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Provide a sanity check during PyThreadState_DeleteCurrent() and

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PyThreadState_Delete() to avoid an infinite loop when the tstate list
is messed up and has somehow becomes circular and does not contain the
current thread.

I don't know how this happens but it does, *very* rarely.  On more than
one hardware platform.  I have not been able to reproduce it manually.

Attaching to a process where its happening: it has always been in an
infinite loop over a single element tstate list that is not the tstate
we're looking to delete.  It has been in t_bootstrap()'s call to
PyThreadState_DeleteCurrent() as a pthread is exiting.
This commit is contained in:
Gregory P. Smith 2008-01-21 07:11:11 +00:00
parent 21297fa621
commit 2778c999e3
1 changed files with 10 additions and 0 deletions
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10
Python/pystate.c
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@ -240,6 +240,7 @@ tstate_delete_common(PyThreadState *tstate)
{ {
PyInterpreterState *interp; PyInterpreterState *interp;
PyThreadState **p; PyThreadState **p;
PyThreadState *prev_p = NULL;
if (tstate == NULL) if (tstate == NULL)
Py_FatalError("PyThreadState_Delete: NULL tstate"); Py_FatalError("PyThreadState_Delete: NULL tstate");
interp = tstate->interp; interp = tstate->interp;
@ -252,6 +253,15 @@ tstate_delete_common(PyThreadState *tstate)
"PyThreadState_Delete: invalid tstate"); "PyThreadState_Delete: invalid tstate");
if (*p == tstate) if (*p == tstate)
break; break;
if (*p == prev_p)
Py_FatalError(
"PyThreadState_Delete: small circular list(!)"
" and tstate not found.");
prev_p = *p;
if ((*p)->next == interp->tstate_head)
Py_FatalError(
"PyThreadState_Delete: circular list(!) and"
" tstate not found.");
} }
*p = tstate->next; *p = tstate->next;
HEAD_UNLOCK(); HEAD_UNLOCK();