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Simplify timerfd configuration and fix some minor glitches.

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* configure.ac (HAVE_TIMERFD): Define only if TFD_CLOEXEC works,
since the code leaked file descriptors to children when !TFD_CLOEXEC.
(HAVE_TIMERFD_CLOEXEC): Remove; no longer used.
* m4/clock_time.m4 (gl_CLOCK_TIME): Don't check for clock_getres.
This reverts the previous change to this file, so it matches
gnulib again.
* src/atimer.c (TIMERFD_CREATE_FLAGS): Remove; we now assume TFD_CLOEXEC.
(alarm_timer, alarm_timer_ok, set_alarm, init_atimer):
Fall back on timer_create if timerfd_create fails at runtime.
(resolution) [HAVE_CLOCK_GETRES]: Remove; we now rely on the
kernel primitives to do resolution.  All uses removed.
(timerfd) [!HAVE_TIMERFD]: Define to be -1, for convenience.
(turn_on_atimers): Clear timer_create-based timers too,
for consistency.
This commit is contained in:
Paul Eggert 2014-07-31 13:17:01 -07:00
parent f3655f35cc
commit 5c6476b48a
5 changed files with 87 additions and 92 deletions
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10
ChangeLog
View file

@ -1,3 +1,13 @@
2014-07-31 Paul Eggert <eggert@cs.ucla.edu>
Simplify timerfd configuration and fix some minor glitches.
* configure.ac (HAVE_TIMERFD): Define only if TFD_CLOEXEC works,
since the code leaked file descriptors to children when !TFD_CLOEXEC.
(HAVE_TIMERFD_CLOEXEC): Remove; no longer used.
* m4/clock_time.m4 (gl_CLOCK_TIME): Don't check for clock_getres.
This reverts the previous change to this file, so it matches
gnulib again.
2014-07-28 Dmitry Antipov <dmantipov@yandex.ru>
* configure.ac (toplevel): Check whether GNU/Linux-specific

33
configure.ac
View file

@ -1539,7 +1539,7 @@ if test "$ac_cv_header_sys_sysinfo_h" = yes; then
AC_DEFINE(LINUX_SYSINFO_UNIT, 1,
[Define to 1 if Linux sysinfo sizes are in multiples of mem_unit bytes.]))
fi
fi
fi
dnl On Solaris 8 there's a compilation warning for term.h because
dnl it doesn't define `bool'.
@ -3711,25 +3711,18 @@ AC_SUBST(LIBS_TERMCAP)
AC_SUBST(TERMCAP_OBJ)
# GNU/Linux-specific timer functions.
if test $opsys = gnu-linux; then
AC_MSG_CHECKING([whether Linux timerfd functions are supported])
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/timerfd.h>]],
[[timerfd_create (CLOCK_REALTIME, 0);
timerfd_settime (0, 0, NULL, NULL)]])],
emacs_cv_linux_timerfd=yes, emacs_cv_linux_timerfd=no)
AC_MSG_RESULT([$emacs_cv_linux_timerfd])
if test $emacs_cv_linux_timerfd = yes; then
AC_DEFINE(HAVE_TIMERFD, 1, [Define to 1 if Linux timerfd functions are supported.])
AC_MSG_CHECKING([whether TFD_CLOEXEC is defined])
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/timerfd.h>]],
[[timerfd_create (CLOCK_REALTIME, TFD_CLOEXEC)]])],
emacs_cv_tfd_cloexec=yes, emacs_cv_tfd_cloexec=no)
AC_MSG_RESULT([$emacs_cv_tfd_cloexec])
if test $emacs_cv_tfd_cloexec = yes; then
AC_DEFINE(HAVE_TIMERFD_CLOEXEC, 1, [Define to 1 if TFD_CLOEXEC is defined.])
fi
fi
fi
AC_CACHE_CHECK([for timerfd interface], [emacs_cv_have_timerfd],
[AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM([[#include <sys/timerfd.h>
]],
[[timerfd_create (CLOCK_REALTIME, TFD_CLOEXEC);
timerfd_settime (0, TFD_TIMER_ABSTIME, 0, 0);]])],
[emacs_cv_have_timerfd=yes],
[emacs_cv_have_timerfd=no])])
if test "$emacs_cv_have_timerfd" = yes; then
AC_DEFINE([HAVE_TIMERFD], 1,
[Define to 1 if timerfd functions are supported as in GNU/Linux.])
fi
# Do we have res_init, for detecting changes in /etc/resolv.conf?
# On Darwin, res_init appears not to be useful: see bug#562 and

2
m4/clock_time.m4
View file

@ -26,6 +26,6 @@ AC_DEFUN([gl_CLOCK_TIME],
AC_SEARCH_LIBS([clock_gettime], [rt posix4],
[test "$ac_cv_search_clock_gettime" = "none required" ||
LIB_CLOCK_GETTIME=$ac_cv_search_clock_gettime])
AC_CHECK_FUNCS([clock_getres clock_gettime clock_settime])
AC_CHECK_FUNCS([clock_gettime clock_settime])
LIBS=$gl_saved_libs
])

