JehanneOS/newlib
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

* cygheap.cc (init_cygheap::init_tls_list): Accommodate threadlist

Browse Source 
having a new type threadlist_t *.  Convert commented out code into an
	#if 0.  Create thread mutex.  Explain why.
	(init_cygheap::remove_tls): Drop timeout value.  Always wait infinitely
	for tls_sentry.  Return mutex HANDLE of just deleted threadlist entry.
	(init_cygheap::find_tls): New implementation taking tls pointer as
	search parameter.  Return threadlist_t *.
	(init_cygheap::find_tls): Return threadlist_t *.  Define ix as auto
	variable.  Drop exception handling since crash must be made impossible
	due to correct synchronization.  Return with locked mutex.
	* cygheap.h (struct threadlist_t): Define.
	(struct init_cygheap): Convert threadlist to threadlist_t type.
	(init_cygheap::remove_tls): Align declaration to above change.
	(init_cygheap::find_tls): Ditto.
	(init_cygheap::unlock_tls): Define.
	* cygtls.cc (_cygtls::remove): Unlock and close mutex when finishing.
	* exceptions.cc (sigpacket::process): Lock _cygtls area of thread before
	accessing it.
	* fhandler_termios.cc (fhandler_termios::bg_check): Ditto.
	* sigproc.cc (sig_send): Ditto.
	* thread.cc (pthread::exit): Ditto.  Add comment.
	(pthread::cancel): Ditto.
This commit is contained in:
Corinna Vinschen
2014-11-28 20:46:13 +00:00
parent c2f50c4099
commit 26158dc3e9
8 changed files with 200 additions and 67 deletions
Download Patch File Download Diff File Expand all files Collapse all files

119
winsup/cygwin/cygheap.cc
View File

@ -617,8 +617,9 @@ init_cygheap::init_tls_list ()
else
{
sthreads = THREADLIST_CHUNK;
threadlist = (_cygtls **) ccalloc_abort (HEAP_TLS, cygheap->sthreads,
sizeof (cygheap->threadlist[0]));
threadlist = (threadlist_t *)
ccalloc_abort (HEAP_TLS, cygheap->sthreads,
sizeof (cygheap->threadlist[0]));
}
tls_sentry::lock.init ("thread_tls_sentry");
}
@ -630,72 +631,116 @@ init_cygheap::add_tls (_cygtls *t)
tls_sentry here (INFINITE);
if (nthreads >= cygheap->sthreads)
{
threadlist = (_cygtls **)
threadlist = (threadlist_t *)
crealloc_abort (threadlist, (sthreads += THREADLIST_CHUNK)
* sizeof (threadlist[0]));
// memset (threadlist + nthreads, 0, THREADLIST_CHUNK * sizeof (threadlist[0]));
#if 0
memset (threadlist + nthreads, 0,
THREADLIST_CHUNK * sizeof (threadlist[0]));
#endif
}
threadlist[nthreads++] = t;
/* Create a mutex to lock the thread's _cygtls area. This is required for
the following reason: The thread's _cygtls area is on the thread's
own stack. Thus, when the thread exits, its _cygtls area is automatically
destroyed by the OS. Thus, when this happens while the signal thread
still utilizes the thread's _cygtls area, things go awry.
The following methods take this into account:
- The thread mutex is generally only locked under tls_sentry locking.
- remove_tls, called from _cygtls::remove, locks the mutex before
removing the threadlist entry and _cygtls::remove then unlocks and
destroyes the mutex.
- find_tls, called from several places but especially from the signal
thread, will lock the mutex on exit and the caller can access the
_cygtls area locked. Always make sure to unlock the mutex when the
_cygtls area isn't needed anymore. */
threadlist[nthreads].thread = t;
threadlist[nthreads].mutex = CreateMutexW (&sec_none_nih, FALSE, NULL);
if (!threadlist[nthreads].mutex)
api_fatal ("Can't create per-thread mutex, %E");
++nthreads;
}
void
init_cygheap::remove_tls (_cygtls *t, DWORD wait)
HANDLE __reg3
init_cygheap::remove_tls (_cygtls *t)
{
tls_sentry here (wait);
HANDLE mutex = NULL;
tls_sentry here (INFINITE);
if (here.acquired ())
{
for (uint32_t i = 0; i < nthreads; i++)
if (t == threadlist[i])
if (t == threadlist[i].thread)
{
mutex = threadlist[i].mutex;
WaitForSingleObject (mutex, INFINITE);
if (i < --nthreads)
threadlist[i] = threadlist[nthreads];
debug_only_printf ("removed %p element %u", this, i);
break;
}
}
/* Leave with locked mutex. The calling function is responsible for
unlocking the mutex. */
return mutex;
}
_cygtls __reg3 *
threadlist_t __reg2 *
init_cygheap::find_tls (_cygtls *tls)
{
tls_sentry here (INFINITE);
threadlist_t *t = NULL;
int ix = -1;
while (++ix < (int) nthreads)
{
if (!threadlist[ix].thread->tid
|| !threadlist[ix].thread->initialized)
;
if (threadlist[ix].thread == tls)
{
t = &threadlist[ix];
break;
}
}
/* Leave with locked mutex. The calling function is responsible for
unlocking the mutex. */
if (t)
WaitForSingleObject (t->mutex, INFINITE);
return t;
}
threadlist_t __reg3 *
init_cygheap::find_tls (int sig, bool& issig_wait)
{
debug_printf ("sig %d\n", sig);
tls_sentry here (INFINITE);
static int NO_COPY ix;
_cygtls *t = NULL;
threadlist_t *t = NULL;
issig_wait = false;
ix = -1;
int ix = -1;
/* Scan thread list looking for valid signal-delivery candidates */
while (++ix < (int) nthreads)
{
__try
/* Only pthreads have tid set to non-0. */
if (!threadlist[ix].thread->tid
|| !threadlist[ix].thread->initialized)
;
else if (sigismember (&(threadlist[ix].thread->sigwait_mask), sig))
{
/* Only pthreads have tid set to non-0. */
if (!threadlist[ix]->tid)
continue;
else if (sigismember (&(threadlist[ix]->sigwait_mask), sig))
{
t = cygheap->threadlist[ix];
issig_wait = true;
__leave;
}
else if (!t && !sigismember (&(threadlist[ix]->sigmask), sig))
t = cygheap->threadlist[ix];
t = &cygheap->threadlist[ix];
issig_wait = true;
break;
}
__except (NO_ERROR)
{
/* We're here because threadlist[ix] became NULL or invalid. In
theory this should be impossible due to correct synchronization.
But *if* it happens, just remove threadlist[ix] from threadlist.
TODO: This should be totally unnecessary. */
debug_printf ("cygtls synchronization is leaking...");
remove_tls (threadlist[ix], 0);
--ix;
}
__endtry
else if (!t && !sigismember (&(threadlist[ix].thread->sigmask), sig))
t = &cygheap->threadlist[ix];
}
/* Leave with locked mutex. The calling function is responsible for
unlocking the mutex. */
if (t)
WaitForSingleObject (t->mutex, INFINITE);
return t;
}