1 files changed, 85 insertions, 3 deletions

diff --git a/usr/src/cmd/mdb/common/modules/genunix/combined.c b/usr/src/cmd/mdb/common/modules/genunix/combined.c
index 412761a7bd..be529ae40a 100644
--- a/usr/src/cmd/mdb/common/modules/genunix/combined.c
+++ b/usr/src/cmd/mdb/common/modules/genunix/combined.c
@@ -23,8 +23,6 @@
  * Use is subject to license terms.
  */
 
-#pragma ident	"%Z%%M%	%I%	%E% SMI"
-
 #include <mdb/mdb_modapi.h>
 
 typedef struct combined_walk {
@@ -40,6 +38,10 @@ typedef struct combined_walk_data {
 	uintptr_t cwd_initial_walk_addr;	/* to init each walk */
 	combined_walk_t *cwd_current_walk;
 	combined_walk_t *cwd_final_walk;	/* tail pointer */
+
+	struct combined_walk_data *cwd_next;
+	struct combined_walk_data *cwd_prev;
+	void *cwd_tag;				/* used to find this data */
 } combined_walk_data_t;
 
 /*
@@ -59,9 +61,68 @@ combined_walk_init(mdb_walk_state_t *wsp)
 
 	cwd->cwd_initial_walk_addr = wsp->walk_addr;
 	cwd->cwd_current_walk = cwd->cwd_final_walk = NULL;
+	cwd->cwd_next = cwd->cwd_prev = NULL;
+	cwd->cwd_tag = NULL;
 	wsp->walk_data = cwd;
 }
 
+/*
+ * If a sub-walker's walk_step() is interrupted (by Ctrl-C or entering 'q' when
+ * prompted for the next screenful of data), there won't be an opportunity to
+ * switch wsp->walk_data from the sub-walker's data back to the combined walk
+ * data, since control will not return from walk_step(). Since mdb is
+ * single-threaded, we can save the combined walk data for combined_walk_fini()
+ * to use in case it was reached from an interrupted walk_step(). To allow for
+ * the possibility of nested combined walks, we'll save them on a list tagged by
+ * the sub-walker's data.
+ */
+static combined_walk_data_t *cwd_saved;
+
+static void
+combined_walk_data_save(combined_walk_data_t *cwd, void *tag)
+{
+	cwd->cwd_next = cwd_saved;
+	cwd->cwd_prev = NULL;
+	if (cwd_saved != NULL) {
+		cwd_saved->cwd_prev = cwd;
+	}
+	cwd_saved = cwd;
+	cwd->cwd_tag = tag;
+}
+
+static void
+combined_walk_data_drop(combined_walk_data_t *cwd)
+{
+	if (cwd->cwd_prev == NULL) {
+		cwd_saved = cwd->cwd_next;
+	} else {
+		cwd->cwd_prev->cwd_next = cwd->cwd_next;
+	}
+	if (cwd->cwd_next != NULL) {
+		cwd->cwd_next->cwd_prev = cwd->cwd_prev;
+	}
+	cwd->cwd_next = cwd->cwd_prev = NULL;
+	cwd->cwd_tag = NULL;
+}
+
+static combined_walk_data_t *
+combined_walk_data_find(void *tag)
+{
+	combined_walk_data_t *cwd;
+
+	if (tag == NULL) {
+		return (NULL);
+	}
+
+	for (cwd = cwd_saved; cwd != NULL; cwd = cwd->cwd_next) {
+		if (cwd->cwd_tag == tag) {
+			return (cwd);
+		}
+	}
+
+	return (NULL);
+}
+
 static void
 combined_walk_append(combined_walk_data_t *cwd, combined_walk_t *cw)
 {
@@ -133,7 +194,11 @@ combined_walk_step(mdb_walk_state_t *wsp)
 		}
 	}
 
+	/* save cwd for fini() in case step() is interrupted */
+	combined_walk_data_save(cwd, cw->cw_data);
 	status = cw->cw_step(wsp);
+	/* control may never reach here */
+	combined_walk_data_drop(cwd);
 
 	if (status == WALK_DONE) {
 		(void) combined_walk_remove_current(cwd);
@@ -150,9 +215,26 @@ combined_walk_step(mdb_walk_state_t *wsp)
 void
 combined_walk_fini(mdb_walk_state_t *wsp)
 {
-	combined_walk_data_t *cwd = wsp->walk_data;
+	combined_walk_data_t *cwd;
 	combined_walk_t *cw;
 
+	/*
+	 * If walk_step() was interrupted, wsp->walk_data will be the
+	 * sub-walker's data, not the combined walker's data, so first check to
+	 * see if there is saved combined walk data tagged by the presumed
+	 * sub-walker's walk data.
+	 */
+	cwd = combined_walk_data_find(wsp->walk_data);
+	if (cwd == NULL) {
+		/*
+		 * walk_step() was not interrupted, so wsp->walk_data is
+		 * actually the combined walk data.
+		 */
+		cwd = wsp->walk_data;
+	} else {
+		combined_walk_data_drop(cwd);
+	}
+
 	while ((cw = combined_walk_remove_current(cwd)) != NULL) {
 		if (cw->cw_initialized) {
 			wsp->walk_data = cw->cw_data;