[PATCH 5/6] Add catch-all alloc retry probe.

[Alexandre Oliva <aoliva at redhat dot com>]

for ChangeLog

	* malloc/arena.c (arena_get_retry): Add memory_arena_retry probe.
	* manual/probes.texi: Document it.
---
 malloc/arena.c     |    1 +
 manual/probes.texi |   12 ++++++++++++
 2 files changed, 13 insertions(+)

diff --git a/malloc/arena.c b/malloc/arena.c
index 89e8b92..9ace186 100644
--- a/malloc/arena.c
+++ b/malloc/arena.c
@@ -932,6 +932,7 @@ arena_get2(mstate a_tsd, size_t size, mstate avoid_arena)
 static mstate
 arena_get_retry (mstate ar_ptr, size_t bytes)
 {
+  LIBC_PROBE (memory_arena_retry, 2, bytes, ar_ptr);
   if(ar_ptr != &main_arena) {
     (void)mutex_unlock(&ar_ptr->mutex);
     ar_ptr = &main_arena;
diff --git a/manual/probes.texi b/manual/probes.texi
index 50e0fc2..fdf41c2 100644
--- a/manual/probes.texi
+++ b/manual/probes.texi
@@ -48,6 +48,18 @@ corresponding two-argument functions, so that in all of these probes the
 user-requested allocation size is in @var{$arg1}.
 @end deftp
 
+@deftp Probe memory_arena_retry (size_t @var{$arg1}, void *@var{$arg2})
+This probe is triggered within @code{arena_get_retry} (the function
+called to select the alternate arena in which to retry an allocation
+that failed on the first attempt), before the selection takes place.
+This probe is redundant, but much easier to use when it's not important
+to determine which of the various memory allocation functions is failing
+to allocate on the first try.  Argument @var{$arg1} is the same as in
+the function-specific probes, except for extra room for padding
+introduced by functions that have to ensure stricter alignment.
+Argument @var{$arg2} is the arena in which allocation failed.
+@end deftp
+
 @deftp Probe memory_arena_new (void *@var{$arg1}, size_t @var{$arg2})
 This probe is triggered when @code{malloc} allocates and initializes an
 additional arena (not the main arena), but before the arena is assigned