Increase the number of caller memory storage slots from 2 or 4 to

MEMSTAT_MAXCALLER (8), and expose MEMSTAT_MAXCALLER via memstat.h so
that applications can check their assumptions about how many slots
are available.

Remove 'spare' memory storage in struct malloc_type, since we now
don't expose the data structure internals to applications and rely
on accessor methods, this approach to ABI stability isn't required.

MFC after:	7 days

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/libmemstat/memstat.h b/lib/libmemstat/memstat.h
index 847719c..5269a33 100644
--- a/lib/libmemstat/memstat.h
+++ b/lib/libmemstat/memstat.h
@@ -36,6 +36,14 @@
 #define	MEMSTAT_MAXCPU	16
 
 /*
+ * Amount of caller data to maintain for each caller data slot.  Applications
+ * must not request more than this number of caller save data, or risk
+ * corrupting internal libmemstat(3) data structures.  A compile time check
+ * in the application is probably appropriate.
+ */
+#define	MEMSTAT_MAXCALLER	8
+
+/*
  * libmemstat(3) is able to extract memory data from different allocators;
  * when it does so, it tags which allocator it got the data from so that
  * consumers can determine which fields are usable, as data returned varies