[PATCH v3 0/3] Three fixes for signal handling
Takashi Yano (3): Cygwin: signal: Fix deadlock on SIGCONT Cygwin: signal: Fix a race issue on modifying _pinfo::process_state Cygwin: signal: Fix a problem that process hangs on exit [<= revised] winsup/cygwin/exceptions.cc | 31 winsup/cygwin/fork.cc| 5 +++-- winsup/cygwin/local_includes/pinfo.h | 4 ++-- winsup/cygwin/pinfo.cc | 11 +- winsup/cygwin/signal.cc | 6 -- winsup/cygwin/sigproc.cc | 2 +- winsup/cygwin/spawn.cc | 6 +++--- 7 files changed, 37 insertions(+), 28 deletions(-) -- 2.45.1
[PATCH v3 3/3] Cygwin: signal: Fix a problem that process hangs on exit
The process that receives many SIGSTOP/SIGCONT signals sometimes hangs
on exit in sig_dispatch_pending(). This patch skips processing signals
in call_signal_handler() when exit_state > ES_EXIT_STARTING to avoid
that situation.
Addresses: https://cygwin.com/pipermail/cygwin/2025-February/257473.html
Fixes: d243e51ef1d3 ("Cygwin: signal: Fix deadlock between main thread and sig
thread")
Reported-by: Christian Franke
Reviewed-by:
Signed-off-by: Takashi Yano
---
winsup/cygwin/exceptions.cc | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index 45c71cbdf..759f89dca 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -1675,7 +1675,7 @@ _cygtls::call_signal_handler ()
while (1)
{
lock ();
- if (!current_sig)
+ if (!current_sig || exit_state > ES_EXIT_STARTING)
{
unlock ();
break;
--
2.45.1
[PATCH v3 1/3] Cygwin: signal: Fix deadlock on SIGCONT
If SIGCONT starts processing while __SIGFLUSHFAST is ongoing,
_main_tls->current_sig will never be cleared because the signal
processing is stopped while waiting for the wake-up event in the
main thread. This leads to a deadlock in the while loop waiting for
current_sig to be cleared. With this patch, the function returns to
wait_sig() if current_sig is set, rather than waiting for it in the
while loop.
Addresses: https://cygwin.com/pipermail/cygwin/2025-February/257473.html
Fixes: 9d2155089e87 ("(sigpacket::process): Call handle_SIGCONT early to deal
with SIGCONT.")
Reported-by: Christian Franke
Reviewed-by:
Signed-off-by: Takashi Yano
---
winsup/cygwin/exceptions.cc | 25 +++--
1 file changed, 15 insertions(+), 10 deletions(-)
diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index f576c5ff2..c6e82b6c5 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -1425,23 +1425,18 @@ _cygtls::handle_SIGCONT ()
if (NOTSTATE (myself, PID_STOPPED))
return;
- myself->stopsig = 0;
- myself->process_state &= ~PID_STOPPED;
- /* Carefully tell sig_handle_tty_stop to wake up.
- Make sure that any pending signal is handled before trying to
- send a new one. Then make sure that SIGCONT has been recognized
- before exiting the loop. */
- while (current_sig) /* Assume that it's ok to just test sig outside of a */
-yield (); /* lock since setup_handler does it this way. */
-
lock ();
current_sig = SIGCONT;
set_signal_arrived (); /* alert sig_handle_tty_stop */
unlock ();
+ /* Make sure that SIGCONT has been recognized before exiting the loop. */
while (current_sig == SIGCONT)
yield ();
+ myself->stopsig = 0;
+ myself->process_state &= ~PID_STOPPED;
+
/* Clear pending stop signals */
sig_clear (SIGSTOP, false);
sig_clear (SIGTSTP, false);
@@ -1473,7 +1468,17 @@ sigpacket::process ()
myself->rusage_self.ru_nsignals++;
if (si.si_signo == SIGCONT)
-_main_tls->handle_SIGCONT ();
+{
+ /* Carefully tell sig_handle_tty_stop to wake up.
