From: mikeb <mikeb@openbsd.org>
Date: Thu, 15 Jun 2017 18:00:26 +0000 (+0000)
Subject: Put back copying of the response message into the polling callback
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=332f60c207f24f870790d21cf9c40dd92ff17430;p=openbsd

Put back copying of the response message into the polling callback

The response message is allocated on the stack of hvs_intr and its
content is valid during a single message processing loop iteration.
Due to the fact that polled transfers finish completion in a callee
context, the cached pointer to the response message becomes stale
very quickly.  To avoid this situation the poll completion callback
needs to make sure the content of the response is provided to the
next completion routine.
---

diff --git a/sys/dev/pv/hvs.c b/sys/dev/pv/hvs.c
index 0fe13372a50..fc4df381b9c 100644
--- a/sys/dev/pv/hvs.c
+++ b/sys/dev/pv/hvs.c
@@ -245,7 +245,7 @@ void	hvs_scsi_probe(void *arg);
 void	hvs_scsi_done(struct scsi_xfer *, int);
 
 int	hvs_connect(struct hvs_softc *);
-void	hvs_cmd_done(struct hvs_ccb *);
+void	hvs_empty_done(struct hvs_ccb *);
 
 int	hvs_alloc_ccbs(struct hvs_softc *);
 void	hvs_free_ccbs(struct hvs_softc *);
@@ -469,8 +469,15 @@ hvs_start(struct hvs_ccb *ccb)
 void
 hvs_poll_done(struct hvs_ccb *ccb)
 {
+	struct hvs_softc *sc = ccb->ccb_softc;
 	int *rv = ccb->ccb_cookie;
 
+	if (ccb->ccb_cmd) {
+		memcpy(&sc->sc_resp, ccb->ccb_cmd, HVS_CMD_SIZE);
+		ccb->ccb_cmd = &sc->sc_resp;
+	} else
+		memset(&sc->sc_resp, 0, HVS_CMD_SIZE);
+
 	*rv = 0;
 }
 
@@ -480,7 +487,7 @@ hvs_poll(struct hvs_ccb *ccb)
 	struct hvs_softc *sc = ccb->ccb_softc;
 	void (*done)(struct hvs_ccb *);
 	void *cookie;
-	int rv = 1;
+	int s, rv = 1;
 
 	done = ccb->ccb_done;
 	cookie = ccb->ccb_cookie;
@@ -495,7 +502,9 @@ hvs_poll(struct hvs_ccb *ccb)
 	}
 
 	while (rv == 1) {
+		s = splbio();
 		hvs_intr(sc);
+		splx(s);
 		delay(10);
 	}
 
@@ -697,7 +706,7 @@ hvs_connect(struct hvs_softc *sc)
 		return (-1);
 	}
 
-	ccb->ccb_done = hvs_cmd_done;
+	ccb->ccb_done = hvs_empty_done;
 
 	cmd = (struct hvs_cmd_ver *)&ucmd;
 
@@ -816,12 +825,9 @@ hvs_connect(struct hvs_softc *sc)
 }
 
 void
-hvs_cmd_done(struct hvs_ccb *ccb)
+hvs_empty_done(struct hvs_ccb *ccb)
 {
-	struct hvs_softc *sc = ccb->ccb_softc;
-
-	if (ccb->ccb_cmd)
-		memcpy(&sc->sc_resp, ccb->ccb_cmd, HVS_CMD_SIZE);
+	/* nothing */
 }
 
 int