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Cygwin: timerfd: rework implementation

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timerfd_tracker and timerfd_shared classes:

- Just because handles are shared, we don't have to store them in
  shared memory.  Move share handles into timerfd_tracker class.

- Drop shared instance counter since it's not required anymore.
  timerfd_shared only stores the actual timer data.

- Drop timerfd_shared::create, just set clock id.

- Drop timerfd_shared::dtor, it's not required anymore.

- Drop timerfd_tracker::close, just call dtor where required.

- Rename timerfd_tracker::increment_instances to timerfd_tracker::dup.
  It's the only reason it exists...

- timerfd_tracker::dtor now checks the non-shared pointers for NULL
  before attempting to close them.

- timerfd_tracker::dtor handles decrementing the local instance count
  by itself.

- Add a method timerfd_tracker::init_fixup_after_fork_exec to set
  non-shared pointers to NULL.  Together with the dtor patches it
  fixes a problem with close_on_exec timerfd descriptors.

- Fix a bug in handling the thread synchronization event.  It's
  actually nice to create it before using it...

- Drop using sec_none{_nih} in InitializeObjectAttributes.  It's
  an unnecessary roundabout route just to get a NULL pointer.

- Slightly rework timechange window handling.

- Add more comments to explain what happens.

fhandler_timerfd:

- Drop cnew macro, it just hides what happens.

- fhandler_timerfd::fixup_after_exec now calls
  timerfd_tracker::init_fixup_after_fork_exec first, so a subsequent
  call to timerfd_tracker::dtor only works on valid handles.

- fhandler_timerfd::close directly calls timerfd_tracker::dtor now.

- Drop dtor call in fhandler_timerfd destructor.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen
2019-02-25 20:58:12 +01:00
parent a4e2eb6ba3
commit 98afd02be3
4 changed files with 226 additions and 250 deletions
Download Patch File Download Diff File Expand all files Collapse all files

