#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/ptrace.h>
-#include <linux/posix-timers.h>
#include <linux/signal.h>
#include <linux/audit.h>
#include <linux/capability.h>
#define sig_kernel_stop(sig) \
(((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_STOP_MASK))
+#define sig_needs_tasklist(sig) ((sig) == SIGCONT)
+
#define sig_user_defined(t, signr) \
(((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))
kmem_cache_free(sigqueue_cachep, q);
}
-static void flush_sigqueue(struct sigpending *queue)
+void flush_sigqueue(struct sigpending *queue)
{
struct sigqueue *q;
/*
* Flush all pending signals for a task.
*/
-
-void
-flush_signals(struct task_struct *t)
+void flush_signals(struct task_struct *t)
{
unsigned long flags;
}
/*
- * This function expects the tasklist_lock write-locked.
- */
-void __exit_sighand(struct task_struct *tsk)
-{
- struct sighand_struct * sighand = tsk->sighand;
-
- /* Ok, we're done with the signal handlers */
- tsk->sighand = NULL;
- if (atomic_dec_and_test(&sighand->count))
- sighand_free(sighand);
-}
-
-void exit_sighand(struct task_struct *tsk)
-{
- write_lock_irq(&tasklist_lock);
- rcu_read_lock();
- if (tsk->sighand != NULL) {
- struct sighand_struct *sighand = rcu_dereference(tsk->sighand);
- spin_lock(&sighand->siglock);
- __exit_sighand(tsk);
- spin_unlock(&sighand->siglock);
- }
- rcu_read_unlock();
- write_unlock_irq(&tasklist_lock);
-}
-
-/*
- * This function expects the tasklist_lock write-locked.
- */
-void __exit_signal(struct task_struct *tsk)
-{
- struct signal_struct * sig = tsk->signal;
- struct sighand_struct * sighand;
-
- if (!sig)
- BUG();
- if (!atomic_read(&sig->count))
- BUG();
- rcu_read_lock();
- sighand = rcu_dereference(tsk->sighand);
- spin_lock(&sighand->siglock);
- posix_cpu_timers_exit(tsk);
- if (atomic_dec_and_test(&sig->count)) {
- posix_cpu_timers_exit_group(tsk);
- tsk->signal = NULL;
- __exit_sighand(tsk);
- spin_unlock(&sighand->siglock);
- flush_sigqueue(&sig->shared_pending);
- } else {
- /*
- * If there is any task waiting for the group exit
- * then notify it:
- */
- if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
- wake_up_process(sig->group_exit_task);
- sig->group_exit_task = NULL;
- }
- if (tsk == sig->curr_target)
- sig->curr_target = NULL; // was: next_thread(tsk);
- tsk->signal = NULL;
- /*
- * Accumulate here the counters for all threads but the
- * group leader as they die, so they can be added into
- * the process-wide totals when those are taken.
- * The group leader stays around as a zombie as long
- * as there are other threads. When it gets reaped,
- * the exit.c code will add its counts into these totals.
- * We won't ever get here for the group leader, since it
- * will have been the last reference on the signal_struct.
- */
- sig->utime = cputime_add(sig->utime, tsk->utime);
- sig->stime = cputime_add(sig->stime, tsk->stime);
- sig->min_flt += tsk->min_flt;
- sig->maj_flt += tsk->maj_flt;
- sig->nvcsw += tsk->nvcsw;
- sig->nivcsw += tsk->nivcsw;
- sig->sched_time += tsk->sched_time;
- __exit_sighand(tsk);
- spin_unlock(&sighand->siglock);
- sig = NULL; /* Marker for below. */
- }
- rcu_read_unlock();
- clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
- flush_sigqueue(&tsk->pending);
- if (sig) {
- /*
- * We are cleaning up the signal_struct here.
- */
- exit_thread_group_keys(sig);
- kmem_cache_free(signal_cachep, sig);
- }
-}
-
-void exit_signal(struct task_struct *tsk)
-{
- atomic_dec(&tsk->signal->live);
-
- write_lock_irq(&tasklist_lock);
- __exit_signal(tsk);
- write_unlock_irq(&tasklist_lock);
-}
-
-/*
* Flush all handlers for a task.
