Add a callback to the ada(4) driver so that it knows when GEOM has released

references to it.

This is the functional equivalent to change r237518, which added this
functionality to the cd(4) and da(4) drivers.

This fix prevents a panic caused by GEOM calling adaopen() while the device
is going away.  We now keep the device around until GEOM has finished
cleaning up its state.

ata_da.c:	In adaregister(), add a d_gone callback to the GEOM disk
		structure registered for the ada driver.  Increment the
		peripheral reference count for GEOM.

		Add a new callback, adadiskgonecb(), that GEOM calls when
		it is done with its resources.  This callback releases the
		reference acquired in adaregister().

Submitted by:	Po-Li Soong
Sponsored by:	Spectra Logic
MFC After:	5 days

1 files changed, 26 insertions, 0 deletions

diff --git a/sys/cam/ata/ata_da.c b/sys/cam/ata/ata_da.c
index c40edba..bf3e683 100644
--- a/sys/cam/ata/ata_da.c
+++ b/sys/cam/ata/ata_da.c
@@ -801,6 +801,20 @@ adainit(void)
 	}
 }
 
+/*
+ * Callback from GEOM, called when it has finished cleaning up its
+ * resources.
+ */
+static void
+adadiskgonecb(struct disk *dp)
+{
+	struct cam_periph *periph;
+
+	periph = (struct cam_periph *)dp->d_drv1;
+
+	cam_periph_release(periph);
+}
+
 static void
 adaoninvalidate(struct cam_periph *periph)
 {
@@ -1157,6 +1171,7 @@ adaregister(struct cam_periph *periph, void *arg)
 	softc->disk->d_strategy = adastrategy;
 	softc->disk->d_getattr = adagetattr;
 	softc->disk->d_dump = adadump;
+	softc->disk->d_gone = adadiskgonecb;
 	softc->disk->d_name = "ada";
 	softc->disk->d_drv1 = periph;
 	maxio = cpi.maxio;		/* Honor max I/O size of SIM */
@@ -1222,6 +1237,17 @@ adaregister(struct cam_periph *periph, void *arg)
 		}
 	} else
 		legacy_id = -1;
+	/*
+	 * Acquire a reference to the periph before we register with GEOM.
+	 * We'll release this reference once GEOM calls us back (via
+	 * adadiskgonecb()) telling us that our provider has been freed.
+	 */
+	if (cam_periph_acquire(periph) != CAM_REQ_CMP) {
+		xpt_print(periph->path, "%s: lost periph during "
+			  "registration!\n", __func__);
+		cam_periph_lock(periph);
+		return (CAM_REQ_CMP_ERR);
+	}
 	disk_create(softc->disk, DISK_VERSION);
 	cam_periph_lock(periph);
 	cam_periph_unhold(periph);