 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-31 10:33 [PATCH] zfcp: add some internal zfcp adapter statistics Swen Schillig
2007-11-03 9:17 ` Heiko Carstens
2007-11-03 9:40 ` Heiko Carstens
2007-11-05 11:35 ` Swen Schillig
2007-11-05 15:12 ` Swen Schillig [this message]
2007-11-25 11:16 ` James Bottomley
2007-11-26 10:23 ` Swen Schillig
2007-12-06 9:40 ` Swen Schillig
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=200711051612.44273.swen@vnet.ibm.com \
--to=swen@vnet.ibm.com \
--cc=James.Bottomley@steeleye.com \
--cc=LINUX-390@vm.marist.edu \
--cc=christof.schmitt@de.ibm.com \
--cc=heiko.carstens@de.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).