diff options
Diffstat (limited to 'kernel/signal.c')
| -rw-r--r-- | kernel/signal.c | 821 |
1 files changed, 559 insertions, 262 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index 324eff5468ad..ad5e818baacc 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -124,7 +124,7 @@ static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked) static int recalc_sigpending_tsk(struct task_struct *t) { - if (t->signal->group_stop_count > 0 || + if ((t->group_stop & GROUP_STOP_PENDING) || PENDING(&t->pending, &t->blocked) || PENDING(&t->signal->shared_pending, &t->blocked)) { set_tsk_thread_flag(t, TIF_SIGPENDING); @@ -223,10 +223,87 @@ static inline void print_dropped_signal(int sig) current->comm, current->pid, sig); } +/** + * task_clear_group_stop_trapping - clear group stop trapping bit + * @task: target task + * + * If GROUP_STOP_TRAPPING is set, a ptracer is waiting for us. Clear it + * and wake up the ptracer. Note that we don't need any further locking. + * @task->siglock guarantees that @task->parent points to the ptracer. + * + * CONTEXT: + * Must be called with @task->sighand->siglock held. + */ +static void task_clear_group_stop_trapping(struct task_struct *task) +{ + if (unlikely(task->group_stop & GROUP_STOP_TRAPPING)) { + task->group_stop &= ~GROUP_STOP_TRAPPING; + __wake_up_sync_key(&task->parent->signal->wait_chldexit, + TASK_UNINTERRUPTIBLE, 1, task); + } +} + +/** + * task_clear_group_stop_pending - clear pending group stop + * @task: target task + * + * Clear group stop states for @task. + * + * CONTEXT: + * Must be called with @task->sighand->siglock held. + */ +void task_clear_group_stop_pending(struct task_struct *task) +{ + task->group_stop &= ~(GROUP_STOP_PENDING | GROUP_STOP_CONSUME | + GROUP_STOP_DEQUEUED); +} + +/** + * task_participate_group_stop - participate in a group stop + * @task: task participating in a group stop + * + * @task has GROUP_STOP_PENDING set and is participating in a group stop. + * Group stop states are cleared and the group stop count is consumed if + * %GROUP_STOP_CONSUME was set. If the consumption completes the group + * stop, the appropriate %SIGNAL_* flags are set. + * + * CONTEXT: + * Must be called with @task->sighand->siglock held. + * + * RETURNS: + * %true if group stop completion should be notified to the parent, %false + * otherwise. + */ +static bool task_participate_group_stop(struct task_struct *task) +{ + struct signal_struct *sig = task->signal; + bool consume = task->group_stop & GROUP_STOP_CONSUME; + + WARN_ON_ONCE(!(task->group_stop & GROUP_STOP_PENDING)); + + task_clear_group_stop_pending(task); + + if (!consume) + return false; + + if (!WARN_ON_ONCE(sig->group_stop_count == 0)) + sig->group_stop_count--; + + /* + * Tell the caller to notify completion iff we are entering into a + * fresh group stop. Read comment in do_signal_stop() for details. + */ + if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) { + sig->flags = SIGNAL_STOP_STOPPED; + return true; + } + return false; +} + /* * allocate a new signal queue record * - this may be called without locks if and only if t == current, otherwise an - * appopriate lock must be held to stop the target task from exiting + * appropriate lock must be held to stop the target task from exiting */ static struct sigqueue * __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit) @@ -375,15 +452,15 @@ int unhandled_signal(struct task_struct *tsk, int sig) return !tracehook_consider_fatal_signal(tsk, sig); } - -/* Notify the system that a driver wants to block all signals for this +/* + * Notify the system that a driver wants to block all signals for this * process, and wants to be notified if any signals at all were to be * sent/acted upon. If the notifier routine returns non-zero, then the * signal will be acted upon after all. If the notifier routine returns 0, * then then signal will be blocked. Only one block per process is * allowed. priv is a pointer to private data that the notifier routine - * can use to determine if the signal should be blocked or not. */ - + * can use to determine if the signal should be blocked or not. + */ void block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask) { @@ -434,9 +511,10 @@ still_pending: copy_siginfo(info, &first->info); __sigqueue_free(first); } else { - /* Ok, it wasn't in the queue. This must be - a fast-pathed signal or we must have been - out of queue space. So zero out the info. + /* + * Ok, it wasn't in the queue. This must be + * a fast-pathed signal or we must have been + * out of queue space. So zero out the info. */ info->si_signo = sig; info->si_errno = 0; @@ -468,7 +546,7 @@ static int __dequeue_signal(struct