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* cygthread.cc (cygthread::release): Reset ev here if it exists. 

(cygthread::terminate_thread): Eliminat racy code which reset ev and
thread_sync.  Remove a few nonsensical inuse checks.  Exit at the bottom.
(cygthread::detach): Rewrite to again try to ensure that we don't say we're
signalled when we are not signalled.
* fhandler.cc (fhandler_base::raw_read): Revert to signalling read success
quickly.
* pipe.cc (fhandler_pipe::close): Use base method to close handle.
* sigproc.h (WAIT_SIG_PRIORITY): Just trundle along at normal priority to allow
the pipe thread to do its thing if possible.
* pinfo.h (pinfo::zap_cwd): Declare new function.
(pinfo::zap_cwd): Move 'cd out of the way code' here.
(pinfo::exit): Use it here.
* spawn.cc (spawn_guts): And here.
This commit is contained in:
Christopher Faylor 2005-02-11 15:24:15 +00:00
parent 199bf79367
commit cc9440b6f4
8 changed files with 168 additions and 66 deletions
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19
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,22 @@
2005-02-11 Christopher Faylor <cgf@timesys.com>
* cygthread.cc (cygthread::release): Reset ev here if it exists.
(cygthread::terminate_thread): Eliminat racy code which reset ev and
thread_sync. Remove a few nonsensical inuse checks. Exit at the
bottom.
(cygthread::detach): Rewrite to again try to ensure that we don't say
we're signalled when we are not signalled.
* fhandler.cc (fhandler_base::raw_read): Revert to signalling read
success quickly.
* pipe.cc (fhandler_pipe::close): Use base method to close handle.
* sigproc.h (WAIT_SIG_PRIORITY): Just trundle along at normal priority
to allow the pipe thread to do its thing if possible.
* pinfo.h (pinfo::zap_cwd): Declare new function.
(pinfo::zap_cwd): Move 'cd out of the way code' here.
(pinfo::exit): Use it here.
* spawn.cc (spawn_guts): And here.
2005-02-11 Corinna Vinschen <corinna@vinschen.de>
* times.cc (utimes): Open files with GENERIC_WRITE on file systems