+Make sure that any pending signal is handled before trying to
+send a new one. */
+ if (_main_tls->current_sig)
+ {
+ rc = -1;
+ goto done;
+ }
+ _main_tls->handle_SIGCONT ();
+}
/* SIGKILL is special. It always goes through. */
if (si.si_signo == SIGKILL)
--
2.45.1
[PATCH v3 2/3] Cygwin: signal: Fix a race issue on modifying _pinfo::process_state
The PID_STOPPED flag in _ponfo::process_state is sometimes accidentally
cleared due to a race condition when modifying it with the "|=" or "&="
operators. This patch uses InterlockedOr/And() instead to avoid the
race condition.
Addresses: https://cygwin.com/pipermail/cygwin/2025-February/257473.html
Fixes: 1fd5e000ace55 ("import winsup-2000-02-17 snapshot")
Reported-by: Christian Franke
Reviewed-by:
Signed-off-by: Takashi Yano
---
winsup/cygwin/exceptions.cc | 6 +++---
winsup/cygwin/fork.cc| 5 +++--
winsup/cygwin/local_includes/pinfo.h | 4 ++--
winsup/cygwin/pinfo.cc | 11 ++-
winsup/cygwin/signal.cc | 6 --
winsup/cygwin/sigproc.cc | 2 +-
winsup/cygwin/spawn.cc | 6 +++---
7 files changed, 22 insertions(+), 18 deletions(-)
diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index c6e82b6c5..45c71cbdf 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -882,7 +882,7 @@ sig_handle_tty_stop (int sig, siginfo_t *, void *)
/* Silently ignore attempts to suspend if there is no accommodating
cygwin parent to deal with this behavior. */
if (!myself->cygstarted)
-myself->process_state &= ~PID_STOPPED;
+InterlockedAnd ((LONG *) &myself->process_state, ~PID_STOPPED);
else
{
_my_tls.incyg = 1;
@@ -948,7 +948,7 @@ _cygtls::interrupt_setup (siginfo_t& si, void *handler,
struct sigaction& siga)
if (handler == sig_handle_tty_stop)
{
myself->stopsig = 0;
- myself->process_state |= PID_STOPPED;
+ InterlockedOr ((LONG *) &myself->process_state, PID_STOPPED);
}
infodata = si;
@@ -1435,7 +1435,7 @@ _cygtls::handle_SIGCONT ()
yield ();
myself->stopsig = 0;
- myself->process_state &= ~PID_STOPPED;
+ InterlockedAnd ((LONG *) &myself->process_state, ~PID_STOPPED);
/* Clear pending stop signals */
sig_clear (SIGSTOP, false);
diff --git a/winsup/cygwin/fork.cc b/winsup/cygwin/fork.cc
index 41a533705..783971b76 100644
--- a/winsup/cygwin/fork.cc
+++ b/winsup/cygwin/fork.cc
@@ -678,8 +678,9 @@ dofork (void **proc, bool *with_forkables)
if (ischild)
{
- myself->process_state |= PID_ACTIVE;
- myself->process_state &= ~(PID_INITIALIZING | PID_EXITED | PID_REAPED);
+ InterlockedOr ((LONG *) &myself->process_state, PID_ACTIVE);
+ InterlockedAnd ((LONG *) &myself->process_state,
+ ~(PID_INITIALIZING | PID_EXITED | PID_REAPED));
}
else if (res < 0)
{
diff --git a/winsup/cygwin/local_includes/pinfo.h
b/winsup/cygwin/local_includes/pinfo.h
index 4de0f80dd..3086f9941 100644
--- a/winsup/cygwin/local_includes/pinfo.h
+++ b/winsup/cygwin/local_includes/pinfo.h
@@ -271,9 +271,9 @@ public:
push_process_state (int add_flag)
{
flag = add_flag;
-myself->process_state |= flag;
+InterlockedOr ((LONG *) &myself->process_state, flag);
}
- void pop () { myself->process_state &= ~(flag); }
+ void pop () { InterlockedAnd ((LONG *) &myself->process_state, ~(flag)); }
~push_process_state () { pop (); }