296
winsup/cygwin/timerfd.cc
View File

@ -28,10 +28,9 @@ timerfd_tracker::create_timechange_window ()
WNDCLASSW wclass = { 0 };
WCHAR cname[NAME_MAX];
__small_swprintf (cname, L"Cygwin.timerfd.%u", winpid);
__small_swprintf (cname, L"Cygwin.timerfd.%p", this);
wclass.lpfnWndProc = DefWindowProcW;
wclass.hInstance = GetModuleHandle (NULL);
wclass.hbrBackground = (HBRUSH) (COLOR_WINDOW + 1);
wclass.hInstance = user_data->hmodule;
wclass.lpszClassName = cname;
atom = RegisterClassW (&wclass);
if (!atom)
@ -39,9 +38,9 @@ timerfd_tracker::create_timechange_window ()
else
{
window = CreateWindowExW (0, cname, cname, WS_POPUP, 0, 0, 0, 0,
NULL, NULL, NULL, NULL);
NULL, NULL, user_data->hmodule, NULL);
if (!window)
debug_printf ("RegisterClass %E");
debug_printf ("CreateWindowEx %E");
}
}
@ -51,7 +50,7 @@ timerfd_tracker::delete_timechange_window ()
if (window)
DestroyWindow (window);
if (atom)
UnregisterClassW ((LPWSTR) (uintptr_t) atom, GetModuleHandle (NULL));
UnregisterClassW ((LPWSTR) (uintptr_t) atom, user_data->hmodule);
}
void
@ -59,12 +58,13 @@ timerfd_tracker::handle_timechange_window ()
{
MSG msg;
if (PeekMessageW(&msg, NULL, 0, 0, PM_REMOVE) && msg.message != WM_QUIT)
while (PeekMessageW (&msg, NULL, 0, 0, PM_REMOVE | PM_QS_POSTMESSAGE)
&& msg.message != WM_QUIT)
{
DispatchMessageW(&msg);
DispatchMessageW (&msg);
if (msg.message == WM_TIMECHANGE
&& get_clockid () == CLOCK_REALTIME
&& (flags () & TFD_CANCEL_FLAGS) == TFD_CANCEL_FLAGS
&& (get_flags () & TFD_CANCEL_FLAGS) == TFD_CANCEL_FLAGS
&& enter_critical_section ())
{
/* make sure to handle each WM_TIMECHANGE only once! */
@ -84,7 +84,7 @@ DWORD
timerfd_tracker::thread_func ()
{
/* Outer loop: Is the timer armed? If not, wait for it. */
HANDLE armed[2] = { tfd_shared->arm_evt (),
HANDLE armed[2] = { arm_evt (),
cancel_evt };
create_timechange_window ();
@ -105,8 +105,8 @@ timerfd_tracker::thread_func ()
}
/* Inner loop: Timer expired? If not, wait for it. */
HANDLE expired[3] = { tfd_shared->timer (),
tfd_shared->disarm_evt (),
HANDLE expired[3] = { timer (),
disarm_evt (),
cancel_evt };
while (1)
@ -133,7 +133,7 @@ timerfd_tracker::thread_func ()
/* Make sure we haven't been abandoned and/or disarmed
in the meantime */
if (expiration_count () == -1LL
|| IsEventSignalled (tfd_shared->disarm_evt ()))
|| IsEventSignalled (disarm_evt ()))
{
leave_critical_section ();
goto disarmed;
@ -176,8 +176,7 @@ timerfd_tracker::thread_func ()
|| get_clockid () == CLOCK_BOOTTIME_ALARM);
LARGE_INTEGER DueTime = { QuadPart: -get_interval () };
NtSetTimer (tfd_shared->timer (), &DueTime, NULL, NULL,
Resume, 0, NULL);
NtSetTimer (timer (), &DueTime, NULL, NULL, Resume, 0, NULL);
}
}
/* Arm the expiry object */
@ -190,7 +189,8 @@ disarmed:
canceled:
delete_timechange_window ();
_my_tls._ctinfo->auto_release (); /* automatically return the cygthread to the cygthread pool */
/* automatically return the cygthread to the cygthread pool */
_my_tls._ctinfo->auto_release ();
return 0;
}
@ -202,21 +202,41 @@ timerfd_thread (VOID *arg)
}
int
timerfd_shared::create (clockid_t clock_id)
timerfd_tracker::create (clockid_t clock_id)
{
int ret;
NTSTATUS status;
OBJECT_ATTRIBUTES attr;
/* Create access mutex */
InitializeObjectAttributes (&attr, NULL, OBJ_INHERIT, NULL,
sec_none.lpSecurityDescriptor);
status = NtCreateMutant (&_access_mtx, MUTEX_ALL_ACCESS, &attr, FALSE);
const ACCESS_MASK access = STANDARD_RIGHTS_REQUIRED
| SECTION_MAP_READ | SECTION_MAP_WRITE;
SIZE_T vsize = PAGE_SIZE;