sigpending *pending, sigset_t *mask, } /* - * Dequeue a signal and return the element to the caller, which is + * Dequeue a signal and return the element to the caller, which is * expected to free it. * * All callers have to hold the siglock. @@ -490,7 +568,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) * itimers are process shared and we restart periodic * itimers in the signal delivery path to prevent DoS * attacks in the high resolution timer case. This is - * compliant with the old way of self restarting + * compliant with the old way of self-restarting * itimers, as the SIGALRM is a legacy signal and only * queued once. Changing the restart behaviour to * restart the timer in the signal dequeue path is @@ -526,7 +604,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) * is to alert stop-signal processing code when another * processor has come along and cleared the flag. */ - tsk->signal->flags |= SIGNAL_STOP_DEQUEUED; + current->group_stop |= GROUP_STOP_DEQUEUED; } if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) { /* @@ -591,7 +669,7 @@ static int rm_from_queue_full(sigset_t *mask, struct sigpending *s) if (sigisemptyset(&m)) return 0; - signandsets(&s->signal, &s->signal, mask); + sigandnsets(&s->signal, &s->signal, mask); list_for_each_entry_safe(q, n, &s->list, list) { if (sigismember(mask, q->info.si_signo)) { list_del_init(&q->list); @@ -726,34 +804,14 @@ static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns) } else if (sig == SIGCONT) { unsigned int why; /* - * Remove all stop signals from all queues, - * and wake all threads. + * Remove all stop signals from all queues, wake all threads. */ rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending); t = p; do { - unsigned int state; + task_clear_group_stop_pending(t); rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending); - /* - * If there is a handler for SIGCONT, we must make - * sure that no thread returns to user mode before - * we post the signal, in case it was the only - * thread eligible to run the signal handler--then - * it must not do anything between resuming and - * running the handler. With the TIF_SIGPENDING - * flag set, the thread will pause and acquire the - * siglock that we hold now and until we've queued - * the pending signal. - * - * Wake up the stopped thread _after_ setting - * TIF_SIGPENDING - */ - state = __TASK_STOPPED; - if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) { - set_tsk_thread_flag(t, TIF_SIGPENDING); - state |= TASK_INTERRUPTIBLE; - } - wake_up_state(t, state); + wake_up_state(t, __TASK_STOPPED); } while_each_thread(p, t); /* @@ -779,13 +837,6 @@ static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns) signal->flags = why | SIGNAL_STOP_CONTINUED; signal->group_stop_count = 0; signal->group_exit_code = 0; - } else { - /* - * We are not stopped, but there could be a stop - * signal in the middle of being processed after - * being removed from the queue. Clear that too. - */ - signal->flags &= ~SIGNAL_STOP_DEQUEUED; } } @@ -874,6 +925,7 @@ static void complete_signal(int sig, struct task_struct *p, int group) signal->group_stop_count = 0; t = p; do { + task_clear_group_stop_pending(t); sigaddset(&t->pending.signal, SIGKILL); signal_wake_up(t, 1); } while_each_thread(p, t); @@ -923,14 +975,15 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, if (info == SEND_SIG_FORCED) goto out_set; - /* Real-time signals must be queued if sent by sigqueue, or - some other real-time mechanism. It is implementation - defined whether kill() does so. We attempt to do so, on - the principle of least surprise, but since kill is not - allowed to fail with EAGAIN when low on memory we just - make sure at least one signal gets delivered and don't - pass on the info struct. */ - + /* + * Real-time signals must be queued if sent by sigqueue, or + * some other real-time mechanism. It is implementation + * defined whether kill() does so. We attempt to do so, on + * the principle of least surprise, but since kill is not + * allowed to fail with EAGAIN when low on memory we just + * make sure at least one signal gets delivered and don't + * pass on the info struct. + */ if (sig < SIGRTMIN) override_rlimit = (is_si_special(info) || info->si_code >= 0); else @@ -1107,6 +1160,7 @@ int zap_other_threads(struct task_struct *p) p->signal->group_stop_count = 0; while_each_thread(p, t) { + task_clear_group_stop_pending(t); count++; /* Don't bother with already dead threads */ @@ -1201,8 +1255,7 @@ retry: return error; } -int -kill_proc_info(int sig, struct siginfo *info, pid_t pid) +int kill_proc_info(int sig, struct siginfo *info, pid_t pid) { int error; rcu_read_lock(); @@ -1299,8 +1352,7 @@ static int kill_something_info(int sig, struct siginfo *info, pid_t pid) * These are for backward compatibility with the rest of the kernel source. */ -int -send_sig_info(int sig, struct siginfo *info, struct task_struct *p) +int send_sig_info(int sig, struct siginfo *info, struct task_struct *p) { /* * Make sure legacy kernel users don't send in bad values @@ -1368,7 +1420,7 @@ EXPORT_SYMBOL(kill_pid); * These functions support sending signals using preallocated sigqueue * structures. This is needed "because realtime applications cannot * afford to lose notifications of asynchronous events, like timer - * expirations or I/O completions". In the case of Posix Timers + * expirations or I/O completions". In the case of POSIX Timers * we allocate the sigqueue structure from the timer_create. If this * allocation fails we are able to report the failure to the application * with an EAGAIN error. @@ -1536,16 +1588,30 @@ int do_notify_parent(struct task_struct *tsk, int sig) return ret; } -static void do_notify_parent_cldstop(struct task_struct *tsk, int why) +/** + * do_notify_parent_cldstop - notify parent of stopped/continued state change + * @tsk: task reporting the state change + * @for_ptracer: the notification is for ptracer + * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report + * + * Notify @tsk's parent that the stopped/continued state has changed. If + * @for_ptracer is %false, @tsk's group leader notifies to its real parent. + * If %true, @tsk reports to @tsk->parent which should be the ptracer. + * + * CONTEXT: + * Must be called with tasklist_lock at least read locked. + */ +static void do_notify_parent_cldstop(struct task_struct *tsk, + bool for_ptracer, int why) { struct siginfo info; unsigned long flags; struct task_struct *parent; struct sighand_struct *sighand; - if (task_ptrace(tsk)) + if (for_ptracer) { parent = tsk->parent; - else { + } else { tsk = tsk->group_leader; parent = tsk->real_parent; } @@ -1553,7 +1619,7 @@ static void do_notify_parent_cldstop(struct task_struct *tsk, int why) info.si_signo = SIGCHLD; info.si_errno = 0; /* - * see comment in do_notify_parent() abot the following 3 lines + * see comment in do_notify_parent() about the following 4 lines */ rcu_read_lock(); info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns); @@ -1611,7 +1677,7 @@ static inline int may_ptrace_stop(void) } /* - * Return nonzero if there is a SIGKILL that should be waking us up. + * Return non-zero if there is a SIGKILL that should be waking us up. * Called with the siglock held. */ static int sigkill_pending(struct task_struct *tsk) @@ -1621,6 +1687,15 @@ static int sigkill_pending(struct task_struct *tsk) } /* + * Test whether the target task of the usual cldstop notification - the + * real_parent of @child - is in the same group as the ptracer. + */ +static bool real_parent_is_ptracer(struct task_struct *child) +{ + return same_thread_group(child->parent, child->real_parent); +} + +/* * This must be called with current->sighand->siglock held. * * This should be the path for all ptrace stops. @@ -1631,10 +1706,12 @@ static int sigkill_pending(struct task_struct *tsk) * If we actually decide not to stop at all because the tracer * is gone, we keep current->exit_code unless clear_code. */ -static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info) +static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) __releases(¤t->sighand->siglock) __acquires(¤t->sighand->siglock) { + bool gstop_done = false; + if (arch_ptrace_stop_needed(exit_code, info)) { /* * The arch code has something special to do before a @@ -1655,21 +1732,49 @@ static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info) } /* - * If there is a group stop in progress, - * we must participate in the bookkeeping. + * If @why is CLD_STOPPED, we're trapping to participate in a group + * stop. Do the bookkeeping. Note that if SIGCONT was delievered + * while siglock was released for the arch hook, PENDING could be + * clear now. We act as if SIGCONT is received after TASK_TRACED + * is entered - ignore it. */ - if (current->signal->group_stop_count > 0) - --current->signal->group_stop_count; + if (why == CLD_STOPPED && (current->group_stop & GROUP_STOP_PENDING)) + gstop_done = task_participate_group_stop(current); current->last_siginfo = info; current->exit_code = exit_code; - /* Let the debugger run. */ - __set_current_state(TASK_TRACED); + /* + * TRACED should be visible before TRAPPING is cleared; otherwise, + * the tracer might fail do_wait(). + */ + set_current_state(TASK_TRACED); + + /* + * We're committing to trapping. Clearing GROUP_STOP_TRAPPING and + * transition to TASK_TRACED