169
winsup/cygwin/cygthread.cc
View File

@ -234,6 +234,8 @@ cygthread::release (bool nuke_h)
#endif
__name = NULL;
func = NULL;
if (ev)
ResetEvent (ev);
if (!InterlockedExchange (&inuse, 0))
#ifdef DEBUGGING
api_fatal ("released a thread that was not inuse");
@ -247,37 +249,22 @@ bool
cygthread::terminate_thread ()
{
bool terminated = true;
/* FIXME: The if (!inuse) stuff below should be handled better. The
problem is that terminate_thread could be called while a thread
is terminating and either the thread could be handling its own
release or, if this is being called during exit, some other
thread may be attempting to free up this resource. In the former
case, setting some kind of "I deal with my own exit" type of
flag may be the way to handle this. */
if (!is_freerange)
{
ResetEvent (*this);
ResetEvent (thread_sync);
}
debug_printf ("thread '%s', id %p, inuse %d, stack_ptr %p", name (), id, inuse, stack_ptr);
while (inuse && !stack_ptr)
low_priority_sleep (0);
if (!inuse)
return false;
goto force_notterminated;
(void) TerminateThread (h, 0);
(void) WaitForSingleObject (h, INFINITE);
if (ev)
terminated = WaitForSingleObject (ev, 0) != WAIT_OBJECT_0;
if (!inuse || exiting)
return false;
CloseHandle (h);
if (!inuse)
return false;
if (!inuse || exiting)
goto force_notterminated;
if (ev)
terminated = WaitForSingleObject (ev, 0) != WAIT_OBJECT_0;
MEMORY_BASIC_INFORMATION m;
memset (&m, 0, sizeof (m));
@ -289,8 +276,6 @@ cygthread::terminate_thread ()
debug_printf ("VirtualFree of allocation base %p<%p> failed, %E",
stack_ptr, m.AllocationBase);
if (!inuse)
/* nothing */;
if (is_freerange)
free (this);
else
@ -300,6 +285,12 @@ cygthread::terminate_thread ()
#endif
release (true);
}
goto out;
force_notterminated:
terminated = false;
out:
return terminated;
}
@ -311,7 +302,7 @@ bool
cygthread::detach (HANDLE sigwait)
{
bool signalled = false;
bool terminated = false;
bool thread_was_reset = false;
if (!inuse)
system_printf ("called detach but inuse %d, thread %p?", inuse, id);
else
@ -322,35 +313,61 @@ cygthread::detach (HANDLE sigwait)
res = WaitForSingleObject (*this, INFINITE);
else
{
/* Lower our priority and give priority to the read thread */
HANDLE hth = GetCurrentThread ();
LONG prio = GetThreadPriority (hth);
(void) ::SetThreadPriority (hth, THREAD_PRIORITY_IDLE);
HANDLE w4[2];
w4[0] = *this;
unsigned n = 2;
DWORD howlong = INFINITE;
w4[0] = sigwait;
w4[1] = signal_arrived;
res = WaitForSingleObject (sigwait, INFINITE);
if (res != WAIT_OBJECT_0)
system_printf ("WFSO sigwait %p failed, res %u, %E", sigwait, res);
res = WaitForMultipleObjects (2, w4, FALSE, INFINITE);
/* For a description of the below loop see the end of this file */
for (int i = 0; i < 2; i++)
switch (res = WaitForMultipleObjects (n, w4, FALSE, howlong))
{
case WAIT_OBJECT_0:
if (n == 1)
howlong = 50;
break;
case WAIT_OBJECT_0 + 1:
n = 1;
if (i--)
howlong = 50;
break;
case WAIT_TIMEOUT:
break;
default:
if (!exiting)
api_fatal ("WFMO failed waiting for cygthread '%s'", __name);
break;
}
/* WAIT_OBJECT_0 means that the thread successfully read something,
so wait for the cygthread to "terminate". */
if (res == WAIT_OBJECT_0)
signalled = false;
else if (res != WAIT_OBJECT_0 + 1)
api_fatal ("WFMO failed waiting for cygthread '%s'", __name);
else if ((res = WaitForSingleObject (*this, 0)) == WAIT_OBJECT_0)
signalled = false;
(void) WaitForSingleObject (*this, INFINITE);
else
{
terminated = true;
/* Thread didn't terminate on its own, so maybe we have to
do it. */
signalled = terminate_thread ();
/* Possibly the thread completed *just* before it was
terminated. Detect this. If this happened then the
read was not terminated on a signal. */
if (WaitForSingleObject (sigwait, 0) == WAIT_OBJECT_0)
signalled = false;
if (signalled)
set_sig_errno (EINTR);
thread_was_reset = true;
}
if (WaitForSingleObject (sigwait, 0) == WAIT_OBJECT_0)
signalled = false;
else if (signalled)
set_sig_errno (EINTR); /* caller should be dealing with return
values. */
(void) ::SetThreadPriority (hth, prio);
}
thread_printf ("%s returns %d, id %p", sigwait ? "WFMO" : "WFSO",
res, id);
if (terminated)
if (thread_was_reset)
/* already handled */;
else if (is_freerange)
{
@ -372,3 +389,71 @@ cygthread::terminate ()
{
exiting = 1;
}
/* The below is an explanation of synchronization loop in cygthread::detach.
The intent is that the loop will always try hard to wait for both
synchronization events from the reader thread but will exit with
res == WAIT_TIMEOUT if a signal occurred and the reader thread is
still blocked.
case 0 - no signal
i == 0 (howlong == INFINITE)
W0 activated
howlong not set because n != 1
just loop
i == 1 (howlong == INFINITE)
W0 activated
howlong not set because n != 1
just loop (to exit loop) - no signal
i == 2 (howlong == INFINITE)
exit loop
case 1 - signal before thread initialized
i == 0 (howlong == INFINITE)
WO + 1 activated
n set to 1
howlong untouched because i-- == 0
loop
i == 0 (howlong == INFINITE)
W0 must be activated
howlong set to 50 because n == 1
i == 1 (howlong == 50)
W0 activated
loop (to exit loop) - no signal
WAIT_TIMEOUT activated
signal potentially detected
loop (to exit loop)
i == 2 (howlong == 50)
exit loop
case 2 - signal after thread initialized
i == 0 (howlong == INFINITE)
W0 activated
howlong not set because n != 1
loop
i == 1 (howlong == INFINITE)
W0 + 1 activated
n set to 1
howlong set to 50 because i-- != 0
loop
i == 1 (howlong == 50)
W0 activated
loop (to exit loop) - no signal
WAIT_TIMEOUT activated
loop (to exit loop) - signal
i == 2 (howlong == 50)
exit loop
*/