LARGE_INTEGER sectionsize = { QuadPart: PAGE_SIZE };
/* Valid clock? */
if (!get_clock (clock_id))
{
ret = -EINVAL;
goto err;
}
/* Create shared objects */
InitializeObjectAttributes (&attr, NULL, OBJ_INHERIT, NULL, NULL);
/* Create shared section */
status = NtCreateSection (&tfd_shared_hdl, access, &attr, &sectionsize,
PAGE_READWRITE, SEC_COMMIT, NULL);
if (!NT_SUCCESS (status))
{
ret = -geterrno_from_nt_status (status);
goto err;
}
/* Create access mutex */
status = NtCreateMutant (&_access_mtx, MUTEX_ALL_ACCESS, &attr, FALSE);
if (!NT_SUCCESS (status))
{
ret = -geterrno_from_nt_status (status);
goto err_close_tfd_shared_hdl;
}
/* Create "timer is armed" event, set to "Unsignaled" at creation time */
status = NtCreateEvent (&_arm_evt, EVENT_ALL_ACCESS, &attr,
NotificationEvent, FALSE);
@ -249,10 +269,48 @@ timerfd_shared::create (clockid_t clock_id)
ret = -geterrno_from_nt_status (status);
goto err_close_timer;
}
instance_count = 1;
_clockid = clock_id;
/* Create process-local cancel event for this processes timer thread
(has to be recreated after fork/exec)*/
InitializeObjectAttributes (&attr, NULL, 0, NULL, NULL);
status = NtCreateEvent (&cancel_evt, EVENT_ALL_ACCESS, &attr,
NotificationEvent, FALSE);
if (!NT_SUCCESS (status))
{
ret = -geterrno_from_nt_status (status);
goto err_close_expired_evt;
}
/* Create sync event for this processes timer thread */
status = NtCreateEvent (&sync_thr, EVENT_ALL_ACCESS, &attr,
NotificationEvent, FALSE);
if (!NT_SUCCESS (status))
{
ret = -geterrno_from_nt_status (status);
goto err_close_cancel_evt;
}
/* Create section mapping (has to be recreated after fork/exec) */
tfd_shared = NULL;
status = NtMapViewOfSection (tfd_shared_hdl, NtCurrentProcess (),
(void **) &tfd_shared, 0, PAGE_SIZE, NULL,
&vsize, ViewShare, 0, PAGE_READWRITE);
if (!NT_SUCCESS (status))
{
ret = -geterrno_from_nt_status (status);
goto err_close_sync_thr;
}
/* Initialize clock id */
set_clockid (clock_id);
/* Set our winpid for fixup_after_fork_exec */
winpid = GetCurrentProcessId ();
/* Start timerfd thread */
new cygthread (timerfd_thread, this, "timerfd", sync_thr);
return 0;
err_close_sync_thr:
NtClose (sync_thr);
err_close_cancel_evt:
NtClose (cancel_evt);
err_close_expired_evt:
NtClose (_expired_evt);
err_close_timer:
NtClose (_timer);
err_close_disarm_evt:
@ -261,118 +319,43 @@ err_close_arm_evt:
NtClose (_arm_evt);
err_close_access_mtx:
NtClose (_access_mtx);
err:
return ret;
}
int
timerfd_tracker::create (clockid_t clock_id)
{
int ret;
NTSTATUS status;
OBJECT_ATTRIBUTES attr;
const ACCESS_MASK access = STANDARD_RIGHTS_REQUIRED
| SECTION_MAP_READ | SECTION_MAP_WRITE;
SIZE_T vsize = PAGE_SIZE;
LARGE_INTEGER sectionsize = { QuadPart: PAGE_SIZE };
/* Valid clock? */
if (!get_clock (clock_id))
{
ret = -EINVAL;
goto err;
}
/* Create shared section. */
InitializeObjectAttributes (&attr, NULL, OBJ_INHERIT, NULL,
sec_none.lpSecurityDescriptor);
status = NtCreateSection (&tfd_shared_hdl, access, &attr,
&sectionsize, PAGE_READWRITE,
SEC_COMMIT, NULL);
if (!NT_SUCCESS (status))
{
ret = -geterrno_from_nt_status (status);
goto err;
}
/* Create section mapping (has to be repeated after fork/exec */
status = NtMapViewOfSection (tfd_shared_hdl, NtCurrentProcess (),
(void **) &tfd_shared, 0, PAGE_SIZE, NULL,
&vsize, ViewShare, MEM_TOP_DOWN, PAGE_READWRITE);
if (!NT_SUCCESS (status))
{
ret = -geterrno_from_nt_status (status);
goto err_close_tfd_shared_hdl;
}
/* Create cancel even for this processes timer thread */