should be atomic with respect to + * siglock. This hsould be done after the arch hook as siglock is + * released and regrabbed across it. + */ + task_clear_group_stop_trapping(current); + spin_unlock_irq(¤t->sighand->siglock); read_lock(&tasklist_lock); if (may_ptrace_stop()) { - do_notify_parent_cldstop(current, CLD_TRAPPED); + /* + * Notify parents of the stop. + * + * While ptraced, there are two parents - the ptracer and + * the real_parent of the group_leader. The ptracer should + * know about every stop while the real parent is only + * interested in the completion of group stop. The states + * for the two don't interact with each other. Notify + * separately unless they're gonna be duplicates. + */ + do_notify_parent_cldstop(current, true, why); + if (gstop_done && !real_parent_is_ptracer(current)) + do_notify_parent_cldstop(current, false, why); + /* * Don't want to allow preemption here, because * sys_ptrace() needs this task to be inactive. @@ -1684,7 +1789,16 @@ static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info) /* * By the time we got the lock, our tracer went away. * Don't drop the lock yet, another tracer may come. + * + * If @gstop_done, the ptracer went away between group stop + * completion and here. During detach, it would have set + * GROUP_STOP_PENDING on us and we'll re-enter TASK_STOPPED + * in do_signal_stop() on return, so notifying the real + * parent of the group stop completion is enough. */ + if (gstop_done) + do_notify_parent_cldstop(current, false, why); + __set_current_state(TASK_RUNNING); if (clear_code) current->exit_code = 0; @@ -1728,79 +1842,128 @@ void ptrace_notify(int exit_code) /* Let the debugger run. */ spin_lock_irq(¤t->sighand->siglock); - ptrace_stop(exit_code, 1, &info); + ptrace_stop(exit_code, CLD_TRAPPED, 1, &info); spin_unlock_irq(¤t->sighand->siglock); } /* * This performs the stopping for SIGSTOP and other stop signals. * We have to stop all threads in the thread group. - * Returns nonzero if we've actually stopped and released the siglock. + * Returns non-zero 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) { struct signal_struct *sig = current->signal; - int notify; - if (!sig->group_stop_count) { + if (!(current->group_stop & GROUP_STOP_PENDING)) { + unsigned int gstop = GROUP_STOP_PENDING | GROUP_STOP_CONSUME; struct task_struct *t; - if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) || + /* signr will be recorded in task->group_stop for retries */ + WARN_ON_ONCE(signr & ~GROUP_STOP_SIGMASK); + + if (!likely(current->group_stop & GROUP_STOP_DEQUEUED) || unlikely(signal_group_exit(sig))) return 0; /* - * There is no group stop already in progress. - * We must initiate one now. + * There is no group stop already in progress. We must + * initiate one now. + * + * While ptraced, a task may be resumed while group stop is + * still in effect and then receive a stop signal and + * initiate another group stop. This deviates from the + * usual behavior as two consecutive stop signals can't + * cause two group stops when !ptraced. That is why we + * also check !task_is_stopped(t) below. + * + * The condition can be distinguished by testing whether + * SIGNAL_STOP_STOPPED is already set. Don't generate + * group_exit_code in such case. + * + * This is not necessary for SIGNAL_STOP_CONTINUED because + * an intervening stop signal is required to cause two + * continued events regardless of ptrace. */ - sig->group_exit_code = signr; + if (!(sig->flags & SIGNAL_STOP_STOPPED)) + sig->group_exit_code = signr; + else + WARN_ON_ONCE(!task_ptrace(current)); + current->group_stop &= ~GROUP_STOP_SIGMASK; + current->group_stop |= signr | gstop; sig->group_stop_count = 1; - for (t = next_thread(current); t != current; t = next_thread(t)) + for (t = next_thread(current); t != current; + t = next_thread(t)) { + t->group_stop &= ~GROUP_STOP_SIGMASK; /* * Setting state to TASK_STOPPED for a group * stop is always done with the siglock held, * so this check has no races. */ - if (!(t->flags & PF_EXITING) && - !task_is_stopped_or_traced(t)) { + if (!(t->flags & PF_EXITING) && !task_is_stopped(t)) { + t->group_stop |= signr | gstop; sig->group_stop_count++; signal_wake_up(t, 0); } + } } - /* - * 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. - */ - notify = sig->group_stop_count == 1 ? CLD_STOPPED : 0; - notify = tracehook_notify_jctl(notify, CLD_STOPPED); - /* - * tracehook_notify_jctl() can drop and reacquire siglock, so - * we keep ->group_stop_count != 0 before the call. If SIGCONT - * or SIGKILL comes in between ->group_stop_count == 0. - */ - if (sig->group_stop_count) { - if (!