14198 stack overflow from promisc callbacks

Reviewed by: Yuri Pankov <ypankov@tintri.com>
Reviewed by: Gordon Ross <Gordon.W.Ross@gmail.com>
Approved by: Dan McDonald <danmcd@joyent.com>

usr/src/uts/common/disp/thread_intr.c

@@ -23,10 +23,14 @@
  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
+/*
+ * Copyright 2015, Joyent, Inc.
+ */
 
 #include <sys/cpuvar.h>
 #include <sys/stack.h>
 #include <vm/seg_kp.h>
+#include <sys/machparam.h>
 #include <sys/proc.h>
 #include <sys/pset.h>
 #include <sys/sysmacros.h>
@@ -39,7 +43,7 @@ thread_create_intr(cpu_t *cp)
 {
 	kthread_t *tp;
 
-	tp = thread_create(NULL, 0,
+	tp = thread_create(NULL, LL_INTR_STKSZ,
 	    (void (*)())thread_create_intr, NULL, 0, &p0, TS_ONPROC, 0);
 
 	/*
@@ -85,9 +89,12 @@ thread_create_intr(cpu_t *cp)
 }
 
 /*
- * Allocate a given number of interrupt threads for a given CPU.
- * These threads will get freed by cpu_destroy_bound_threads()
- * when CPU gets unconfigured.
+ * Allocate a given number of interrupt threads for a given CPU.  These threads
+ * will get freed by cpu_destroy_bound_threads() when the CPU gets unconfigured.
+ *
+ * Note, high level interrupts are always serviced using cpu_intr_stack and are
+ * not allowed to block. Low level interrupts or soft-interrupts use the
+ * kthread_t's that we create through the calls to thread_create_intr().
  */
 void
 cpu_intr_alloc(cpu_t *cp, int n)

usr/src/uts/i86pc/sys/machparam.h

@@ -69,7 +69,7 @@ extern "C" {
  * The value defined below could grow to 16. hat structure and
  * page_t have room for 16 nodes.
  */
-#define	MAXNODES 	4
+#define	MAXNODES	4
 #define	NUMA_NODEMASK	0x0f
 
 /*
@@ -120,6 +120,18 @@ extern "C" {
 #define	DEFAULTSTKSZ	_MUL(DEFAULTSTKSZ_NPGS, PAGESIZE) /* as(1) lameness */
 #endif	/* !_ASM */
 
+/*
+ * Use a slightly larger thread stack size for interrupt threads rather than
+ * the default. This is useful for cases where the networking stack may do an
+ * rx and a tx in the context of a single interrupt and when combined with
+ * various promisc hooks that need memory, can cause us to get dangerously
+ * close to the edge of the traditional stack sizes. This is only a few pages
+ * more than a traditional stack and given that we don't have that many
+ * interrupt threads, the memory costs end up being more than worthwhile.
+ */
+#define	LL_INTR_STKSZ_NPGS	8
+#define	LL_INTR_STKSZ		(LL_INTR_STKSZ_NPGS * PAGESIZE)
+
 /*
  * During intial boot we limit heap to the top 4Gig.
  */