};
diff --git a/winsup/cygwin/pinfo.cc b/winsup/cygwin/pinfo.cc
index 1f26a3ccd..c69213f9a 100644
--- a/winsup/cygwin/pinfo.cc
+++ b/winsup/cygwin/pinfo.cc
@@ -69,7 +69,7 @@ pinfo::thisproc (HANDLE h)
child_info_spawn::handle_spawn. */
init (cygheap->pid, flags, h);
- procinfo->process_state |= PID_IN_USE;
+ InterlockedOr ((LONG *) &procinfo->process_state, PID_IN_USE);
procinfo->dwProcessId = myself_initial.dwProcessId;
procinfo->sendsig = myself_initial.sendsig;
wcscpy (procinfo->progname, myself_initial.progname);
@@ -89,7 +89,7 @@ pinfo_init (char **envp, int envc)
{
environ_init (envp, envc);
/* spawn has already set up a pid structure for us so we'll use that */
- myself->process_state |= PID_CYGPARENT;
+ InterlockedOr ((LONG *) &myself->process_state, PID_CYGPARENT);
}
else
{
@@ -108,10 +108,11 @@ pinfo_init (char **envp, int envc)
debug_printf ("Set nice to %d", myself->nice);
}
- myself->process_state |= PID_ACTIVE;
- myself->process_state &= ~(PID_INITIALIZING | PID_EXITED | PID_REAPED);
+ InterlockedOr ((LONG *) &myself->process_state, PID_ACTIVE);
+ InterlockedAnd ((LONG *) &myself->process_state,
+ ~(PID_INITIALIZING | PID_EXITED | PID_REAPED));
if (being_debugged ())
-myself->process_state |= PID_DEBUGGED;
+InterlockedOr ((LONG *) &myself->process_state, PID_DEBUGGED);
myself.preserve ();
debug_printf ("pid %d, pgid %d, process_state %y",
myself->pid, myself->pgid, myself->process_state);
diff --git a/winsup/cygwin/signal.cc b/winsup/cygwin/signal.cc
index 0bd64963f..f8ba67e75 100644
--- a/winsup/cygwin/signal.cc
+++ b/winsup/cygwin/signal.cc
@@ -456,9 +456,11 @@ sigaction_worker (int sig, const struct sigaction *newact,
sig_clear (sig, true);
if (sig == SIGCHL
[PATCH v2 2/3] Cygwin: signal: Fix a race issue on modifying _pinfo::process_state
The PID_STOPPED flag in _ponfo::process_state is sometimes accidentally
cleared due to a race condition when modifying it with the "|=" or "&="
operators. This patch uses InterlockedOr/And() instead to avoid the
race condition.
Addresses: https://cygwin.com/pipermail/cygwin/2025-February/257473.html
Fixes: 1fd5e000ace55 ("import winsup-2000-02-17 snapshot")
Reported-by: Christian Franke
Reviewed-by:
Signed-off-by: Takashi Yano
---
winsup/cygwin/exceptions.cc | 6 +++---
winsup/cygwin/fork.cc| 5 +++--
winsup/cygwin/local_includes/pinfo.h | 4 ++--
winsup/cygwin/pinfo.cc | 11 ++-
winsup/cygwin/signal.cc | 6 --
winsup/cygwin/sigproc.cc | 2 +-
winsup/cygwin/spawn.cc | 6 +++---
7 files changed, 22 insertions(+), 18 deletions(-)
diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index c6e82b6c5..45c71cbdf 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -882,7 +882,7 @@ sig_handle_tty_stop (int sig, siginfo_t *, void *)
/* Silently ignore attempts to suspend if there is no accommodating
cygwin parent to deal with this behavior. */
if (!myself->cygstarted)
-myself->process_state &= ~PID_STOPPED;
+InterlockedAnd ((LONG *) &myself->process_state, ~PID_STOPPED);
else
{
_my_tls.incyg = 1;
@@ -948,7 +948,7 @@ _cygtls::interrupt_setup (siginfo_t& si, void *handler,
struct sigaction& siga)
if (handler == sig_handle_tty_stop)