--sig->group_stop_count) - sig->flags = SIGNAL_STOP_STOPPED; - current->exit_code = sig->group_exit_code; +retry: + if (likely(!task_ptrace(current))) { + int notify = 0; + + /* + * 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. + */ + if (task_participate_group_stop(current)) + notify = CLD_STOPPED; + __set_current_state(TASK_STOPPED); + spin_unlock_irq(¤t->sighand->siglock); + + /* + * Notify the parent of the group stop completion. Because + * we're not holding either the siglock or tasklist_lock + * here, ptracer may attach inbetween; however, this is for + * group stop and should always be delivered to the real + * parent of the group leader. The new ptracer will get + * its notification when this task transitions into + * TASK_TRACED. + */ + if (notify) { + read_lock(&tasklist_lock); + do_notify_parent_cldstop(current, false, notify); + read_unlock(&tasklist_lock); + } + + /* Now we don't run again until woken by SIGCONT or SIGKILL */ + schedule(); + + spin_lock_irq(¤t->sighand->siglock); + } else { + ptrace_stop(current->group_stop & GROUP_STOP_SIGMASK, + CLD_STOPPED, 0, NULL); + current->exit_code = 0; } - spin_unlock_irq(¤t->sighand->siglock); - if (notify) { - read_lock(&tasklist_lock); - do_notify_parent_cldstop(current, notify); - read_unlock(&tasklist_lock); + /* + * GROUP_STOP_PENDING could be set if another group stop has + * started since being woken up or ptrace wants us to transit + * between TASK_STOPPED and TRACED. Retry group stop. + */ + if (current->group_stop & GROUP_STOP_PENDING) { + WARN_ON_ONCE(!(current->group_stop & GROUP_STOP_SIGMASK)); + goto retry; } - /* Now we don't run again until woken by SIGCONT or SIGKILL */ - do { - schedule(); - } while (try_to_freeze()); + /* PTRACE_ATTACH might have raced with task killing, clear trapping */ + task_clear_group_stop_trapping(current); + + spin_unlock_irq(¤t->sighand->siglock); tracehook_finish_jctl(); - current->exit_code = 0; return 1; } @@ -1814,7 +1977,7 @@ static int ptrace_signal(int signr, siginfo_t *info, ptrace_signal_deliver(regs, cookie); /* Let the debugger run. */ - ptrace_stop(signr, 0, info); + ptrace_stop(signr, CLD_TRAPPED, 0, info); /* We're back. Did the debugger cancel the sig? */ signr = current->exit_code; @@ -1823,10 +1986,12 @@ static int ptrace_signal(int signr, siginfo_t *info, current->exit_code = 0; - /* Update the siginfo structure if the signal has - changed. If the debugger wanted something - specific in the siginfo structure then it should - have updated *info via PTRACE_SETSIGINFO. */ + /* + * Update the siginfo structure if the signal has + * changed. If the debugger wanted something + * specific in the siginfo structure then it should + * have updated *info via PTRACE_SETSIGINFO. + */ if (signr != info->si_signo) { info->si_signo = signr; info->si_errno = 0; @@ -1867,25 +2032,43 @@ relock: * the CLD_ si_code into SIGNAL_CLD_MASK bits. */ if (unlikely(signal->flags & SIGNAL_CLD_MASK)) { - int why = (signal->flags & SIGNAL_STOP_CONTINUED) - ? CLD_CONTINUED : CLD_STOPPED; + struct task_struct *leader; + int why; + + if (signal->flags & SIGNAL_CLD_CONTINUED) + why = CLD_CONTINUED; + else + why = CLD_STOPPED; + signal->flags &= ~SIGNAL_CLD_MASK; - why = tracehook_notify_jctl(why, CLD_CONTINUED); spin_unlock_irq(&sighand->siglock); - if (why) { - read_lock(&tasklist_lock); - do_notify_parent_cldstop(current->group_leader, why); - read_unlock(&tasklist_lock); - } + /* + * Notify the parent that we're continuing. This event is + * always per-process and doesn't make whole lot of sense + * for ptracers, who shouldn't consume the state via + * wait(2) either, but, for backward compatibility, notify + * the ptracer of the group leader too unless it's gonna be + * a duplicate. + */ + read_lock(&tasklist_lock); + + do_notify_parent_cldstop(current, false, why); + + leader = current->group_leader; + if (task_ptrace(leader) && !real_parent_is_ptracer(leader)) + do_notify_parent_cldstop(leader, true, why); + + read_unlock(&tasklist_lock); + goto relock; } for (;;) { struct k_sigaction *ka; /* - * Tracing can induce an artifical signal and choose sigaction. + * Tracing can induce an artificial signal and choose sigaction. * The return value in @signr determines the default action, * but @info->si_signo is the signal number we will report. */ @@ -1895,8 +2078,8 @@ relock: if (unlikely(signr != 0)) ka = return_ka; else { - if (unlikely(signal->group_stop_count > 0) && - do_signal_stop(0)) + if (unlikely(current->group_stop & + GROUP_STOP_PENDING) && do_signal_stop(0)) goto relock; signr = dequeue_signal(current, ¤t->blocked, @@ -2015,10 +2198,42 @@ relock: return signr; } +/* + * It could be that complete_signal() picked us to notify about