10
winsup/cygwin/fhandler.cc
View File

@ -234,6 +234,11 @@ fhandler_base::raw_read (void *ptr, size_t& ulen)
signal_read_state (1);
}
BOOL res = ReadFile (get_handle (), ptr, len, (DWORD *) &ulen, 0);
if (read_state)
{
signal_read_state (1);
(void) SetThreadPriority (h, prio);
}
if (!res)
{
/* Some errors are not really errors. Detect such cases here. */
@ -270,11 +275,6 @@ fhandler_base::raw_read (void *ptr, size_t& ulen)
break;
}
}
if (read_state)
{
signal_read_state (1);
(void) SetThreadPriority (h, prio);
}
#undef bytes_read
}

16
winsup/cygwin/pinfo.cc
View File

@ -123,6 +123,16 @@ pinfo::maybe_set_exit_code_from_windows ()
self->pid, oexitcode, x, self->exitcode);
}
void
pinfo::zap_cwd ()
{
extern char windows_system_directory[];
/* Move to an innocuous location to avoid a race with other processes
that may want to manipulate the current directory before this
process has completely exited. */
(void) SetCurrentDirectory (windows_system_directory);
}
void
pinfo::exit (DWORD n)
{
@ -144,11 +154,7 @@ pinfo::exit (DWORD n)
if (n != EXITCODE_NOSET)
{
extern char windows_system_directory[];
/* Move to an innocuous location to avoid a race with other processes
that may want to manipulate the current directory before this
process has completely exited. */
(void) SetCurrentDirectory (windows_system_directory);
zap_cwd ();
self->alert_parent (0); /* Shave a little time by telling our
parent that we have now exited. */
}

3
winsup/cygwin/pinfo.h
View File

@ -196,7 +196,8 @@ public:
}
#endif
HANDLE shared_handle () {return h;}
void set_acl();
void set_acl ();
void zap_cwd ();
friend class _pinfo;
};

7
winsup/cygwin/pipe.cc
View File

@ -210,12 +210,7 @@ fhandler_pipe::close ()
if (read_state && !cygheap->fdtab.in_vfork_cleanup ())
#endif
ForceCloseHandle (read_state);
if (get_handle ())
{
CloseHandle (get_handle ());
set_io_handle (NULL);
}
return 0;
return fhandler_base::close ();
}
bool

2
winsup/cygwin/sigproc.h
View File

@ -88,7 +88,7 @@ extern char myself_nowait_dummy[];
extern struct sigaction *global_sigs;
#define WAIT_SIG_PRIORITY THREAD_PRIORITY_TIME_CRITICAL
#define WAIT_SIG_PRIORITY THREAD_PRIORITY_NORMAL
#define myself_nowait ((_pinfo *)myself_nowait_dummy)
#endif /*_SIGPROC_H*/

8
winsup/cygwin/spawn.cc
View File

@ -804,7 +804,7 @@ spawn_guts (const char * prog_arg, const char *const *argv,
If wr_proc_pipe exists, then it should be duplicated to the child.
If the child has exited already, that's ok. The parent will pick up
on this fact when we exit. dup_proc_pipe also closes our end of the pipe.
on this fact when we exit. dup_proc_pipe will close our end of the pipe.
Note that wr_proc_pipe may also be == INVALID_HANDLE_VALUE. That will make
dup_proc_pipe essentially a no-op. */
if (myself->wr_proc_pipe)
@ -812,11 +812,7 @@ spawn_guts (const char * prog_arg, const char *const *argv,
myself->sync_proc_pipe (); /* Make sure that we own wr_proc_pipe
just in case we've been previously
execed. */
SetCurrentDirectory ("c:\\"); /* Move to an innocuous location to
avoid races with other processes
that may want to manipulate the
current directory before this process
has completely exited. */
myself.zap_cwd ();
(void) myself->dup_proc_pipe (pi.hProcess);
}
}