[patch 03/22] pollfs: asynchronously wait for a signal

[Davi Arnaut]

Add a wait queue to the task_struct in order to be able to
associate (wait for) a signal with other resources.

Signed-off-by: Davi E. M. Arnaut <[EMAIL PROTECTED]>

---
 include/linux/init_task.h |    1 +
 include/linux/sched.h     |    1 +
 kernel/fork.c             |    1 +
 kernel/signal.c           |    5 +++++
 4 files changed, 8 insertions(+)

Index: linux-2.6/include/linux/sched.h
===================================================================
--- linux-2.6.orig/include/linux/sched.h
+++ linux-2.6/include/linux/sched.h
@@ -939,6 +939,7 @@ struct task_struct {
        sigset_t blocked, real_blocked;
        sigset_t saved_sigmask;         /* To be restored with 
TIF_RESTORE_SIGMASK */
        struct sigpending pending;
+       wait_queue_head_t sigwait;
 
        unsigned long sas_ss_sp;
        size_t sas_ss_size;
Index: linux-2.6/include/linux/init_task.h
===================================================================
--- linux-2.6.orig/include/linux/init_task.h
+++ linux-2.6/include/linux/init_task.h
@@ -134,6 +134,7 @@ extern struct group_info init_groups;
                .list = LIST_HEAD_INIT(tsk.pending.list),               \
                .signal = {{0}}},                                       \
        .blocked        = {{0}},                                        \
+       .sigwait        = __WAIT_QUEUE_HEAD_INITIALIZER(tsk.sigwait),   \
        .alloc_lock     = __SPIN_LOCK_UNLOCKED(tsk.alloc_lock),         \
        .journal_info   = NULL,                                         \
        .cpu_timers     = INIT_CPU_TIMERS(tsk.cpu_timers),              \
Index: linux-2.6/kernel/fork.c
===================================================================
--- linux-2.6.orig/kernel/fork.c
+++ linux-2.6/kernel/fork.c
@@ -1034,6 +1034,7 @@ static struct task_struct *copy_process(
 
        clear_tsk_thread_flag(p, TIF_SIGPENDING);
        init_sigpending(&p->pending);
+       init_waitqueue_head(&p->sigwait);
 
        p->utime = cputime_zero;
        p->stime = cputime_zero;
Index: linux-2.6/kernel/signal.c
===================================================================
--- linux-2.6.orig/kernel/signal.c
+++ linux-2.6/kernel/signal.c
@@ -224,6 +224,8 @@ fastcall void recalc_sigpending_tsk(stru
                set_tsk_thread_flag(t, TIF_SIGPENDING);
        else
                clear_tsk_thread_flag(t, TIF_SIGPENDING);
+
+       wake_up_interruptible_sync(&t->sigwait);
 }
 
 void recalc_sigpending(void)
@@ -759,6 +761,7 @@ static int send_signal(int sig, struct s
                                              info->si_code >= 0)));
        if (q) {
                list_add_tail(&q->list, &signals->list);
+               wake_up_interruptible_sync(&t->sigwait);
                switch ((unsigned long) info) {
                case (unsigned long) SEND_SIG_NOINFO:
                        q->info.si_signo = sig;
@@ -1404,6 +1407,7 @@ int send_sigqueue(int sig, struct sigque
 
        list_add_tail(&q->list, &p->pending.list);
        sigaddset(&p->pending.signal, sig);
+       wake_up_interruptible_sync(&p->sigwait);
        if (!sigismember(&p->blocked, sig))
                signal_wake_up(p, sig == SIGKILL);
 
@@ -1453,6 +1457,7 @@ send_group_sigqueue(int sig, struct sigq
        list_add_tail(&q->list, &p->signal->shared_pending.list);
        sigaddset(&p->signal->shared_pending.signal, sig);
 
+       wake_up_interruptible_sync(&p->sigwait);
        __group_complete_signal(sig, p);
 out:
        spin_unlock_irqrestore(&p->sighand->siglock, flags);

--
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