10
src/ChangeLog
View file

@ -1,5 +1,15 @@
2014-07-31 Paul Eggert <eggert@cs.ucla.edu>
Simplify timerfd configuration and fix some minor glitches.
* atimer.c (TIMERFD_CREATE_FLAGS): Remove; we now assume TFD_CLOEXEC.
(alarm_timer, alarm_timer_ok, set_alarm, init_atimer):
Fall back on timer_create if timerfd_create fails at runtime.
(resolution) [HAVE_CLOCK_GETRES]: Remove; we now rely on the
kernel primitives to do resolution. All uses removed.
(timerfd) [!HAVE_TIMERFD]: Define to be -1, for convenience.
(turn_on_atimers): Clear timer_create-based timers too,
for consistency.
* frame.c (x_set_frame_parameters): Don't use uninitialized locals.
Without this change, the code can access the local variable 'width'
even when it has not been initialized, and likewise for 'height';

124
src/atimer.c
View file

@ -27,13 +27,8 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
#include <unistd.h>
#ifdef HAVE_TIMERFD
#include <sys/timerfd.h>
#ifdef HAVE_TIMERFD_CLOEXEC
#define TIMERFD_CREATE_FLAGS TFD_CLOEXEC
#else
#define TIMERFD_CREATE_FLAGS 0
#endif /* HAVE_TIMERFD_CLOEXEC */
#endif /* HAVE_TIMERFD */
# include <sys/timerfd.h>
#endif
/* Free-list of atimer structures. */
@ -49,23 +44,18 @@ static struct atimer *stopped_atimers;
static struct atimer *atimers;
#if defined (HAVE_TIMERFD)
/* File descriptor returned by timerfd_create. GNU/Linux-specific. */
static int timerfd;
#elif defined (HAVE_ITIMERSPEC)
/* The alarm timer used if POSIX timers are available. */
#ifdef HAVE_ITIMERSPEC
/* The alarm timer and whether it was properly initialized, if
POSIX timers are available. */
static timer_t alarm_timer;
#endif
static bool alarm_timer_ok;
#if defined (HAVE_TIMERFD) || defined (HAVE_ITIMERSPEC)
/* Non-zero if one of the above was successfully initialized. Do not
use bool due to special treatment if HAVE_TIMERFD, see below. */
static int special_timer_available;
#endif
#ifdef HAVE_CLOCK_GETRES
/* Resolution of CLOCK_REALTIME clock. */
static struct timespec resolution;
# ifdef HAVE_TIMERFD
/* File descriptor for timer, or -1 if it could not be created. */
static int timerfd;
# else
enum { timerfd = -1 };
# endif
#endif
/* Block/unblock SIGALRM. */
@ -92,20 +82,20 @@ static void schedule_atimer (struct atimer *);
static struct atimer *append_atimer_lists (struct atimer *,
struct atimer *);
/* Start a new atimer of type TYPE. TIME specifies when the timer is
/* Start a new atimer of type TYPE. TIMESTAMP specifies when the timer is
ripe. FN is the function to call when the timer fires.
CLIENT_DATA is stored in the client_data member of the atimer
structure returned and so made available to FN when it is called.
If TYPE is ATIMER_ABSOLUTE, TIME is the absolute time at which the
If TYPE is ATIMER_ABSOLUTE, TIMESTAMP is the absolute time at which the
timer fires.
If TYPE is ATIMER_RELATIVE, the timer is ripe TIME s/us in the
If TYPE is ATIMER_RELATIVE, the timer is ripe TIMESTAMP seconds in the
future.
In both cases, the timer is automatically freed after it has fired.
If TYPE is ATIMER_CONTINUOUS, the timer fires every TIME s/us.
If TYPE is ATIMER_CONTINUOUS, the timer fires every TIMESTAMP seconds.
Value is a pointer to the atimer started. It can be used in calls
to cancel_atimer; don't free it yourself. */
@ -117,16 +107,10 @@ start_atimer (enum atimer_type type, struct timespec timestamp,
struct atimer *t;
sigset_t oldset;
#if !defined (HAVE_SETITIMER)
/* Round TIME up to the next full second if we don't have itimers. */
/* Round TIMESTAMP up to the next full second if we don't have itimers. */
#ifndef HAVE_SETITIMER
if (timestamp.tv_nsec != 0 && timestamp.tv_sec < TYPE_MAXIMUM (time_t))