{
myself->stopsig = 0;
- myself->process_state |= PID_STOPPED;
+ InterlockedOr ((LONG *) &myself->process_state, PID_STOPPED);
}
infodata = si;
@@ -1435,7 +1435,7 @@ _cygtls::handle_SIGCONT ()
yield ();
myself->stopsig = 0;
- myself->process_state &= ~PID_STOPPED;
+ InterlockedAnd ((LONG *) &myself->process_state, ~PID_STOPPED);
/* Clear pending stop signals */
sig_clear (SIGSTOP, false);
diff --git a/winsup/cygwin/fork.cc b/winsup/cygwin/fork.cc
index 41a533705..783971b76 100644
--- a/winsup/cygwin/fork.cc
+++ b/winsup/cygwin/fork.cc
@@ -678,8 +678,9 @@ dofork (void **proc, bool *with_forkables)
if (ischild)
{
- myself->process_state |= PID_ACTIVE;
- myself->process_state &= ~(PID_INITIALIZING | PID_EXITED | PID_REAPED);
+ InterlockedOr ((LONG *) &myself->process_state, PID_ACTIVE);
+ InterlockedAnd ((LONG *) &myself->process_state,
+ ~(PID_INITIALIZING | PID_EXITED | PID_REAPED));
}
else if (res < 0)
{
diff --git a/winsup/cygwin/local_includes/pinfo.h
b/winsup/cygwin/local_includes/pinfo.h
index 4de0f80dd..3086f9941 100644
--- a/winsup/cygwin/local_includes/pinfo.h
+++ b/winsup/cygwin/local_includes/pinfo.h
@@ -271,9 +271,9 @@ public:
push_process_state (int add_flag)
{
flag = add_flag;
-myself->process_state |= flag;
+InterlockedOr ((LONG *) &myself->process_state, flag);
}
- void pop () { myself->process_state &= ~(flag); }
+ void pop () { InterlockedAnd ((LONG *) &myself->process_state, ~(flag)); }
~push_process_state () { pop (); }
};
diff --git a/winsup/cygwin/pinfo.cc b/winsup/cygwin/pinfo.cc
index 1f26a3ccd..c69213f9a 100644
--- a/winsup/cygwin/pinfo.cc
+++ b/winsup/cygwin/pinfo.cc
@@ -69,7 +69,7 @@ pinfo::thisproc (HANDLE h)
child_info_spawn::handle_spawn. */
init (cygheap->pid, flags, h);
- procinfo->process_state |= PID_IN_USE;
+ InterlockedOr ((LONG *) &procinfo->process_state, PID_IN_USE);
procinfo->dwProcessId = myself_initial.dwProcessId;
procinfo->sendsig = myself_initial.sendsig;
wcscpy (procinfo->progname, myself_initial.progname);
@@ -89,7 +89,7 @@ pinfo_init (char **envp, int envc)
{
environ_init (envp, envc);
/* spawn has already set up a pid structure for us so we'll use that */
- myself->process_state |= PID_CYGPARENT;
+ InterlockedOr ((LONG *) &myself->process_state, PID_CYGPARENT);
}
else
{
@@ -108,10 +108,11 @@ pinfo_init (char **envp, int envc)
debug_printf ("Set nice to %d", myself->nice);
}
- myself->process_state |= PID_ACTIVE;
- myself->process_state &= ~(PID_INITIALIZING | PID_EXITED | PID_REAPED);
+ InterlockedOr ((LONG *) &myself->process_state, PID_ACTIVE);
+ InterlockedAnd ((LONG *) &myself->process_state,
+ ~(PID_INITIALIZING | PID_EXITED | PID_REAPED));
if (being_debugged ())
-myself->process_state |= PID_DEBUGGED;
+InterlockedOr ((LONG *) &myself->process_state, PID_DEBUGGED);
myself.preserve ();
debug_printf ("pid %d, pgid %d, process_state %y",
myself->pid, myself->pgid, myself->process_state);
diff --git a/winsup/cygwin/signal.cc b/winsup/cygwin/signal.cc
index 0bd64963f..f8ba67e75 100644
--- a/winsup/cygwin/signal.cc
+++ b/winsup/cygwin/signal.cc
@@ -456,9 +456,11 @@ sigaction_worker (int sig, const struct sigaction *newact,
