[PATCH 1/4] ptrace: temporary revert the recent ptrace/jobctl rework
Oleg Nesterov
oleg at redhat.com
Mon Jun 20 16:07:44 UTC 2011
Temporary revert the following patches to keep utrace/utrace-ptrace working:
40ae717d1e78d982bd469b2013a4cbf4ec1ca434
ptrace: fix signal->wait_chldexit usage in task_clear_group_stop_trapping()
321fb561971ba0f10ce18c0f8a4b9fbfc7cef4b9
ptrace: ptrace_check_attach() should not do s/STOPPED/TRACED/
ee77f075921730b2b465880f9fd4367003bdab39
signal: Turn SIGNAL_STOP_DEQUEUED into GROUP_STOP_DEQUEUED
780006eac2fe7f4d2582da16a096e5a44c4767ff
signal: do_signal_stop: Remove the unneeded task_clear_group_stop_pending()
244056f9dbbc6dc4126a301c745fa3dd67d8af3c
job control: Don't send duplicate job control stop notification while ptraced
ceb6bd67f9b9db765e1c29405f26e8460391badd
job control: Notify the real parent of job control events regardless of ptrace
62bcf9d992ecc19ea4f37ff57ee0b3333e3e843e
job control: Job control stop notifications should always go to the real parent
75b95953a56969a990e6ce154b260be83818fe71
job control: Add @for_ptrace to do_notify_parent_cldstop()
45cb24a1da53beb70f09efccc0373f6a47a9efe0
job control: Allow access to job control events through ptracees
9b84cca2564b9a5b2d064fb44d2a55a5b44473a0
job control: Fix ptracer wait(2) hang and explain notask_error clearing
408a37de6c95832a4880a88a742f89f0cc554d06
job control: Don't set group_stop exit_code if re-entering job control stop
0e9f0a4abfd80f8adca624538d479d95159b16d8
ptrace: Always put ptracee into appropriate execution state
e3bd058f62896ec7a2c605ed62a0a811e9147947
ptrace: Collapse ptrace_untrace() into __ptrace_unlink()
d79fdd6d96f46fabb779d86332e3677c6f5c2a4f
ptrace: Clean transitions between TASK_STOPPED and TRACED
5224fa3660ad3881d2f2ad726d22614117963f10
ptrace: Make do_signal_stop() use ptrace_stop() if the task is being ptraced
0ae8ce1c8c5b9007ce6bfc83ec2aa0dfce5bbed3
ptrace: Participate in group stop from ptrace_stop() iff the task is trapping for group stop
39efa3ef3a376a4e53de2f82fc91182459d34200
signal: Use GROUP_STOP_PENDING to stop once for a single group stop
e5c1902e9260a0075ea52cb5ef627a8d9aaede89
signal: Fix premature completion of group stop when interfered by ptrace
fe1bc6a0954611b806f9e158eb0817cf8ba21660
ptrace: Add @why to ptrace_stop()
edf2ed153bcae52de70db00a98b0e81a5668e563
ptrace: Kill tracehook_notify_jctl()
This obviously reverts some user-visible fixes, but the fixed problems
are very old and minor, they were never reported. In the long term we
need another solution.
Signed-off-by: Oleg Nesterov <oleg at redhat.com>
---
fs/exec.c | 1 -
include/linux/sched.h | 17 +--
include/linux/tracehook.h | 27 ++++
kernel/exit.c | 77 ++---------
kernel/ptrace.c | 116 +++++-----------
kernel/signal.c | 339 +++++++++------------------------------------
6 files changed, 148 insertions(+), 429 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index 6075a1e..82b5379 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1769,7 +1769,6 @@ static int zap_process(struct task_struct *start, int exit_code)
t = start;
do {
- task_clear_group_stop_pending(t);
if (t != current && t->mm) {
sigaddset(&t->pending.signal, SIGKILL);
signal_wake_up(t, 1);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a837b20..6c42e24 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -663,8 +663,9 @@ struct signal_struct {
* Bits in flags field of signal_struct.
