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authorLudovic Courtès <ludo@gnu.org>2008-11-30 20:26:56 +0100
committerLudovic Courtès <ludo@gnu.org>2008-11-30 20:28:47 +0100
commita87c991545799b78d1a5a5a7f8419a458f01dfad (patch)
tree0f6fc90f1216bebbb403935f14d002ed988bb699
parent0328bf6a0e42c0c04908fb24c5f7d0c8d5133ea3 (diff)
downloadguile-a87c991545799b78d1a5a5a7f8419a458f01dfad.tar.gz
Fix potential deadlock in `make-struct'.
* libguile/struct.c (scm_make_struct): Remove critical section, as suggested by Linas Vepstas <linasvepstas@gmail.com>. See http://lists.gnu.org/archive/html/bug-guile/2008-11/msg00036.html for a discussion.
-rw-r--r--NEWS1
-rw-r--r--libguile/struct.c18
2 files changed, 9 insertions, 10 deletions
diff --git a/NEWS b/NEWS
index ee758f65e..6a0220e52 100644
--- a/NEWS
+++ b/NEWS
@@ -45,6 +45,7 @@ available: Guile is now always configured in "maintainer mode".
same thread
** The handler of SRFI-34 `with-exception-handler' is now invoked in the
dynamic environment of the call to `raise'
+** Fix potential deadlock in `make-struct'
Changes in 1.8.5 (since 1.8.4)
diff --git a/libguile/struct.c b/libguile/struct.c
index 6c84fce9a..1d93e5f15 100644
--- a/libguile/struct.c
+++ b/libguile/struct.c
@@ -449,8 +449,14 @@ SCM_DEFINE (scm_make_struct, "make-struct", 2, 0, 1,
if (! SCM_LAYOUT_TAILP (SCM_CHAR (last_char)))
goto bad_tail;
}
-
- SCM_CRITICAL_SECTION_START;
+
+ /* In guile 1.8.5 and earlier, everything below was covered by a
+ CRITICAL_SECTION lock. This can lead to deadlocks in garbage
+ collection, since other threads might be holding the heap_mutex, while
+ sleeping on the CRITICAL_SECTION lock. There does not seem to be any
+ need for a lock on the section below, as it does not access or update
+ any globals, so the critical section has been removed. */
+
if (SCM_STRUCT_DATA (vtable)[scm_struct_i_flags] & SCM_STRUCTF_ENTITY)
{
data = scm_alloc_struct (basic_size + tail_elts,
@@ -466,15 +472,7 @@ SCM_DEFINE (scm_make_struct, "make-struct", 2, 0, 1,
handle = scm_double_cell ((((scm_t_bits) SCM_STRUCT_DATA (vtable))
+ scm_tc3_struct),
(scm_t_bits) data, 0, 0);
- SCM_CRITICAL_SECTION_END;
- /* In guile 1.8.1 and earlier, the SCM_CRITICAL_SECTION_END above covered
- also the following scm_struct_init. But that meant if scm_struct_init
- finds an invalid type for a "u" field then there's an error throw in a
- critical section, which results in an abort(). Not sure if we need any
- protection across scm_struct_init. The data array contains garbage at
- this point, but until we return it's not visible to anyone except
- `gc'. */
scm_struct_init (handle, layout, data, tail_elts, init);
return handle;