sig_clear (sig, true);
if (sig == SIGCHL
[PATCH v2 0/3] Three fixes for signal handling
Takashi Yano (3): Cygwin: signal: Fix deadlock on SIGCONT Cygwin: signal: Fix a race issue on modifying _pinfo::process_state Cygwin: signal: Fix a problem that process hangs on exit [<= revised] winsup/cygwin/exceptions.cc | 29 winsup/cygwin/fork.cc| 5 +++-- winsup/cygwin/local_includes/pinfo.h | 4 ++-- winsup/cygwin/pinfo.cc | 11 ++- winsup/cygwin/signal.cc | 6 -- winsup/cygwin/sigproc.cc | 8 ++-- winsup/cygwin/spawn.cc | 6 +++--- 7 files changed, 41 insertions(+), 28 deletions(-) -- 2.45.1
[PATCH v2 1/3] Cygwin: signal: Fix deadlock on SIGCONT
If SIGCONT starts processing while __SIGFLUSHFAST is ongoing,
_main_tls->current_sig will never be cleared because the signal
processing is stopped while waiting for the wake-up event in the
main thread. This leads to a deadlock in the while loop waiting for
current_sig to be cleared. With this patch, the function returns to
wait_sig() if current_sig is set, rather than waiting for it in the
while loop.
Addresses: https://cygwin.com/pipermail/cygwin/2025-February/257473.html
Fixes: 9d2155089e87 ("(sigpacket::process): Call handle_SIGCONT early to deal
with SIGCONT.")
Reported-by: Christian Franke
Reviewed-by:
Signed-off-by: Takashi Yano
---
winsup/cygwin/exceptions.cc | 25 +++--
1 file changed, 15 insertions(+), 10 deletions(-)
diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index f576c5ff2..c6e82b6c5 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -1425,23 +1425,18 @@ _cygtls::handle_SIGCONT ()
if (NOTSTATE (myself, PID_STOPPED))
return;
- myself->stopsig = 0;
- myself->process_state &= ~PID_STOPPED;
- /* Carefully tell sig_handle_tty_stop to wake up.
- Make sure that any pending signal is handled before trying to
- send a new one. Then make sure that SIGCONT has been recognized
- before exiting the loop. */
- while (current_sig) /* Assume that it's ok to just test sig outside of a */
-yield (); /* lock since setup_handler does it this way. */
-
lock ();
current_sig = SIGCONT;
set_signal_arrived (); /* alert sig_handle_tty_stop */
unlock ();
+ /* Make sure that SIGCONT has been recognized before exiting the loop. */
while (current_sig == SIGCONT)
yield ();
+ myself->stopsig = 0;
+ myself->process_state &= ~PID_STOPPED;
+
/* Clear pending stop signals */
sig_clear (SIGSTOP, false);
sig_clear (SIGTSTP, false);
@@ -1473,7 +1468,17 @@ sigpacket::process ()
myself->rusage_self.ru_nsignals++;
if (si.si_signo == SIGCONT)
-_main_tls->handle_SIGCONT ();
+{
+ /* Carefully tell sig_handle_tty_stop to wake up.
+Make sure that any pending signal is handled before trying to
+send a new one. */
+ if (_main_tls->current_sig)
+ {
+ rc = -1;
+ goto done;
+ }
+ _main_tls->handle_SIGCONT ();
+}
/* SIGKILL is special. It always goes through. */
if (si.si_signo == SIGKILL)
--
2.45.1
[PATCH v2 3/3] Cygwin: signal: Fix a problem that process hangs on exit
The process that receives many SIGSTOP/SIGCONT signals sometimes hangs
on exit in sig_dispatch_pending(). This patch skips processing signals
in wait_sig() when exit_state > ES_EXIT_STARTING to avoid that situation.
