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* cygthread.cc (cygthread::stub): Detect if thread function wants to release 

itself here, to avoid a race.
(cygthread::release): Clear more stuff.  Add a diagnostic for an internal
error.
* cygthread.h (auto_release): New function.
* pinfo.h (pinfo::remember): Add an argument to denote whether child is
detached.
* fork.cc (fork_parent): Reflect change in arguments to pinfo::remember.
* pinfo.cc (_pinfo::exit): Signal exit more forcibly.
(proc_waiter): Use cygthread::auto_release to signify that cygthread::stub
should release the thread.  This should avoid a race.
(pinfo::alert_parent): Don't signify an error when wr_proc_pipe == NULL.
* sigproc.cc (proc_subproc): Add support for PROC_DETACHED_CHILD.
* sigproc.h: Ditto.
* spawn.cc (spawn_guts): Specify whether child is detached or not when calling
pinfo::remember.
This commit is contained in:
Christopher Faylor 2004-12-23 14:57:08 +00:00
parent 3993374d4e
commit 4ee52924a6
9 changed files with 70 additions and 34 deletions
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20
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,23 @@
2004-12-23 Christopher Faylor <cgf@timesys.com>
* cygthread.cc (cygthread::stub): Detect if thread function wants to
release itself here, to avoid a race.
(cygthread::release): Clear more stuff. Add a diagnostic for an
internal error.
* cygthread.h (auto_release): New function.
* pinfo.h (pinfo::remember): Add an argument to denote whether child is
detached.
* fork.cc (fork_parent): Reflect change in arguments to
pinfo::remember.
* pinfo.cc (_pinfo::exit): Signal exit more forcibly.
(proc_waiter): Use cygthread::auto_release to signify that
cygthread::stub should release the thread. This should avoid a race.
(pinfo::alert_parent): Don't signify an error when wr_proc_pipe == NULL.
* sigproc.cc (proc_subproc): Add support for PROC_DETACHED_CHILD.
* sigproc.h: Ditto.
* spawn.cc (spawn_guts): Specify whether child is detached or not when
calling pinfo::remember.
2004-12-22 Christopher Faylor <cgf@timesys.com>
* cygheap.cc (cygheap_setup_for_child): Add api_fatal to catch failing

26
winsup/cygwin/cygthread.cc
View File

@ -69,13 +69,21 @@ cygthread::stub (VOID *arg)
info->func (info->arg == cygself ? info : info->arg);
/* ...so the above should always return */
/* If stack_ptr is NULL, the above function has set that to indicate
that it doesn't want to alert anyone with a SetEvent and should
just be marked as no longer inuse. Hopefully the function knows
that it is doing. */
if (!info->func)
info->release (false);
else
{
#ifdef DEBUGGING
info->func = NULL; // catch erroneous activation
info->__oldname = info->__name;
info->func = NULL; // catch erroneous activation
info->__oldname = info->__name;
#endif
info->__name = NULL;
if (info->inuse)
SetEvent (info->ev);
info->__name = NULL;
SetEvent (info->ev);
}
}
switch (WaitForSingleObject (info->thread_sync, INFINITE))
{
@ -231,7 +239,13 @@ cygthread::release (bool nuke_h)
__oldname = __name;
__name = NULL;
stack_ptr = NULL;
(void) InterlockedExchange (&inuse, 0); /* No longer in use */
func = NULL;
if (!InterlockedExchange (&inuse, 0))
#ifdef DEBUGGING
api_fatal ("released a thread that was not inuse");
#else
system_printf ("released a thread that was not inuse");
#endif
}
/* Forcibly terminate a thread. */

1
winsup/cygwin/cygthread.h
View File

@ -32,6 +32,7 @@ class cygthread
static DWORD WINAPI simplestub (VOID *);
static DWORD main_thread_id;
static const char * name (DWORD = 0);
void auto_release () {func = NULL;}
void release (bool);
cygthread (LPTHREAD_START_ROUTINE, LPVOID, const char *);
cygthread () {};

2
winsup/cygwin/fork.cc
View File

@ -413,7 +413,7 @@ fork_parent (HANDLE& hParent, dll *&first_dll,
it in afterwards. This requires more bookkeeping than I like, though,
so we'll just do it the easy way. So, terminate any child process if
we can't actually record the pid in the internal table. */
if (!child.remember ())
if (!child.remember (false))
{
TerminateProcess (pi.hProcess, 1);
set_errno (EAGAIN);

