Add SYSCTL ints for default normal I/O timeout && retry counts.

This is useful if you want to dynamically move into a Fibre Channel
or Multi-initiator environment that happens to be particularly noisy
and ugly that requires a lot of retries (with shorter I/O timeouts)
for commands destried by LIPs or Bus Resets.

Reviewed by:	deafening silence on audit && scsi on the retry counts
MFC after:	2 weeks

1 files changed, 20 insertions, 4 deletions

diff --git a/sys/cam/scsi/scsi_da.c b/sys/cam/scsi/scsi_da.c
index 5c705d5b1890..7301b1a46e63 100644
--- a/sys/cam/scsi/scsi_da.c
+++ b/sys/cam/scsi/scsi_da.c
@@ -38,6 +38,7 @@
 #include <sys/systm.h>
 #include <sys/kernel.h>
 #include <sys/bio.h>
+#include <sys/sysctl.h>
 #endif /* _KERNEL */
 
 #include <sys/devicestat.h>
@@ -277,6 +278,21 @@ static void		dashutdown(void *arg, int howto);
 #define DA_DEFAULT_TIMEOUT 60	/* Timeout in seconds */
 #endif
 
+#ifndef	DA_DEFAULT_RETRY
+#define	DA_DEFAULT_RETRY	4
+#endif
+
+static int da_retry_count = DA_DEFAULT_RETRY;
+static int da_default_timeout = DA_DEFAULT_TIMEOUT;
+
+SYSCTL_NODE(_kern, OID_AUTO, cam, CTLFLAG_RD, 0, "CAM Subsystem");
+SYSCTL_NODE(_kern_cam, OID_AUTO, da, CTLFLAG_RD, 0,
+            "CAM Direct Access Disk driver");
+SYSCTL_INT(_kern_cam_da, OID_AUTO, retry_count, CTLFLAG_RW,
+           &da_retry_count, 0, "Normal I/O retry count");
+SYSCTL_INT(_kern_cam_da, OID_AUTO, default_timeout, CTLFLAG_RW,
+           &da_default_timeout, 0, "Normal I/O timeout (in seconds)");
+
 /*
  * DA_ORDEREDTAG_INTERVAL determines how often, relative
  * to the default timeout, we check to see whether an ordered
@@ -802,7 +818,7 @@ dainit(void)
 	} else {
 
 		/*
-		 * Schedule a periodic event to occasioanly send an
+		 * Schedule a periodic event to occasionally send an
 		 * ordered tag to a device.
 		 */
 		timeout(dasendorderedtag, NULL,
@@ -1103,7 +1119,7 @@ dastart(struct cam_periph *periph, union ccb *start_ccb)
 				tag_code = MSG_SIMPLE_Q_TAG;
 			}
 			scsi_read_write(&start_ccb->csio,
-					/*retries*/4, /* retry a few times */
+					/*retries*/da_retry_count,
 					dadone,
 					tag_code,
 					bp->bio_cmd == BIO_READ,
@@ -1114,7 +1130,7 @@ dastart(struct cam_periph *periph, union ccb *start_ccb)
 					bp->bio_data,
 					bp->bio_bcount,
 					/*sense_len*/SSD_FULL_SIZE,
-					DA_DEFAULT_TIMEOUT * 1000);
+					da_default_timeout * 1000);
 			start_ccb->ccb_h.ccb_state = DA_CCB_BUFFER_IO;
 
 			/*
@@ -1535,7 +1551,7 @@ dasendorderedtag(void *arg)
 	}
 	/* Queue us up again */
 	timeout(dasendorderedtag, NULL,
-		(DA_DEFAULT_TIMEOUT * hz) / DA_ORDEREDTAG_INTERVAL);
+		(da_default_timeout * hz) / DA_ORDEREDTAG_INTERVAL);
 }
 
 /*