Addresses: https://cygwin.com/pipermail/cygwin/2025-February/257473.html
Fixes: d243e51ef1d3 ("Cygwin: signal: Fix deadlock between main thread and sig
thread")
Reported-by: Christian Franke
Reviewed-by:
Signed-off-by: Takashi Yano
---
winsup/cygwin/sigproc.cc | 6 +-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc
index 8739f18f5..b519866d2 100644
--- a/winsup/cygwin/sigproc.cc
+++ b/winsup/cygwin/sigproc.cc
@@ -1374,7 +1374,11 @@ wait_sig (VOID *)
sigq.retry = false;
/* Don't process signals when we start exiting */
- if (exit_state > ES_EXIT_STARTING && pack.si.si_signo > 0)
+ if (exit_state > ES_EXIT_STARTING
+ && (pack.si.si_signo > 0
+ || pack.si.si_signo == __SIGNOHOLD
+ || pack.si.si_signo == __SIGFLUSH
+ || pack.si.si_signo == __SIGFLUSHFAST))
goto skip_process_signal;
sigset_t dummy_mask;
--
2.45.1
[PATCH 0/3] A few fixes for signal handling
Takashi Yano (3): Cygwin: signal: Fix deadlock on SIGCONT Cygwin: signal: Fix a race issue on modifying _pinfo::process_state Cygwin: signal: Fix a problem that process hangs on exit winsup/cygwin/exceptions.cc | 29 winsup/cygwin/fork.cc| 5 +++-- winsup/cygwin/local_includes/pinfo.h | 4 ++-- winsup/cygwin/pinfo.cc | 11 ++- winsup/cygwin/signal.cc | 6 -- winsup/cygwin/sigproc.cc | 5 +++-- winsup/cygwin/spawn.cc | 6 +++--- 7 files changed, 38 insertions(+), 28 deletions(-) -- 2.45.1
[PATCH 1/3] Cygwin: signal: Fix deadlock on SIGCONT
If SIGCONT starts processing while __SIGFLUSHFAST is ongoing,
_main_tls->current_sig will never be cleared because the signal
processing is stopped while waiting for the wake-up event in the
main thread. This leads to a deadlock in the while loop waiting for
current_sig to be cleared. With this patch, the function returns to
wait_sig() if current_sig is set, rather than waiting for it in the
while loop.
Addresses: https://cygwin.com/pipermail/cygwin/2025-February/257473.html
Fixes: 9d2155089e87 ("(sigpacket::process): Call handle_SIGCONT early to deal
with SIGCONT.")
Reported-by: Christian Franke
Signed-off-by: Takashi Yano
---
winsup/cygwin/exceptions.cc | 25 +++--
1 file changed, 15 insertions(+), 10 deletions(-)
diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index f576c5ff2..c6e82b6c5 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -1425,23 +1425,18 @@ _cygtls::handle_SIGCONT ()
if (NOTSTATE (myself, PID_STOPPED))
return;
- myself->stopsig = 0;
- myself->process_state &= ~PID_STOPPED;
- /* Carefully tell sig_handle_tty_stop to wake up.
- Make sure that any pending signal is handled before trying to
- send a new one. Then make sure that SIGCONT has been recognized
- before exiting the loop. */
- while (current_sig) /* Assume that it's ok to just test sig outside of a */
-yield (); /* lock since setup_handler does it this way. */
-
lock ();
current_sig = SIGCONT;
set_signal_arrived (); /* alert sig_handle_tty_stop */
unlock ();
+ /* Make sure that SIGCONT has been recognized before exiting the loop. */
while (current_sig == SIGCONT)
yield ();
+ myself->stopsig = 0;
+ myself->process_state &= ~PID_STOPPED;
+
/* Clear pending stop signals */
sig_clear (SIGSTOP, false);
sig_clear (SIGTSTP, false);
@@ -1473,7 +1468,17 @@ sigpacket::process ()
myself->rusage_self.ru_nsignals++;
if (si.si_signo == SIGCONT)
-_main_tls->handle_SIGCONT ();
+{
+ /* Carefully tell sig_handle_tty_stop to wake up.