the + * group-wide signal. Other threads should be notified now to take + * the shared signals in @which since we will not. + */ +static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which) +{ + sigset_t retarget; + struct task_struct *t; + + sigandsets(&retarget, &tsk->signal->shared_pending.signal, which); + if (sigisemptyset(&retarget)) + return; + + t = tsk; + while_each_thread(tsk, t) { + if (t->flags & PF_EXITING) + continue; + + if (!has_pending_signals(&retarget, &t->blocked)) + continue; + /* Remove the signals this thread can handle. */ + sigandsets(&retarget, &retarget, &t->blocked); + + if (!signal_pending(t)) + signal_wake_up(t, 0); + + if (sigisemptyset(&retarget)) + break; + } +} + void exit_signals(struct task_struct *tsk) { int group_stop = 0; - struct task_struct *t; + sigset_t unblocked; if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) { tsk->flags |= PF_EXITING; @@ -2034,25 +2249,23 @@ void exit_signals(struct task_struct *tsk) if (!signal_pending(tsk)) goto out; - /* It could be that __group_complete_signal() choose us to - * notify about group-wide signal. Another thread should be - * woken now to take the signal since we will not. - */ - for (t = tsk; (t = next_thread(t)) != tsk; ) - if (!signal_pending(t) && !(t->flags & PF_EXITING)) - recalc_sigpending_and_wake(t); + unblocked = tsk->blocked; + signotset(&unblocked); + retarget_shared_pending(tsk, &unblocked); - if (unlikely(tsk->signal->group_stop_count) && - !--tsk->signal->group_stop_count) { - tsk->signal->flags = SIGNAL_STOP_STOPPED; - group_stop = tracehook_notify_jctl(CLD_STOPPED, CLD_STOPPED); - } + if (unlikely(tsk->group_stop & GROUP_STOP_PENDING) && + task_participate_group_stop(tsk)) + group_stop = CLD_STOPPED; out: spin_unlock_irq(&tsk->sighand->siglock); + /* + * If group stop has completed, deliver the notification. This + * should always go to the real parent of the group leader. + */ if (unlikely(group_stop)) { read_lock(&tasklist_lock); - do_notify_parent_cldstop(tsk, group_stop); + do_notify_parent_cldstop(tsk, false, group_stop); read_unlock(&tasklist_lock); } } @@ -2072,6 +2285,9 @@ EXPORT_SYMBOL(unblock_all_signals); * System call entry points. */ +/** + * sys_restart_syscall - restart a system call + */ SYSCALL_DEFINE0(restart_syscall) { struct restart_block *restart = ¤t_thread_info()->restart_block; @@ -2083,11 +2299,33 @@ long do_no_restart_syscall(struct restart_block *param) return -EINTR; } -/* - * We don't need to get the kernel lock - this is all local to this - * particular thread.. (and that's good, because this is _heavily_ - * used by various programs) +static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset) +{ + if (signal_pending(tsk) && !thread_group_empty(tsk)) { + sigset_t newblocked; + /* A set of now blocked but previously unblocked signals. */ + sigandnsets(&newblocked, newset, ¤t->blocked); + retarget_shared_pending(tsk, &newblocked); + } + tsk->blocked = *newset; + recalc_sigpending(); +} + +/** + * set_current_blocked - change current->blocked mask + * @newset: new mask + * + * It is wrong to change ->blocked directly, this helper should be used + * to ensure the process can't miss a shared signal we are going to block. */ +void set_current_blocked(const sigset_t *newset) +{ + struct task_struct *tsk = current; + + spin_lock_irq(&tsk->sighand->siglock); + __set_task_blocked(tsk, newset); + spin_unlock_irq(&tsk->sighand->siglock); +} /* * This is also useful for kernel threads that want to temporarily @@ -2099,66 +2337,66 @@ long do_no_restart_syscall(struct restart_block *param) */ int sigprocmask(int how, sigset_t *set, sigset_t *oldset) { - int error; + struct task_struct *tsk = current; + sigset_t newset; - spin_lock_irq(¤t->sighand->siglock); + /* Lockless, only current can change ->blocked, never from irq */ if (oldset) - *oldset = current->blocked; + *oldset = tsk->blocked; - error = 0; switch (how) { case SIG_BLOCK: - sigorsets(¤t->blocked, ¤t->blocked, set); + sigorsets(&newset, &tsk->blocked, set); break; case SIG_UNBLOCK: - signandsets(¤t->blocked, ¤t->blocked, set); + sigandnsets(&newset, &tsk->blocked, set); break; case SIG_SETMASK: - current->blocked = *set; + newset = *set; break; default: - error = -EINVAL; + return -EINVAL; } - recalc_sigpending(); - spin_unlock_irq(¤t->sighand->siglock); - return error; + set_current_blocked(&newset); + return 0; } -SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, set, +/** + * sys_rt_sigprocmask - change the list of currently blocked signals + * @how: whether to add, remove, or set signals + * @set: stores pending signals + * @oset: previous value of signal mask if non-null + * @sigsetsize: size of sigset_t type + */ +SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset, sigset_t __user *, oset, size_t, sigsetsize) { - int error = -EINVAL; sigset_t old_set, new_set; + int error; /* XXX: Don't preclude handling different sized sigset_t's. */ if (sigsetsize != sizeof(sigset_t)) - goto out; + return -EINVAL; - if (set) { - error = -EFAULT; - if (copy_from_user(&new_set, set, sizeof(*set))) - goto out; + old_set = current->blocked; + + if (nset) { + if (copy_from_user(&new_set, nset, sizeof(sigset_t))) + return -EFAULT; sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); - error = sigprocmask(how, &new_set, &old_set); + error = sigprocmask(how, &new_set, NULL); if (error) - goto out; - if (oset) - goto set_old; - } else if (oset) { - spin_lock_irq(¤t->sighand->siglock); - old_set = current->blocked; - spin_unlock_irq(¤t->sighand->siglock); + return error; + } - set_old: - error = -EFAULT; - if (copy_to_user(oset, &old_set, sizeof(*oset))) - goto out; + if (oset) { + if (copy_to_user(oset, &old_set, sizeof(sigset_t))) + return -EFAULT; } - error = 0; -out: - return error; + + return 0; } long do_sigpending(void __user *set, unsigned long sigsetsize) @@ -2183,8 +2421,14 @@ long do_sigpending(void __user *set, unsigned long sigsetsize) out: return error; -} +} +/** + * sys_rt_sigpending - examine a pending signal that has been raised + * while blocked + * @set: stores pending signals + * @sigsetsize: size of sigset_t type or larger + */ SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize) { return do_sigpending(set, sigsetsize); @@ -2233,9 +2477,9 @@ int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from) err |= __put_user(from->si_trapno, &to->si_trapno); #endif #ifdef BUS_MCEERR_AO - /* + /* * Other callers might not initialize the si_lsb field, - * so check explicitely for the right codes here. + * so check explicitly for the right codes here. */ if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO) err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb); @@ -2264,15 +2508,82 @@ int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from) #endif +/** + * do_sigtimedwait - wait for queued signals specified in @which + * @which: queued signals to wait for + * @info: if non-null, the signal's siginfo is returned here + * @ts: upper bound on process time suspension + */ +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. Unblocking is always fine, we can avoid + * set_current_blocked(). + */ + 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); + __set_task_blocked(tsk, &tsk->real_blocked); + siginitset(&tsk->real_blocked, 0); + sig = dequeue_signal(tsk, &mask, info); + } + 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 + * @uthese: queued signals to wait for + * @uinfo: if non-null, the signal's siginfo is returned here + * @uts: upper bound on process time suspension + * @sigsetsize: size of sigset_t type + */ SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese, 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 = 0; + int ret; /* XXX: Don't preclude handling different sized sigset_t's. */ if (sigsetsize != sizeof(sigset_t)) @@ -2280,65 +2591,27 @@ SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese, 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); if (uts) { if (copy_from_user(&ts, uts, sizeof(ts))) return -EFAULT; - if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0 - || ts.tv_sec < 0) - return -EINVAL; } - spin_lock_irq(¤t->sighand->siglock); - sig = dequeue_signal(current, &these, &info); - if (!sig) { - timeout = MAX_SCHEDULE_TIMEOUT; - if (uts) - timeout = (timespec_to_jiffies(&ts) - + (ts.tv_sec || ts.tv_nsec)); - - if (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(¤t->blocked, ¤t->blocked, &these); - recalc_sigpending(); - spin_unlock_irq(¤t->sighand->siglock); - - timeout = schedule_timeout_interruptible(timeout); - - spin_lock_irq(¤t->sighand->siglock); - sig = dequeue_signal(current, &these, &info); - current->blocked = current->real_blocked; - siginitset(¤t->real_blocked, 0); - recalc_sigpending(); - } - } - spin_unlock_irq(¤t->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; } +/** + * sys_kill - send a signal to a process + * @pid: the PID of the process + * @sig: signal to be sent + */ SYSCALL_DEFINE2(kill, pid_t, pid, int, sig) { struct siginfo info; @@ -2414,7 +2687,11 @@ SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig) return do_tkill(tgid, pid, sig); } -/* +/** + * sys_tkill - send signal to one specific task + * @pid: the PID of the task + * @sig: signal to be sent + * * Send a signal to only one task, even if it's a CLONE_THREAD task. */ SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig) @@ -2426,6 +2703,12 @@ SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig) return do_tkill(0, pid, sig); } +/** + * sys_rt_sigqueueinfo - send signal information to a signal + * @pid: the PID of the thread + * @sig: signal to be sent + * @uinfo: signal info to be sent + */ SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig, siginfo_t __user *, uinfo) { @@ -2437,7 +2720,7 @@ SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig, /* Not even root can pretend to send signals from the kernel. * Nor can they impersonate a kill()/tgkill(), which adds source info. */ - if (info.si_code != SI_QUEUE) { + if (info.si_code >= 0 || info.si_code == SI_TKILL) { /* We used to allow any < 0 si_code */ WARN_ON_ONCE(info.si_code < 0); return -EPERM; @@ -2457,7 +2740,7 @@ long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info) /* Not even root can pretend to send signals from the kernel. * Nor can they impersonate a kill()/tgkill(), which adds source info. */ - if (info->si_code != SI_QUEUE) { + if (info->si_code >= 0 || info->si_code == SI_TKILL) { /* We used to allow any < 0 si_code */ WARN_ON_ONCE(info->si_code < 0); return -EPERM; @@ -2553,12 +2836,11 @@ do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long s error = -EINVAL; /* - * - * Note - this code used to test ss_flags incorrectly + * Note - this code used to test ss_flags incorrectly: * old code may have been written using ss_flags==0 * to mean ss_flags==SS_ONSTACK (as this was the only * way that worked) - this fix preserves that older - * mechanism + * mechanism. */ if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0) goto out; @@ -2592,6 +2874,10 @@ out: #ifdef __ARCH_WANT_SYS_SIGPENDING +/** + * sys_sigpending - examine pending signals + * @set: where mask of pending signal is returned + */ SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set) { return do_sigpending(set, sizeof(*set)); @@ -2600,60 +2886,65 @@ SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set) #endif #ifdef __ARCH_WANT_SYS_SIGPROCMASK -/* Some platforms have their own version with special arguments others - support only sys_rt_sigprocmask. */ +/** + * sys_sigprocmask - examine and change blocked signals + * @how: whether to add, remove, or set signals + * @nset: signals to add or remove (if non-null) + * @oset: previous value of signal mask if non-null + * + * Some platforms have their own version with special arguments; + * others support only sys_rt_sigprocmask. + */ -SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, set, +SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset, old_sigset_t __user *, oset) { - int error; old_sigset_t old_set, new_set; + sigset_t new_blocked; - if (set) { - error = -EFAULT; - if (copy_from_user(&new_set, set, sizeof(*set))) - goto out; + old_set = current->blocked.sig[0]; + + if (nset) { + if (copy_from_user(&new_set, nset, sizeof(*nset))) + return -EFAULT; new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP)); - spin_lock_irq(¤t->sighand->siglock); - old_set = current->blocked.sig[0]; + new_blocked = current->blocked; - error = 0; switch (how) { - default: - error = -EINVAL; - break; case SIG_BLOCK: - sigaddsetmask(¤t->blocked, new_set); + sigaddsetmask(&new_blocked, new_set); break; case SIG_UNBLOCK: - sigdelsetmask(¤t->blocked, new_set); + sigdelsetmask(&new_blocked, new_set); break; case SIG_SETMASK: - current->blocked.sig[0] = new_set; + new_blocked.sig[0] = new_set; break; + default: + return -EINVAL; } - recalc_sigpending(); - spin_unlock_irq(¤t->sighand->siglock); - if (error) - goto out; - if (oset) - goto set_old; - } else if (oset) { - old_set = current->blocked.sig[0]; - set_old: - error = -EFAULT; + set_current_blocked(&new_blocked); + } + + if (oset) { if (copy_to_user(oset, &old_set, sizeof(*oset))) - goto out; + return -EFAULT; } - error = 0; -out: - return error; + + return 0; } #endif /* __ARCH_WANT_SYS_SIGPROCMASK */ #ifdef __ARCH_WANT_SYS_RT_SIGACTION +/** + * sys_rt_sigaction - alter an action taken by a process + * @sig: signal to be sent + * @act: new sigaction + * @oact: used to save the previous sigaction + * @sigsetsize: size of sigset_t type + */ SYSCALL_DEFINE4(rt_sigaction, int, sig, const struct sigaction __user *, act, struct sigaction __user *, oact, @@ -2740,6 +3031,12 @@ SYSCALL_DEFINE0(pause) #endif #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND +/** + * sys_rt_sigsuspend - replace the signal mask for a value with the + * @unewset value until a signal is received + * @unewset: new signal mask value + * @sigsetsize: size of sigset_t type + */ SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize) { sigset_t newset; |