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authorPhilippe Waroquiers <philippe.waroquiers@skynet.be>2019-11-12 20:33:29 +0100
committerPhilippe Waroquiers <philippe.waroquiers@skynet.be>2019-11-14 02:25:39 +0100
commitbd454f8baf5382e6ad2869dc077e3d0711a17882 (patch)
tree3a8e03a789c62af55b429487cc2601b6a46a2ca4
parentAutomatic date update in version.in (diff)
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Fix python gdbpy_breakpoint_object leak.
valgrind reports a leak when a breakpoint is created then deleted: ==1313== 40 bytes in 1 blocks are definitely lost in loss record 1,115 of 8,596 ==1313== at 0x4835753: malloc (vg_replace_malloc.c:307) ==1313== by 0x6E05BC: _PyObject_New (object.c:255) ==1313== by 0x470E4B: gdbpy_breakpoint_created(breakpoint*) (py-breakpoint.c:1023) ==1313== by 0x2946D9: operator() (std_function.h:687) ==1313== by 0x2946D9: notify (observable.h:106) ==1313== by 0x2946D9: install_breakpoint(int, std::unique_ptr<breakpoint, std::default_delete<breakpoint> >&&, int) (breakpoint.c:8136) ==1313== by 0x295BCA: create_breakpoint_sal (breakpoint.c:8878) ==1313== by 0x295BCA: create_breakpoints_sal (breakpoint.c:8919) ==1313== by 0x295BCA: create_breakpoints_sal_default (breakpoint.c:13671) ... The leak is due to a superfluous Py_INCREF when the python object is allocated inside gdbpy_breakpoint_created, when the python object is allocated locally: this object has already a refcount of 1, and the only reference is the reference from the C breakpoint object. The Py_INCREF is however needed when the python object was created from python: the python object was stored in bppy_pending_object, and gdbpy_breakpoint_created creates a new reference to this object. Solve the leak by calling 'Py_INCREF (newbp);' only in the bppy_pending_object case. Regression tested on debian/amd64 natively and under valgrind on centos/amd64. Before the patch, 795 tests have a definite leak. After the patch, 197 have a definite leak. Thanks to Tom, that helped on irc with the python refcount logic. gdb/ChangeLog 2019-11-14 Philippe Waroquiers <philippe.waroquiers@skynet.be> * python/py-finishbreakpoint.c (gdbpy_breakpoint_created): only call Py_INCREF (newbp) in the bppy_pending_object case.
-rw-r--r--gdb/ChangeLog5
-rw-r--r--gdb/python/py-breakpoint.c2
2 files changed, 6 insertions, 1 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index be4c5a51f13..8be8efbb417 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2019-11-14 Philippe Waroquiers <philippe.waroquiers@skynet.be>
+
+ * python/py-finishbreakpoint.c (gdbpy_breakpoint_created):
+ only call Py_INCREF (newbp) in the bppy_pending_object case.
+
2019-11-13 Tom Tromey <tromey@adacore.com>
PR build/25182:
diff --git a/gdb/python/py-breakpoint.c b/gdb/python/py-breakpoint.c
index 65cb29fdca6..4170737416c 100644
--- a/gdb/python/py-breakpoint.c
+++ b/gdb/python/py-breakpoint.c
@@ -1017,6 +1017,7 @@ gdbpy_breakpoint_created (struct breakpoint *bp)
if (bppy_pending_object)
{
newbp = bppy_pending_object;
+ Py_INCREF (newbp);
bppy_pending_object = NULL;
}
else
@@ -1027,7 +1028,6 @@ gdbpy_breakpoint_created (struct breakpoint *bp)
newbp->bp = bp;
newbp->bp->py_bp_object = newbp;
newbp->is_finish_bp = 0;
- Py_INCREF (newbp);
++bppy_live;
}
else