timestamp = make_timespec (timestamp.tv_sec + 1, 0);
#elif defined (HAVE_CLOCK_GETRES)
/* Check that the system clock is precise enough. If
not, round TIME up to the system clock resolution. */
if (timespec_valid_p (resolution)
&& timespec_cmp (timestamp, resolution) < 0)
timestamp = resolution;
#endif /* not HAVE_SETITIMER */
/* Get an atimer structure from the free-list, or allocate
@ -311,25 +295,24 @@ set_alarm (void)
#endif
struct timespec now, interval;
#if defined (HAVE_TIMERFD) || defined (HAVE_ITIMERSPEC)
if (special_timer_available)
#ifdef HAVE_ITIMERSPEC
if (0 <= timerfd || alarm_timer_ok)
{
struct itimerspec ispec;
ispec.it_value = atimers->expiration;
ispec.it_interval.tv_sec = ispec.it_interval.tv_nsec = 0;
#if defined (HAVE_TIMERFD)
if (special_timer_available == 1)
# ifdef HAVE_TIMERFD
if (timerfd_settime (timerfd, TFD_TIMER_ABSTIME, &ispec, 0) == 0)
{
add_timer_wait_descriptor (timerfd);
special_timer_available++;
return;
}
if (timerfd_settime (timerfd, TFD_TIMER_ABSTIME, &ispec, 0) == 0)
#elif defined (HAVE_ITIMERSPEC)
if (timer_settime (alarm_timer, TIMER_ABSTIME, &ispec, 0) == 0)
#endif
# endif
if (alarm_timer_ok
&& timer_settime (alarm_timer, TIMER_ABSTIME, &ispec, 0) == 0)
return;
}
#endif /* HAVE_TIMERFD || HAVE_ITIMERSPEC */
#endif
/* Determine interval till the next timer is ripe.
Don't set the interval to 0; this disables the timer. */
@ -453,15 +436,15 @@ turn_on_atimers (bool on)
set_alarm ();
else
{
#ifdef HAVE_TIMERFD
if (special_timer_available > 1)
{
struct itimerspec ispec;
memset (&ispec, 0, sizeof (ispec));
/* Writing zero expiration time should disarm it. */
timerfd_settime (timerfd, TFD_TIMER_ABSTIME, &ispec, 0);
}
#endif /* HAVE_TIMERFD */
#ifdef HAVE_ITIMERSPEC
struct itimerspec ispec;
memset (&ispec, 0, sizeof ispec);
if (alarm_timer_ok)
timer_settime (alarm_timer, TIMER_ABSTIME, &ispec, 0);
# ifdef HAVE_TIMERFD
timerfd_settime (timerfd, TFD_TIMER_ABSTIME, &ispec, 0);
# endif
#endif
alarm (0);
}
}
@ -494,14 +477,14 @@ debug_timer_callback (struct atimer *t)
r->intime = 0;
else if (result >= 0)
{
#ifdef HAVE_SETITIMER
#ifdef HAVE_SETITIMER
struct timespec delta = timespec_sub (now, r->expected);
/* Too late if later than expected + 0.01s. FIXME:
this should depend from system clock resolution. */
if (timespec_cmp (delta, make_timespec (0, 10000000)) > 0)
r->intime = 0;
else
#endif /* HAVE_SETITIMER */
#endif /* HAVE_SETITIMER */
r->intime = 1;
}
}
@ -543,21 +526,20 @@ Return t if all self-tests are passed, nil otherwise. */)
void
init_atimer (void)
{
#if defined (HAVE_TIMERFD)
timerfd = timerfd_create (CLOCK_REALTIME, TIMERFD_CREATE_FLAGS);
special_timer_available = !!(timerfd != -1);
#elif defined (HAVE_ITIMERSPEC)
struct sigevent sigev;
sigev.sigev_notify = SIGEV_SIGNAL;
sigev.sigev_signo = SIGALRM;
sigev.sigev_value.sival_ptr = &alarm_timer;
special_timer_available
= timer_create (CLOCK_REALTIME, &sigev, &alarm_timer) == 0;
#endif /* HAVE_TIMERFD */
#ifdef HAVE_CLOCK_GETRES
if (clock_getres (CLOCK_REALTIME, &resolution))
resolution = invalid_timespec ();
#endif
#ifdef HAVE_ITIMERSPEC
# ifdef HAVE_TIMERFD
timerfd = timerfd_create (CLOCK_REALTIME, TFD_CLOEXEC);
# endif
if (timerfd < 0)
{
struct sigevent sigev;
sigev.sigev_notify = SIGEV_SIGNAL;
sigev.sigev_signo = SIGALRM;
sigev.sigev_value.sival_ptr = &alarm_timer;
alarm_timer_ok
= timer_create (CLOCK_REALTIME, &sigev, &alarm_timer) == 0;
}
#endif
free_atimers = stopped_atimers = atimers = NULL;
/* pending_signals is initialized in init_keyboard. */
@ -567,5 +549,5 @@ init_atimer (void)
#ifdef ENABLE_CHECKING
defsubr (&Sdebug_timer_check);
#endif
#endif
}