Add `hw.ciss.nop_message_heartbeat' tunable (default disabled) for

NOP-message polling in ciss_periodic().
Note that setting the tunable to non-zero can be workaround only for
`ADAPTER HEARTBEAT FAILED' problem, and may freeze the system w/o
the problem.

Reviewed by:	scottl
Reported by:	Attila Nagy
MFC after:	3 days

1 files changed, 4 insertions, 1 deletions

diff --git a/sys/dev/ciss/ciss.c b/sys/dev/ciss/ciss.c
index e33ff32..7369f8e 100644
--- a/sys/dev/ciss/ciss.c
+++ b/sys/dev/ciss/ciss.c
@@ -247,6 +247,9 @@ static struct cdevsw ciss_cdevsw = {
 static unsigned int ciss_expose_hidden_physical = 0;
 TUNABLE_INT("hw.ciss.expose_hidden_physical", &ciss_expose_hidden_physical);
 
+static unsigned int ciss_nop_message_heartbeat = 0;
+TUNABLE_INT("hw.ciss.nop_message_heartbeat", &ciss_nop_message_heartbeat);
+
 /************************************************************************
  * CISS adapters amazingly don't have a defined programming interface
  * value.  (One could say some very despairing things about PCI and
@@ -3099,7 +3102,7 @@ ciss_periodic(void *arg)
     /*
      * Send the NOP message and wait for a response.
      */
-    if ((error = ciss_get_request(sc, &cr)) == 0) {
+    if (ciss_nop_message_heartbeat != 0 && (error = ciss_get_request(sc, &cr)) == 0) {
 	cc = CISS_FIND_COMMAND(cr);
 	cr->cr_complete = ciss_nop_complete;
 	cc->cdb.cdb_length = 1;