*/
}
/* forward decl */
-static void do_notify_parent_cldstop(struct task_struct *tsk,
- int to_self,
- int why);
+static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
/*
* Handle magic process-wide effects of stop/continue signals.
p->signal->group_stop_count = 0;
p->signal->flags = SIGNAL_STOP_CONTINUED;
spin_unlock(&p->sighand->siglock);
- do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_STOPPED);
+ do_notify_parent_cldstop(p, CLD_STOPPED);
spin_lock(&p->sighand->siglock);
}
rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
p->signal->flags = SIGNAL_STOP_CONTINUED;
p->signal->group_exit_code = 0;
spin_unlock(&p->sighand->siglock);
- do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_CONTINUED);
+ do_notify_parent_cldstop(p, CLD_CONTINUED);
spin_lock(&p->sighand->siglock);
} else {
/*
{
int ret = 0;
- if (!irqs_disabled())
- BUG();
+ BUG_ON(!irqs_disabled());
assert_spin_locked(&t->sighand->siglock);
/* Short-circuit ignored signals. */
/*
* Must be called under rcu_read_lock() or with tasklist_lock read-held.
*/
+struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
+{
+ struct sighand_struct *sighand;
+
+ for (;;) {
+ sighand = rcu_dereference(tsk->sighand);
+ if (unlikely(sighand == NULL))
+ break;
+
+ spin_lock_irqsave(&sighand->siglock, *flags);
+ if (likely(sighand == tsk->sighand))
+ break;
+ spin_unlock_irqrestore(&sighand->siglock, *flags);
+ }
+
+ return sighand;
+}
+
int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
{
unsigned long flags;
- struct sighand_struct *sp;
int ret;
-retry:
ret = check_kill_permission(sig, info, p);
- if (!ret && sig && (sp = rcu_dereference(p->sighand))) {
- spin_lock_irqsave(&sp->siglock, flags);
- if (p->sighand != sp) {
- spin_unlock_irqrestore(&sp->siglock, flags);
- goto retry;
- }
- if ((atomic_read(&sp->count) == 0) ||
- (atomic_read(&p->usage) == 0)) {
- spin_unlock_irqrestore(&sp->siglock, flags);
- return -ESRCH;
+
+ if (!ret && sig) {
+ ret = -ESRCH;
+ if (lock_task_sighand(p, &flags)) {
+ ret = __group_send_sig_info(sig, info, p);
+ unlock_task_sighand(p, &flags);
}
- ret = __group_send_sig_info(sig, info, p);
- spin_unlock_irqrestore(&sp->siglock, flags);
}
return ret;
struct task_struct *p;
rcu_read_lock();
- if (unlikely(sig_kernel_stop(sig) || sig == SIGCONT)) {
+ if (unlikely(sig_needs_tasklist(sig))) {
read_lock(&tasklist_lock);
acquired_tasklist_lock = 1;
}
__sigqueue_free(q);
}
-int
-send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
+int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
{
unsigned long flags;
int ret = 0;
- struct sighand_struct *sh;
BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
*/
rcu_read_lock();
- if (unlikely(p->flags & PF_EXITING)) {
+ if (!likely(lock_task_sighand(p, &flags))) {
ret = -1;
goto out_err;
}
-retry:
- sh = rcu_dereference(p->sighand);
-
- spin_lock_irqsave(&sh->siglock, flags);
- if (p->sighand != sh) {
- /* We raced with exec() in a multithreaded process... */
- spin_unlock_irqrestore(&sh->siglock, flags);
- goto retry;
- }
-
- /*
- * We do the check here again to handle the following scenario:
- *
- * CPU 0 CPU 1
- * send_sigqueue
- * check PF_EXITING
- * interrupt exit code running
- * __exit_signal
- * lock sighand->siglock
- * unlock sighand->siglock
- * lock sh->siglock
- * add(tsk->pending) flush_sigqueue(tsk->pending)
- *
- */
-
- if (unlikely(p->flags & PF_EXITING)) {
- ret = -1;
- goto out;
- }
-
if (unlikely(!list_empty(&q->list))) {
/*
* If an SI_TIMER entry is already queue just increment
* the overrun count.
*/
- if (q->info.si_code != SI_TIMER)
- BUG();
+ BUG_ON(q->info.si_code != SI_TIMER);
q->info.si_overrun++;
goto out;
}
signal_wake_up(p, sig == SIGKILL);
out:
- spin_unlock_irqrestore(&sh->siglock, flags);
+ unlock_task_sighand(p, &flags);
out_err:
rcu_read_unlock();
* the overrun count. Other uses should not try to
* send the signal multiple times.
*/
- if (q->info.si_code != SI_TIMER)
- BUG();
+ BUG_ON(q->info.si_code != SI_TIMER);
q->info.si_overrun++;
goto out;
}
spin_unlock_irqrestore(&psig->siglock, flags);
}
-static void do_notify_parent_cldstop(struct task_struct *tsk, int to_self, int why)
+static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
{
struct siginfo info;
unsigned long flags;
struct task_struct *parent;
struct sighand_struct *sighand;
- if (to_self)
+ if (tsk->ptrace & PT_PTRACED)
parent = tsk->parent;
else {
tsk = tsk->group_leader;
!(current->ptrace & PT_ATTACHED)) &&
(likely(current->parent->signal != current->signal) ||
!unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))) {
- do_notify_parent_cldstop(current, 1, CLD_TRAPPED);
+ do_notify_parent_cldstop(current, CLD_TRAPPED);
read_unlock(&tasklist_lock);
schedule();
} else {
static void
finish_stop(int stop_count)
{
- int to_self;
-
/*
* If there are no other threads in the group, or if there is
* a group stop in progress and we are the last to stop,
* report to the parent. When ptraced, every thread reports itself.
*/
- if (stop_count < 0 || (current->ptrace & PT_PTRACED))
- to_self = 1;
- else if (stop_count == 0)
- to_self = 0;
- else
- goto out;
-
- read_lock(&tasklist_lock);
- do_notify_parent_cldstop(current, to_self, CLD_STOPPED);
- read_unlock(&tasklist_lock);
+ if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
+ read_lock(&tasklist_lock);
+ do_notify_parent_cldstop(current, CLD_STOPPED);
+ read_unlock(&tasklist_lock);
+ }
-out:
schedule();
/*
* Now we don't run again until continued.
* Returns nonzero if we've actually stopped and released the siglock.
* Returns zero if we didn't stop and still hold the siglock.
*/
-static int
-do_signal_stop(int signr)
+static int do_signal_stop(int signr)
{
struct signal_struct *sig = current->signal;
- struct sighand_struct *sighand = current->sighand;
- int stop_count = -1;
+ int stop_count;
if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED))
return 0;
* There is a group stop in progress. We don't need to
* start another one.
*/
- signr = sig->group_exit_code;
stop_count = --sig->group_stop_count;
- current->exit_code = signr;
- set_current_state(TASK_STOPPED);
- if (stop_count == 0)
- sig->flags = SIGNAL_STOP_STOPPED;
- spin_unlock_irq(&sighand->siglock);
- }
- else if (thread_group_empty(current)) {
- /*
- * Lock must be held through transition to stopped state.
- */
- current->exit_code = current->signal->group_exit_code = signr;
- set_current_state(TASK_STOPPED);
- sig->flags = SIGNAL_STOP_STOPPED;
- spin_unlock_irq(&sighand->siglock);
- }
- else {
+ } else {
/*
* There is no group stop already in progress.
- * We must initiate one now, but that requires
- * dropping siglock to get both the tasklist lock
- * and siglock again in the proper order. Note that
- * this allows an intervening SIGCONT to be posted.
- * We need to check for that and bail out if necessary.
+ * We must initiate one now.
*/
struct task_struct *t;
- spin_unlock_irq(&sighand->siglock);
-
- /* signals can be posted during this window */
-
- read_lock(&tasklist_lock);
- spin_lock_irq(&sighand->siglock);
+ sig->group_exit_code = signr;
- if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED)) {
+ stop_count = 0;
+ for (t = next_thread(current); t != current; t = next_thread(t))
/*
- * Another stop or continue happened while we
- * didn't have the lock. We can just swallow this
- * signal now. If we raced with a SIGCONT, that
- * should have just cleared it now. If we raced
- * with another processor delivering a stop signal,
- * then the SIGCONT that wakes us up should clear it.
+ * Setting state to TASK_STOPPED for a group
+ * stop is always done with the siglock held,
+ * so this check has no races.
*/
- read_unlock(&tasklist_lock);
- return 0;
- }
-
- if (sig->group_stop_count == 0) {
- sig->group_exit_code = signr;
- stop_count = 0;
- for (t = next_thread(current); t != current;
- t = next_thread(t))
- /*
- * Setting state to TASK_STOPPED for a group
- * stop is always done with the siglock held,
- * so this check has no races.