InitializeObjectAttributes (&attr, NULL, 0, NULL,
sec_none_nih.lpSecurityDescriptor);
status = NtCreateEvent (&cancel_evt, EVENT_ALL_ACCESS, &attr,
NotificationEvent, FALSE);
if (!NT_SUCCESS (status))
{
ret = -geterrno_from_nt_status (status);
goto err_unmap_tfd_shared;
}
ret = tfd_shared->create (clock_id);
if (ret < 0)
goto err_close_cancel_evt;
winpid = GetCurrentProcessId ();
new cygthread (timerfd_thread, this, "timerfd", sync_thr);
return 0;
err_close_cancel_evt:
NtClose (cancel_evt);
err_unmap_tfd_shared:
NtUnmapViewOfSection (NtCurrentProcess (), tfd_shared);
err_close_tfd_shared_hdl:
NtClose (tfd_shared_hdl);
err:
return ret;
}
/* Return true if this was the last instance of a timerfd, session-wide,
false otherwise */
bool
timerfd_shared::dtor ()
{
if (instance_count > 0)
{
return false;
}
disarm_timer ();
NtClose (_timer);
NtClose (_arm_evt);
NtClose (_disarm_evt);
NtClose (_expired_evt);
NtClose (_access_mtx);
return true;
}
/* Return true if this was the last instance of a timerfd, session-wide,
/* Return true if this was the last instance of a timerfd, process-wide,
false otherwise. Basically this is a destructor, but one which may
notify the caller NOT to deleted the object. */
bool
timerfd_tracker::dtor ()
{
if (enter_critical_section ())
if (!enter_critical_section ())
return false;
if (decrement_instances () > 0)
{
if (local_instance_count > 0)
{
leave_critical_section ();
return false;
}
SetEvent (cancel_evt);
WaitForSingleObject (sync_thr, INFINITE);
if (tfd_shared->dtor ())
{
NtUnmapViewOfSection (NtCurrentProcess (), tfd_shared);
NtClose (tfd_shared_hdl);
}
else
leave_critical_section ();
leave_critical_section ();
return false;
}
NtClose (cancel_evt);
NtClose (sync_thr);
if (cancel_evt)
SetEvent (cancel_evt);
if (sync_thr)
{
WaitForSingleObject (sync_thr, INFINITE);
NtClose (sync_thr);
}
leave_critical_section ();
if (tfd_shared)
NtUnmapViewOfSection (NtCurrentProcess (), tfd_shared);
if (cancel_evt)
NtClose (cancel_evt);
NtClose (tfd_shared_hdl);
NtClose (_expired_evt);
NtClose (_timer);
NtClose (_disarm_evt);
NtClose (_arm_evt);
NtClose (_access_mtx);
return true;
}
@ -383,13 +366,6 @@ timerfd_tracker::dtor (timerfd_tracker *tfd)
cfree (tfd);
}
void
timerfd_tracker::close ()
{
InterlockedDecrement (&local_instance_count);
InterlockedDecrement (&tfd_shared->instance_count);
}
int
timerfd_tracker::ioctl_set_ticks (uint64_t new_exp_cnt)
{
@ -404,11 +380,22 @@ timerfd_tracker::ioctl_set_ticks (uint64_t new_exp_cnt)
return 0;
}
void
timerfd_tracker::init_fixup_after_fork_exec ()
{
/* Run this only if this is the first call, or all previous calls
came from close_on_exec descriptors */
if (winpid == GetCurrentProcessId ())
return;
tfd_shared = NULL;
cancel_evt = NULL;
sync_thr = NULL;
}
void
timerfd_tracker::fixup_after_fork_exec (bool execing)
{
NTSTATUS status;
PVOID base_address = NULL;
OBJECT_ATTRIBUTES attr;
SIZE_T vsize = PAGE_SIZE;
@ -416,24 +403,27 @@ timerfd_tracker::fixup_after_fork_exec (bool execing)
if (winpid == GetCurrentProcessId ())
return;
/* Recreate shared section mapping */
tfd_shared = NULL;
status = NtMapViewOfSection (tfd_shared_hdl, NtCurrentProcess (),
&base_address, 0, PAGE_SIZE, NULL,
(PVOID *) &tfd_shared, 0, PAGE_SIZE, NULL,
&vsize, ViewShare, 0, PAGE_READWRITE);
if (!NT_SUCCESS (status))
api_fatal ("Can't recreate shared timerfd section during %s, status %y!",
execing ? "execve" : "fork", status);
tfd_shared = (timerfd_shared *) base_address;