+Make sure that any pending signal is handled before trying to
+send a new one. */
+ if (_main_tls->current_sig)
+ {
+ rc = -1;
+ goto done;
+ }
+ _main_tls->handle_SIGCONT ();
+}
/* SIGKILL is special. It always goes through. */
if (si.si_signo == SIGKILL)
--
2.45.1
[PATCH 2/3] Cygwin: signal: Fix a race issue on modifying _pinfo::process_state
The PID_STOPPED flag in _ponfo::process_state is sometimes accidentally
cleared due to a race condition when modifying it with the "|=" or "&="
operators. This patch uses InterlockedOr/And() instead to avoid the
race condition.
Addresses: https://cygwin.com/pipermail/cygwin/2025-February/257473.html
Fixes: 1fd5e000ace55 ("import winsup-2000-02-17 snapshot")
Reported-by: Christian Franke
Signed-off-by: Takashi Yano
---
winsup/cygwin/exceptions.cc | 6 +++---
winsup/cygwin/fork.cc| 5 +++--
winsup/cygwin/local_includes/pinfo.h | 4 ++--
winsup/cygwin/pinfo.cc | 11 ++-
winsup/cygwin/signal.cc | 6 --
winsup/cygwin/sigproc.cc | 2 +-
winsup/cygwin/spawn.cc | 6 +++---
7 files changed, 22 insertions(+), 18 deletions(-)
diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index c6e82b6c5..45c71cbdf 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -882,7 +882,7 @@ sig_handle_tty_stop (int sig, siginfo_t *, void *)
/* Silently ignore attempts to suspend if there is no accommodating
cygwin parent to deal with this behavior. */
if (!myself->cygstarted)
-myself->process_state &= ~PID_STOPPED;
+InterlockedAnd ((LONG *) &myself->process_state, ~PID_STOPPED);
else
{
_my_tls.incyg = 1;
@@ -948,7 +948,7 @@ _cygtls::interrupt_setup (siginfo_t& si, void *handler,
struct sigaction& siga)
if (handler == sig_handle_tty_stop)
{
myself->stopsig = 0;
- myself->process_state |= PID_STOPPED;
+ InterlockedOr ((LONG *) &myself->process_state, PID_STOPPED);
}
infodata = si;
@@ -1435,7 +1435,7 @@ _cygtls::handle_SIGCONT ()
yield ();
myself->stopsig = 0;
- myself->process_state &= ~PID_STOPPED;
+ InterlockedAnd ((LONG *) &myself->process_state, ~PID_STOPPED);
/* Clear pending stop signals */
sig_clear (SIGSTOP, false);
diff --git a/winsup/cygwin/fork.cc b/winsup/cygwin/fork.cc
index 41a533705..783971b76 100644
--- a/winsup/cygwin/fork.cc
+++ b/winsup/cygwin/fork.cc
@@ -678,8 +678,9 @@ dofork (void **proc, bool *with_forkables)
if (ischild)
{
- myself->process_state |= PID_ACTIVE;
- myself->process_state &= ~(PID_INITIALIZING | PID_EXITED | PID_REAPED);
+ InterlockedOr ((LONG *) &myself->process_state, PID_ACTIVE);
+ InterlockedAnd ((LONG *) &myself->process_state,
+ ~(PID_INITIALIZING | PID_EXITED | PID_REAPED));
}
else if (res < 0)
{
diff --git a/winsup/cygwin/local_includes/pinfo.h
b/winsup/cygwin/local_includes/pinfo.h
index 4de0f80dd..3086f9941 100644
--- a/winsup/cygwin/local_includes/pinfo.h
+++ b/winsup/cygwin/local_includes/pinfo.h
@@ -271,9 +271,9 @@ public:
push_process_state (int add_flag)
{
flag = add_flag;