12
winsup/cygwin/pinfo.cc
View File

@ -135,8 +135,8 @@ _pinfo::exit (UINT n, bool norecord)
/* We could just let this happen automatically when the process
exits but this should gain us a microsecond or so by notifying
the parent early. */
if (wr_proc_pipe)
CloseHandle (wr_proc_pipe);
myself.alert_parent (0);
}
}
@ -764,7 +764,7 @@ proc_waiter (void *arg)
sigproc_printf ("exiting wait thread for pid %d", pid);
vchild.wait_thread = NULL;
_my_tls._ctinfo->release (false); /* return the cygthread to the cygthread pool */
_my_tls._ctinfo->auto_release (); /* automatically return the cygthread to the cygthread pool */
return 0;
}
@ -816,10 +816,10 @@ pinfo::alert_parent (char sig)
DWORD nb = 0;
/* Send something to our parent. If the parent has gone away,
close the pipe. */
if (myself->wr_proc_pipe == INVALID_HANDLE_VALUE)
if (myself->wr_proc_pipe == INVALID_HANDLE_VALUE
|| !myself->wr_proc_pipe)
/* no parent */;
else if (myself->wr_proc_pipe
&& WriteFile (myself->wr_proc_pipe, &sig, 1, &nb, NULL))
else if (WriteFile (myself->wr_proc_pipe, &sig, 1, &nb, NULL))
/* all is well */;
else if (GetLastError () != ERROR_BROKEN_PIPE)
debug_printf ("sending %d notification to parent failed, %E", sig);

5
winsup/cygwin/pinfo.h
View File

@ -168,9 +168,10 @@ public:
#ifndef _SIGPROC_H
int remember () {system_printf ("remember is not here"); return 0;}
#else
int remember ()
int remember (bool detach)
{
int res = proc_subproc (PROC_ADDCHILD, (DWORD) this);
int res = proc_subproc (detach ? PROC_DETACHED_CHILD : PROC_ADDCHILD,
(DWORD) this);
destroy = res ? false : true;
return res;
}

6
winsup/cygwin/sigproc.cc
View File

@ -38,8 +38,6 @@ details. */
#define WSSC 60000 // Wait for signal completion
#define WPSP 40000 // Wait for proc_subproc mutex
#define PSIZE 63 // Number of processes
#define no_signals_available() (!hwait_sig || (myself->sendsig == INVALID_HANDLE_VALUE) || exit_state)
#define NPROCS 256
@ -246,7 +244,9 @@ proc_subproc (DWORD what, DWORD val)
set_errno (EAGAIN);
break;
}
/* fall through intentionally */
case PROC_DETACHED_CHILD:
if (vchild != myself)
{
vchild->ppid = myself->pid;
@ -258,6 +258,8 @@ proc_subproc (DWORD what, DWORD val)
vchild->cygstarted = true;
vchild->process_state |= PID_INITIALIZING | (myself->process_state & PID_USETTY);
}
if (what == PROC_DETACHED_CHILD)
break;
procs[nprocs] = vchild;
rc = procs[nprocs].wait ();
if (rc)

10
winsup/cygwin/sigproc.h
View File

@ -30,11 +30,11 @@ enum
enum procstuff
{
PROC_ADDCHILD = 1, // add a new subprocess to list
PROC_CHILDTERMINATED = 2, // a child died
PROC_CLEARWAIT = 3, // clear all waits - signal arrived
PROC_WAIT = 4, // setup for wait() for subproc
PROC_NOTHING = 5 // nothing, really
PROC_ADDCHILD = 1, // add a new subprocess to list
PROC_DETACHED_CHILD = 2, // set up a detached child
PROC_CLEARWAIT = 3, // clear all waits - signal arrived
PROC_WAIT = 4, // setup for wait() for subproc
PROC_NOTHING = 5 // nothing, really
};
struct sigpacket

22
winsup/cygwin/spawn.cc
View File

@ -802,7 +802,7 @@ spawn_guts (const char * prog_arg, const char *const *argv,
this). */
if (!myself->wr_proc_pipe)
{
myself.remember ();
myself.remember (true);
wait_for_myself = true;
myself->wr_proc_pipe = INVALID_HANDLE_VALUE;
}
@ -822,14 +822,6 @@ spawn_guts (const char * prog_arg, const char *const *argv,
}
child->dwProcessId = pi.dwProcessId;
child.hProcess = pi.hProcess;
if (!child.remember ())
{
/* FIXME: Child in strange state now. */
CloseHandle (pi.hProcess);
CloseHandle (pi.hThread);
res = -1;
goto out;
}
strcpy (child->progname, real_path);
/* FIXME: This introduces an unreferenced, open handle into the child.
@ -839,9 +831,15 @@ spawn_guts (const char * prog_arg, const char *const *argv,
However, we should try to find another way to do this eventually. */
(void) DuplicateHandle (hMainProc, child.shared_handle (), pi.hProcess,
NULL, 0, 0, DUPLICATE_SAME_ACCESS);
if (mode == _P_DETACH)
myself.alert_parent (0);
child->start_time = time (NULL); /* Register child's starting time. */
if (!child.remember (mode == _P_DETACH))
{
/* FIXME: Child in strange state now */
CloseHandle (pi.hProcess);
ForceCloseHandle (pi.hThread);
res = -1;
goto out;
}
}
/* Start the child running */
@ -867,7 +865,7 @@ switch (mode)
res = -1;
break;
case _P_DETACH:
res = 0; /* Lose all memory of this child. */
res = 0; /* Lost all memory of this child. */
break;
case _P_NOWAIT:
case _P_NOWAITO: