[PATCH v2 2/6] signal: introduce do_sigtimedwait() to factor outcompat/native code

From: Oleg Nesterov
Date: Tue Apr 26 2011 - 15:50:36 EST

Factor out the common code in sys_rt_sigtimedwait/compat_sys_rt_sigtimedwait
to the new helper, do_sigtimedwait().

Add the comment to document the extra tick we add to timespec_to_jiffies(ts),
thanks to Linus who explained this to me.

Perhaps it would be better to move compat_sys_rt_sigtimedwait() into
signal.c under CONFIG_COMPAT, then we can make do_sigtimedwait() static.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---

include/linux/signal.h | 2
kernel/signal.c | 104 +++++++++++++++++++++++++++----------------------
kernel/compat.c | 39 ++----------------
3 files changed, 67 insertions(+), 78 deletions(-)

--- sigprocmask/include/linux/signal.h~2_do_sigtimedwait 2011-04-26 19:52:30.000000000 +0200
+++ sigprocmask/include/linux/signal.h 2011-04-26 19:53:42.000000000 +0200
@@ -242,6 +242,8 @@ extern int __group_send_sig_info(int, st
extern long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig,
siginfo_t *info);
extern long do_sigpending(void __user *, unsigned long);
+extern int do_sigtimedwait(const sigset_t *, siginfo_t *,
+ const struct timespec *);
extern int sigprocmask(int, sigset_t *, sigset_t *);
extern void set_current_blocked(const sigset_t *);
extern int show_unhandled_signals;
--- sigprocmask/kernel/signal.c~2_do_sigtimedwait 2011-04-26 19:53:19.000000000 +0200
+++ sigprocmask/kernel/signal.c 2011-04-26 19:53:42.000000000 +0200
@@ -2311,6 +2311,60 @@ int copy_siginfo_to_user(siginfo_t __use

#endif

+int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
+ const struct timespec *ts)
+{
+ struct task_struct *tsk = current;
+ long timeout = MAX_SCHEDULE_TIMEOUT;
+ sigset_t mask = *which;
+ int sig;
+
+ if (ts) {
+ if (!timespec_valid(ts))
+ return -EINVAL;
+ timeout = timespec_to_jiffies(ts);
+ /*
+ * We can be close to the next tick, add another one
+ * to ensure we will wait at least the time asked for.
+ */
+ if (ts->tv_sec || ts->tv_nsec)
+ timeout++;
+ }
+
+ /*
+ * Invert the set of allowed signals to get those we want to block.
+ */
+ sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
+ signotset(&mask);
+
+ spin_lock_irq(&tsk->sighand->siglock);
+ sig = dequeue_signal(tsk, &mask, info);
+ if (!sig && timeout) {
+ /*
+ * None ready, temporarily unblock those we're interested
+ * while we are sleeping in so that we'll be awakened when
+ * they arrive.
+ */
+ tsk->real_blocked = tsk->blocked;
+ sigandsets(&tsk->blocked, &tsk->blocked, &mask);
+ recalc_sigpending();
+ spin_unlock_irq(&tsk->sighand->siglock);
+
+ timeout = schedule_timeout_interruptible(timeout);
+
+ spin_lock_irq(&tsk->sighand->siglock);
+ sig = dequeue_signal(tsk, &mask, info);
+ tsk->blocked = tsk->real_blocked;
+ siginitset(&tsk->real_blocked, 0);
+ recalc_sigpending();
+ }
+ spin_unlock_irq(&tsk->sighand->siglock);
+
+ if (sig)
+ return sig;
+ return timeout ? -EINTR : -EAGAIN;
+}
+
/**
* sys_rt_sigtimedwait - synchronously wait for queued signals specified
* in @uthese
@@ -2323,11 +2377,10 @@ SYSCALL_DEFINE4(rt_sigtimedwait, const s
siginfo_t __user *, uinfo, const struct timespec __user *, uts,
size_t, sigsetsize)
{
- int ret, sig;
sigset_t these;
struct timespec ts;
siginfo_t info;
- long timeout;
+ int ret;

/* XXX: Don't preclude handling different sized sigset_t's. */
if (sigsetsize != sizeof(sigset_t))
@@ -2336,55 +2389,16 @@ SYSCALL_DEFINE4(rt_sigtimedwait, const s
if (copy_from_user(&these, uthese, sizeof(these)))
return -EFAULT;

- /*
- * Invert the set of allowed signals to get those we
- * want to block.
- */
- sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
- signotset(&these);
-
- timeout = MAX_SCHEDULE_TIMEOUT;
if (uts) {
if (copy_from_user(&ts, uts, sizeof(ts)))
return -EFAULT;
- if (!timespec_valid(&ts))
- return -EINVAL;
- timeout = timespec_to_jiffies(&ts) + (ts.tv_sec || ts.tv_nsec);
}

- spin_lock_irq(&current->sighand->siglock);
- sig = dequeue_signal(current, &these, &info);
- if (!sig && timeout) {
- /*
- * None ready -- temporarily unblock those we're
- * interested while we are sleeping in so that we'll
- * be awakened when they arrive.
- */
- current->real_blocked = current->blocked;
- sigandsets(&current->blocked, &current->blocked, &these);
- recalc_sigpending();
- spin_unlock_irq(&current->sighand->siglock);
-
- timeout = schedule_timeout_interruptible(timeout);
-
- spin_lock_irq(&current->sighand->siglock);
- sig = dequeue_signal(current, &these, &info);
- current->blocked = current->real_blocked;
- siginitset(&current->real_blocked, 0);
- recalc_sigpending();
- }
- spin_unlock_irq(&current->sighand->siglock);
+ ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);

- if (sig) {
- ret = sig;
- if (uinfo) {
- if (copy_siginfo_to_user(uinfo, &info))
- ret = -EFAULT;
- }
- } else {
- ret = -EAGAIN;
- if (timeout)
- ret = -EINTR;
+ if (ret > 0 && uinfo) {
+ if (copy_siginfo_to_user(uinfo, &info))
+ ret = -EFAULT;
}

return ret;
--- sigprocmask/kernel/compat.c~2_do_sigtimedwait 2011-04-26 19:53:19.000000000 +0200
+++ sigprocmask/kernel/compat.c 2011-04-26 19:53:42.000000000 +0200
@@ -890,10 +890,9 @@ compat_sys_rt_sigtimedwait (compat_sigse
{
compat_sigset_t s32;
sigset_t s;
- int sig;
struct timespec t;
siginfo_t info;
- long ret, timeout;
+ long ret;

if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
@@ -901,45 +900,19 @@ compat_sys_rt_sigtimedwait (compat_sigse
if (copy_from_user(&s32, uthese, sizeof(compat_sigset_t)))
return -EFAULT;
sigset_from_compat(&s, &s32);
- sigdelsetmask(&s,sigmask(SIGKILL)|sigmask(SIGSTOP));
- signotset(&s);

- timeout = MAX_SCHEDULE_TIMEOUT;
if (uts) {
- if (get_compat_timespec (&t, uts))
+ if (get_compat_timespec(&t, uts))
return -EFAULT;
- if (!timespec_valid(&t))
- return -EINVAL;
- timeout = timespec_to_jiffies(&t) + (t.tv_sec || t.tv_nsec);
}

- spin_lock_irq(&current->sighand->siglock);
- sig = dequeue_signal(current, &s, &info);
- if (!sig && timeout) {
- current->real_blocked = current->blocked;
- sigandsets(&current->blocked, &current->blocked, &s);
- recalc_sigpending();
- spin_unlock_irq(&current->sighand->siglock);
-
- timeout = schedule_timeout_interruptible(timeout);
+ ret = do_sigtimedwait(&s, &info, uts ? &t : NULL);

- spin_lock_irq(&current->sighand->siglock);
- sig = dequeue_signal(current, &s, &info);
- current->blocked = current->real_blocked;
- siginitset(&current->real_blocked, 0);
- recalc_sigpending();
+ if (ret > 0 && uinfo) {
+ if (copy_siginfo_to_user32(uinfo, &info))
+ ret = -EFAULT;
}
- spin_unlock_irq(&current->sighand->siglock);

- if (sig) {
- ret = sig;
- if (uinfo) {
- if (copy_siginfo_to_user32(uinfo, &info))
- ret = -EFAULT;
- }
- } else {
- ret = timeout?-EINTR:-EAGAIN;
- }
return ret;

}

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