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Tue, 13 Apr 2021 18:24:12 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CC253A405B; Tue, 13 Apr 2021 18:24:12 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Tue, 13 Apr 2021 18:24:12 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 4958) id 7E079E0482; Tue, 13 Apr 2021 20:24:12 +0200 (CEST) From: Eric Farman To: Cornelia Huck , Halil Pasic Cc: Matthew Rosato , Jared Rossi , linux-s390@vger.kernel.org, kvm@vger.kernel.org, Eric Farman Subject: [RFC PATCH v4 2/4] vfio-ccw: Check workqueue before doing START Date: Tue, 13 Apr 2021 20:24:08 +0200 Message-Id: <20210413182410.1396170-3-farman@linux.ibm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210413182410.1396170-1-farman@linux.ibm.com> References: <20210413182410.1396170-1-farman@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: PgC-abe-jtYUxGSiacaW4J5-nh9Qt1gT X-Proofpoint-GUID: u3da3qWCNlNWuaOhYtrVlUb6Sl6manrA X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-04-13_12:2021-04-13,2021-04-13 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 mlxscore=0 lowpriorityscore=0 phishscore=0 suspectscore=0 clxscore=1015 malwarescore=0 spamscore=0 bulkscore=0 mlxlogscore=664 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104060000 definitions=main-2104130122 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org When an interrupt is received via the IRQ, the bulk of the work is stacked on a workqueue for later processing. Which means that a concurrent START or HALT/CLEAR operation (via the async_region) will race with this process and require some serialization. Once we have all our locks acquired, let's just look to see if we're in a window where the process has been started from the IRQ, but not yet picked up by vfio-ccw to clean up an I/O. If there is, mark the request as BUSY so it can be redriven. Signed-off-by: Eric Farman --- drivers/s390/cio/vfio_ccw_fsm.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c index 23e61aa638e4..92d638f10b27 100644 --- a/drivers/s390/cio/vfio_ccw_fsm.c +++ b/drivers/s390/cio/vfio_ccw_fsm.c @@ -28,6 +28,11 @@ static int fsm_io_helper(struct vfio_ccw_private *private) spin_lock_irqsave(sch->lock, flags); + if (work_pending(&private->io_work)) { + ret = -EBUSY; + goto out; + } + orb = cp_get_orb(&private->cp, (u32)(addr_t)sch, sch->lpm); if (!orb) { ret = -EIO; -- 2.25.1