/* Increment global instance count by the number of instances in this
process */
InterlockedAdd (&tfd_shared->instance_count, local_instance_count);
/* Create cancel even for this processes timer thread */
InitializeObjectAttributes (&attr, NULL, 0, NULL,
sec_none_nih.lpSecurityDescriptor);
/* Create cancel event for this processes timer thread */
InitializeObjectAttributes (&attr, NULL, 0, NULL, NULL);
status = NtCreateEvent (&cancel_evt, EVENT_ALL_ACCESS, &attr,
NotificationEvent, FALSE);
if (!NT_SUCCESS (status))
api_fatal ("Can't recreate timerfd cancel event during %s, status %y!",
execing ? "execve" : "fork", status);
/* Create sync event for this processes timer thread */
InitializeObjectAttributes (&attr, NULL, 0, NULL, NULL);
status = NtCreateEvent (&sync_thr, EVENT_ALL_ACCESS, &attr,
NotificationEvent, FALSE);
if (!NT_SUCCESS (status))
api_fatal ("Can't recreate timerfd sync event during %s, status %y!",
execing ? "execve" : "fork", status);
/* Set winpid so we don't run this twice */
winpid = GetCurrentProcessId ();
new cygthread (timerfd_thread, this, "timerfd", sync_thr);
@ -509,7 +499,7 @@ timerfd_tracker::gettime (struct itimerspec *curr_value)
__try
{
if (IsEventSignalled (tfd_shared->disarm_evt ()))
if (IsEventSignalled (disarm_evt ()))
*curr_value = time_spec ();
else
{
@ -532,27 +522,28 @@ timerfd_tracker::gettime (struct itimerspec *curr_value)
}
int
timerfd_shared::arm_timer (int flags, const struct itimerspec *new_value)
timerfd_tracker::arm_timer (int flags, const struct itimerspec *new_value)
{
LONG64 interval;
LONG64 ts;
NTSTATUS status;
LARGE_INTEGER DueTime;
BOOLEAN Resume;
LONG Period;
ResetEvent (_disarm_evt);
ResetEvent (disarm_evt ());
/* Convert incoming itimerspec into 100ns interval and timestamp */
_interval = new_value->it_interval.tv_sec * NS100PERSEC
+ (new_value->it_interval.tv_nsec + (NSPERSEC / NS100PERSEC) - 1)
/ (NSPERSEC / NS100PERSEC);
interval = new_value->it_interval.tv_sec * NS100PERSEC
+ (new_value->it_interval.tv_nsec + (NSPERSEC / NS100PERSEC) - 1)
/ (NSPERSEC / NS100PERSEC);
ts = new_value->it_value.tv_sec * NS100PERSEC
+ (new_value->it_value.tv_nsec + (NSPERSEC / NS100PERSEC) - 1)
/ (NSPERSEC / NS100PERSEC);
_flags = flags;
set_flags (flags);
if (flags & TFD_TIMER_ABSTIME)
{
if (_clockid == CLOCK_REALTIME)
if (get_clockid () == CLOCK_REALTIME)
DueTime.QuadPart = ts + FACTOR;
else /* non-REALTIME clocks require relative DueTime. */
{
@ -570,17 +561,18 @@ timerfd_shared::arm_timer (int flags, const struct itimerspec *new_value)
DueTime.QuadPart = -ts;
ts += get_clock_now ();
}
set_exp_ts (ts);
time_spec () = *new_value;
set_exp_ts (ts);
set_interval (interval);
read_and_reset_expiration_count ();
/* Note: Advanced Power Settings -> Sleep -> Allow Wake Timers
since W10 1709 */
Resume = (_clockid == CLOCK_REALTIME_ALARM
|| _clockid == CLOCK_BOOTTIME_ALARM);
if (_interval > INT_MAX * (NS100PERSEC / MSPERSEC))
Resume = (get_clockid () == CLOCK_REALTIME_ALARM
|| get_clockid () == CLOCK_BOOTTIME_ALARM);
if (interval > INT_MAX * (NS100PERSEC / MSPERSEC))
Period = 0;
else
Period = (_interval + (NS100PERSEC / MSPERSEC) - 1)
Period = (interval + (NS100PERSEC / MSPERSEC) - 1)
/ (NS100PERSEC / MSPERSEC);
status = NtSetTimer (timer (), &DueTime, NULL, NULL, Resume, Period, NULL);
if (!NT_SUCCESS (status))
@ -589,7 +581,7 @@ timerfd_shared::arm_timer (int flags, const struct itimerspec *new_value)
return -geterrno_from_nt_status (status);
}
SetEvent (_arm_evt);
SetEvent (arm_evt ());
return 0;
}