From: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
To: "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>
Cc: Brian King <brking@linux.vnet.ibm.com>
Subject: SHOST_RECOVERY hang with host_busy < host_failed
Date: Mon, 16 May 2016 15:37:46 -0700 [thread overview]
Message-ID: <573A4BBA.9010608@linux.vnet.ibm.com> (raw)
I'm seeing a non-deterministic I/O hang with the ibmvfc driver when we
migrate a guest/partition to a different machine. So, on the occasions
when this hits the systems becomes unresponsive blocked on I/O. I
started by inspecting Scsi_Host of the driver which shows shost->state =
SHOST_RECOVERY explaining the blocked I/O. What I found a little weird
however was shost->host_failed > shost->host_busy.
>From the EH documentation SHOST_RECOVERY is set by scsi_eh_scmd_add thus
blocking any new scmd's from the block queue to the host. So, every
scmnd in flight either completes or fails with failed commands being
inclusive of busy commands count, and the EH thread started once all
busy commands are failed commands (ie. host_busy == host_failed). So,
this should mean host_failed should never by greater than host_busy,
correct?
-Tyrel
reply other threads:[~2016-05-16 22:37 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=573A4BBA.9010608@linux.vnet.ibm.com \
--to=tyreld@linux.vnet.ibm.com \
--cc=brking@linux.vnet.ibm.com \
--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).