-myself->process_state |= flag;
+InterlockedOr ((LONG *) &myself->process_state, flag);
}
- void pop () { myself->process_state &= ~(flag); }
+ void pop () { InterlockedAnd ((LONG *) &myself->process_state, ~(flag)); }
~push_process_state () { pop (); }
};
diff --git a/winsup/cygwin/pinfo.cc b/winsup/cygwin/pinfo.cc
index 1f26a3ccd..c69213f9a 100644
--- a/winsup/cygwin/pinfo.cc
+++ b/winsup/cygwin/pinfo.cc
@@ -69,7 +69,7 @@ pinfo::thisproc (HANDLE h)
child_info_spawn::handle_spawn. */
init (cygheap->pid, flags, h);
- procinfo->process_state |= PID_IN_USE;
+ InterlockedOr ((LONG *) &procinfo->process_state, PID_IN_USE);
procinfo->dwProcessId = myself_initial.dwProcessId;
procinfo->sendsig = myself_initial.sendsig;
wcscpy (procinfo->progname, myself_initial.progname);
@@ -89,7 +89,7 @@ pinfo_init (char **envp, int envc)
{
environ_init (envp, envc);
/* spawn has already set up a pid structure for us so we'll use that */
- myself->process_state |= PID_CYGPARENT;
+ InterlockedOr ((LONG *) &myself->process_state, PID_CYGPARENT);
}
else
{
@@ -108,10 +108,11 @@ pinfo_init (char **envp, int envc)
debug_printf ("Set nice to %d", myself->nice);
}
- myself->process_state |= PID_ACTIVE;
- myself->process_state &= ~(PID_INITIALIZING | PID_EXITED | PID_REAPED);
+ InterlockedOr ((LONG *) &myself->process_state, PID_ACTIVE);
+ InterlockedAnd ((LONG *) &myself->process_state,
+ ~(PID_INITIALIZING | PID_EXITED | PID_REAPED));
if (being_debugged ())
-myself->process_state |= PID_DEBUGGED;
+InterlockedOr ((LONG *) &myself->process_state, PID_DEBUGGED);
myself.preserve ();
debug_printf ("pid %d, pgid %d, process_state %y",
myself->pid, myself->pgid, myself->process_state);
diff --git a/winsup/cygwin/signal.cc b/winsup/cygwin/signal.cc
index 0bd64963f..f8ba67e75 100644
--- a/winsup/cygwin/signal.cc
+++ b/winsup/cygwin/signal.cc
@@ -456,9 +456,11 @@ sigaction_worker (int sig, const struct sigaction *newact,
sig_clear (sig, true);
if (sig == SIGCHLD)
[PATCH 3/3] Cygwin: signal: Fix a problem that process hangs on exit
The process that receives many SIGSTOP/SIGCONT signals sometimes hangs
on exit in sig_dispatch_pending(). This patch avoids processing signals
in sig_dispatch_pending() as if __SIGFLASHFAST is used.
Addresses: https://cygwin.com/pipermail/cygwin/2025-February/257473.html
Fixes: d243e51ef1d3 ("Cygwin: signal: Fix deadlock between main thread and sig
thread")
Reported-by: Christian Franke
Signed-off-by: Takashi Yano
---
winsup/cygwin/sigproc.cc | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc
index 8739f18f5..7cfa37d8f 100644
--- a/winsup/cygwin/sigproc.cc
+++ b/winsup/cygwin/sigproc.cc
@@ -743,7 +743,8 @@ sig_send (_pinfo *p, siginfo_t& si, _cygtls *tls)
}
unsigned cw_mask;
- cw_mask = pack.si.si_signo == __SIGFLUSHFAST ? 0 : cw_sig_restart;
+ cw_mask =
+(pack.si.si_signo == __SIGFLUSHFAST || exit_state) ? 0 : cw_sig_restart;
DWORD nb;
BOOL res;
--
2.45.1