- */
- if (!t->exit_state &&
- !(t->state & (TASK_STOPPED|TASK_TRACED))) {
- stop_count++;
- signal_wake_up(t, 0);
- }
- sig->group_stop_count = stop_count;
- }
- else {
- /* A race with another thread while unlocked. */
- signr = sig->group_exit_code;
- stop_count = --sig->group_stop_count;
- }
-
- current->exit_code = signr;
- set_current_state(TASK_STOPPED);
- if (stop_count == 0)
- sig->flags = SIGNAL_STOP_STOPPED;
-
- spin_unlock_irq(&sighand->siglock);
- read_unlock(&tasklist_lock);
+ if (!t->exit_state &&
+ !(t->state & (TASK_STOPPED|TASK_TRACED))) {
+ stop_count++;
+ signal_wake_up(t, 0);
+ }
+ sig->group_stop_count = stop_count;
}
+ if (stop_count == 0)
+ sig->flags = SIGNAL_STOP_STOPPED;
+ current->exit_code = sig->group_exit_code;
+ __set_current_state(TASK_STOPPED);
+
+ spin_unlock_irq(¤t->sighand->siglock);
finish_stop(stop_count);
return 1;
}
sigset_t *mask = ¤t->blocked;
int signr = 0;
+ try_to_freeze();
+
relock:
spin_lock_irq(¤t->sighand->siglock);
for (;;) {
continue;
/* Init gets no signals it doesn't want. */
- if (current->pid == 1)
+ if (current == child_reaper)
continue;
if (sig_kernel_stop(signr)) {
EXPORT_SYMBOL(sigprocmask);
EXPORT_SYMBOL(block_all_signals);
EXPORT_SYMBOL(unblock_all_signals);
-EXPORT_SYMBOL_GPL(send_group_sig_info);
/*
int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
{
int error;
- sigset_t old_block;
spin_lock_irq(¤t->sighand->siglock);
- old_block = current->blocked;
+ if (oldset)
+ *oldset = current->blocked;
+
error = 0;
switch (how) {
case SIG_BLOCK:
}
recalc_sigpending();
spin_unlock_irq(¤t->sighand->siglock);
- if (oldset)
- *oldset = old_block;
+
return error;
}
timeout = schedule_timeout_interruptible(timeout);
- try_to_freeze();
spin_lock_irq(¤t->sighand->siglock);
sig = dequeue_signal(current, &these, &info);
current->blocked = current->real_blocked;
return kill_proc_info(sig, &info, pid);
}
-int
-do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
+int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
{
struct k_sigaction *k;
sigset_t mask;
if (act) {
sigdelsetmask(&act->sa.sa_mask,
sigmask(SIGKILL) | sigmask(SIGSTOP));
+ *k = *act;
/*
* POSIX 3.3.1.3:
* "Setting a signal action to SIG_IGN for a signal that is
* be discarded, whether or not it is blocked"
*/
if (act->sa.sa_handler == SIG_IGN ||
- (act->sa.sa_handler == SIG_DFL &&
- sig_kernel_ignore(sig))) {
- /*
- * This is a fairly rare case, so we only take the
- * tasklist_lock once we're sure we'll need it.
- * Now we must do this little unlock and relock
- * dance to maintain the lock hierarchy.
- */
+ (act->sa.sa_handler == SIG_DFL && sig_kernel_ignore(sig))) {
struct task_struct *t = current;
- spin_unlock_irq(&t->sighand->siglock);
- read_lock(&tasklist_lock);
- spin_lock_irq(&t->sighand->siglock);
- *k = *act;
sigemptyset(&mask);
sigaddset(&mask, sig);
rm_from_queue_full(&mask, &t->signal->shared_pending);
recalc_sigpending_tsk(t);
t = next_thread(t);
} while (t != current);
- spin_unlock_irq(¤t->sighand->siglock);
- read_unlock(&tasklist_lock);
- return 0;
}
-
- *k = *act;
}
spin_unlock_irq(¤t->sighand->siglock);
__alignof__(struct sigqueue),
SLAB_PANIC, NULL, NULL);
}
-
-#ifdef CONFIG_KDB
-#include <linux/kdb.h>
-/*
- * kdb_send_sig_info
- *
- * Allows kdb to send signals without exposing signal internals.
- *
- * Inputs:
- * t task
- * siginfo signal information
- * seqno current kdb sequence number (avoid including kdbprivate.h)
- * Outputs:
- * None.
- * Returns:
- * None.
- * Locking:
- * Checks if the required locks are available before calling the main
- * signal code, to avoid kdb deadlocks.
- * Remarks:
- */
-void
-kdb_send_sig_info(struct task_struct *t, struct siginfo *info, int seqno)
-{
- static struct task_struct *kdb_prev_t;
- static int kdb_prev_seqno;
- int sig, new_t;
- if (!spin_trylock(&t->sighand->siglock)) {
- kdb_printf("Can't do kill command now.\n"
- "The sigmask lock is held somewhere else in kernel, try again later\n");
- return;
- }
- spin_unlock(&t->sighand->siglock);
- new_t = kdb_prev_t != t || kdb_prev_seqno != seqno;
- kdb_prev_t = t;
- kdb_prev_seqno = seqno;
- if (t->state != TASK_RUNNING && new_t) {
- kdb_printf("Process is not RUNNING, sending a signal from kdb risks deadlock\n"
- "on the run queue locks. The signal has _not_ been sent.\n"
- "Reissue the kill command if you want to risk the deadlock.\n");
- return;
- }
- sig = info->si_signo;
- if (send_sig_info(sig, info, t))
- kdb_printf("Fail to deliver Signal %d to process %d.\n", sig, t->pid);
- else
- kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
-}
-#endif /* CONFIG_KDB */
projects / linux-flexiantxendom0-3.2.10.git / blobdiff