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| author | Philippe Waroquiers <philippe.waroquiers@skynet.be> | 2019-11-12 20:33:29 +0100 |
|---|---|---|
| committer | Philippe Waroquiers <philippe.waroquiers@skynet.be> | 2019-11-14 02:25:39 +0100 |
| commit | bd454f8baf5382e6ad2869dc077e3d0711a17882 (patch) | |
| tree | 3a8e03a789c62af55b429487cc2601b6a46a2ca4 /gdb | |
| parent | 7a13ef8500d8d5e911739993c348ebeaaff550c5 (diff) | |
| download | gdb-bd454f8baf5382e6ad2869dc077e3d0711a17882.zip gdb-bd454f8baf5382e6ad2869dc077e3d0711a17882.tar.gz gdb-bd454f8baf5382e6ad2869dc077e3d0711a17882.tar.bz2 | |
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.
Diffstat (limited to 'gdb')
| -rw-r--r-- | gdb/ChangeLog | 5 | ||||
| -rw-r--r-- | gdb/python/py-breakpoint.c | 2 |
2 files changed, 6 insertions, 1 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog index be4c5a5..8be8efb 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 65cb29f..4170737 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 |