Add a loader tunable, kern.cam.ctl.disable, that will disable

loading CTL.  This may be useful in very low memory installations.

MFC after:	3 days

5 files changed, 33 insertions, 1 deletions

diff --git a/sys/cam/ctl/ctl.c b/sys/cam/ctl/ctl.c
index 957ed80..5b67b8f 100644
--- a/sys/cam/ctl/ctl.c
+++ b/sys/cam/ctl/ctl.c
@@ -308,7 +308,6 @@ static struct scsi_control_page control_page_changeable = {
 	/*aen_holdoff_period*/{0, 0}
 };
 
-SYSCTL_NODE(_kern_cam, OID_AUTO, ctl, CTLFLAG_RD, 0, "CAM Target Layer");
 
 /*
  * XXX KDM move these into the softc.
@@ -318,7 +317,12 @@ static int persis_offset;
 static uint8_t ctl_pause_rtr;
 static int     ctl_is_single;
 static int     index_to_aps_page;
+int	   ctl_disable = 0;
 
+SYSCTL_NODE(_kern_cam, OID_AUTO, ctl, CTLFLAG_RD, 0, "CAM Target Layer");
+SYSCTL_INT(_kern_cam_ctl, OID_AUTO, disable, CTLFLAG_RDTUN, &ctl_disable, 0,
+	   "Disable CTL");
+TUNABLE_INT("kern.cam.ctl.disable", &ctl_disable);
 
 /*
  * Serial number (0x80), device id (0x83), and supported pages (0x00)
@@ -949,6 +953,10 @@ ctl_init(void)
 	ctl_pause_rtr = 0;
         rcv_sync_msg = 0;
 
+	/* If we're disabled, don't initialize. */
+	if (ctl_disable != 0)
+		return;
+
 	control_softc = malloc(sizeof(*control_softc), M_DEVBUF, M_WAITOK);
 	softc = control_softc;
 
diff --git a/sys/cam/ctl/ctl_backend.c b/sys/cam/ctl/ctl_backend.c
index 5234c4a..863e9c7 100644
--- a/sys/cam/ctl/ctl_backend.c
+++ b/sys/cam/ctl/ctl_backend.c
@@ -62,6 +62,7 @@ __FBSDID("$FreeBSD$");
 #include <cam/ctl/ctl_debug.h>
 
 extern struct ctl_softc *control_softc;
+extern int ctl_disable;
 
 int
 ctl_backend_register(struct ctl_backend_driver *be)
@@ -71,6 +72,10 @@ ctl_backend_register(struct ctl_backend_driver *be)
 
 	ctl_softc = control_softc;
 
+	/* Don't continue if CTL is disabled */
+	if (ctl_disable != 0)
+		return (0);
+
 	mtx_lock(&ctl_softc->ctl_lock);
 	/*
 	 * Sanity check, make sure this isn't a duplicate registration.
diff --git a/sys/cam/ctl/ctl_frontend_cam_sim.c b/sys/cam/ctl/ctl_frontend_cam_sim.c
index 058c2c2..4a75202 100644
--- a/sys/cam/ctl/ctl_frontend_cam_sim.c
+++ b/sys/cam/ctl/ctl_frontend_cam_sim.c
@@ -119,6 +119,7 @@ struct cfcs_softc cfcs_softc;
  * amount of SCSI sense data that we will report to CAM.
  */
 static int cfcs_max_sense = sizeof(struct scsi_sense_data);
+extern int ctl_disable;
 
 SYSINIT(cfcs_init, SI_SUB_CONFIGURE, SI_ORDER_FOURTH, cfcs_init, NULL);
 SYSCTL_NODE(_kern_cam, OID_AUTO, ctl2cam, CTLFLAG_RD, 0,
@@ -138,6 +139,10 @@ cfcs_init(void)
 #endif
 	int retval;
 
+	/* Don't continue if CTL is disabled */
+	if (ctl_disable != 0)
+		return (0);
+
 	softc = &cfcs_softc;
 	retval = 0;
 	bzero(softc, sizeof(*softc));
diff --git a/sys/cam/ctl/ctl_frontend_internal.c b/sys/cam/ctl/ctl_frontend_internal.c
index 5231564..46f9f33 100644
--- a/sys/cam/ctl/ctl_frontend_internal.c
+++ b/sys/cam/ctl/ctl_frontend_internal.c
@@ -187,6 +187,7 @@ struct cfi_softc {
 MALLOC_DEFINE(M_CTL_CFI, "ctlcfi", "CTL CFI");
 
 static struct cfi_softc fetd_internal_softc;
+extern int ctl_disable;
 
 void cfi_init(void);
 void cfi_shutdown(void) __unused;
@@ -231,6 +232,10 @@ cfi_init(void)
 
 	retval = 0;
 
+	/* If we're disabled, don't initialize */
+	if (ctl_disable != 0)
+		return;
+
 	if (sizeof(struct cfi_lun_io) > CTL_PORT_PRIV_SIZE) {
 		printf("%s: size of struct cfi_lun_io %zd > "
 		       "CTL_PORT_PRIV_SIZE %d\n", __func__,
diff --git a/sys/cam/ctl/scsi_ctl.c b/sys/cam/ctl/scsi_ctl.c
index 044b9a9..ab51f01 100644
--- a/sys/cam/ctl/scsi_ctl.c
+++ b/sys/cam/ctl/scsi_ctl.c
@@ -227,12 +227,17 @@ static struct periph_driver ctlfe_driver =
 PERIPHDRIVER_DECLARE(ctl, ctlfe_driver);
 
 extern struct ctl_softc *control_softc;
+extern int ctl_disable;
 
 int
 ctlfeinitialize(void)
 {
 	cam_status status;
 
+	/* Don't initialize if we're disabled */
+	if (ctl_disable != 0)
+		return (0);
+
 	STAILQ_INIT(&ctlfe_softc_list);
 
 	mtx_init(&ctlfe_list_mtx, ctlfe_mtx_desc, NULL, MTX_DEF);
@@ -263,6 +268,10 @@ ctlfeinit(void)
 {
 	cam_status status;
 
+	/* Don't initialize if we're disabled */
+	if (ctl_disable != 0)
+		return;
+
 	STAILQ_INIT(&ctlfe_softc_list);
 
 	mtx_init(&ctlfe_list_mtx, ctlfe_mtx_desc, NULL, MTX_DEF);