*/
#define SIGNAL_STOP_STOPPED 0x00000001 /* job control stop in effect */
-#define SIGNAL_STOP_CONTINUED 0x00000002 /* SIGCONT since WCONTINUED reap */
-#define SIGNAL_GROUP_EXIT 0x00000004 /* group exit in progress */
+#define SIGNAL_STOP_DEQUEUED 0x00000002 /* stop signal dequeued */
+#define SIGNAL_STOP_CONTINUED 0x00000004 /* SIGCONT since WCONTINUED reap */
+#define SIGNAL_GROUP_EXIT 0x00000008 /* group exit in progress */
/*
* Pending notifications to parent.
*/
@@ -1283,7 +1284,6 @@ struct task_struct {
int exit_state;
int exit_code, exit_signal;
int pdeath_signal; /* The signal sent when the parent dies */
- unsigned int group_stop; /* GROUP_STOP_*, siglock protected */
/* ??? */
unsigned int personality;
unsigned did_exec:1;
@@ -1803,17 +1803,6 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
#define tsk_used_math(p) ((p)->flags & PF_USED_MATH)
#define used_math() tsk_used_math(current)
-/*
- * task->group_stop flags
- */
-#define GROUP_STOP_SIGMASK 0xffff /* signr of the last group stop */
-#define GROUP_STOP_PENDING (1 << 16) /* task should stop for group stop */
-#define GROUP_STOP_CONSUME (1 << 17) /* consume group stop count */
-#define GROUP_STOP_TRAPPING (1 << 18) /* switching from STOPPED to TRACED */
-#define GROUP_STOP_DEQUEUED (1 << 19) /* stop signal dequeued */
-
-extern void task_clear_group_stop_pending(struct task_struct *task);
-
#ifdef CONFIG_PREEMPT_RCU
#define RCU_READ_UNLOCK_BLOCKED (1 << 0) /* blocked while in RCU read-side. */
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index e95f523..ebcfa4e 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -469,6 +469,33 @@ static inline int tracehook_get_signal(struct task_struct *task,
}
/**
+ * tracehook_notify_jctl - report about job control stop/continue
+ * @notify: zero, %CLD_STOPPED or %CLD_CONTINUED
+ * @why: %CLD_STOPPED or %CLD_CONTINUED
+ *
+ * This is called when we might call do_notify_parent_cldstop().
+ *
+ * @notify is zero if we would not ordinarily send a %SIGCHLD,
+ * or is the %CLD_STOPPED or %CLD_CONTINUED .si_code for %SIGCHLD.
+ *
+ * @why is %CLD_STOPPED when about to stop for job control;
+ * we are already in %TASK_STOPPED state, about to call schedule().
+ * It might also be that we have just exited (check %PF_EXITING),
+ * but need to report that a group-wide stop is complete.
+ *
+ * @why is %CLD_CONTINUED when waking up after job control stop and
+ * ready to make a delayed @notify report.
+ *
+ * Return the %CLD_* value for %SIGCHLD, or zero to generate no signal.
+ *
+ * Called with the siglock held.
+ */
+static inline int tracehook_notify_jctl(int notify, int why)
+{
+ return notify ?: (current->ptrace & PT_PTRACED) ? why : 0;
+}
+
+/**
* tracehook_finish_jctl - report about return from job control stop
*
* This is called by do_signal_stop() after wakeup.
diff --git a/kernel/exit.c b/kernel/exit.c
index f2b321b..a86fca4 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1556,80 +1556,31 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace,
if (p->exit_state == EXIT_DEAD)
return 0;
- /* slay zombie? */
- if (p->exit_state == EXIT_ZOMBIE) {
+ if (likely(!ptrace) && unlikely(task_ptrace(p))) {
/*
- * A zombie ptracee is only visible to its ptracer.
- * Notification and reaping will be cascaded to the real
- * parent when the ptracer detaches.
- */
- if (likely(!ptrace) && unlikely(task_ptrace(p))) {
- /* it will become visible, clear notask_error */
- wo->notask_error = 0;
- return 0;
- }
-
- /* we don't reap group leaders with subthreads */
- if (!delay_group_leader(p))
- return wait_task_zombie(wo, p);
-
- /*
- * Allow access to stopped/continued state via zombie by
- * falling through. Clearing of notask_error is complex.
- *
- * When !@ptrace:
- *
- * If WEXITED is set, notask_error should naturally be
- * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
- * so, if there are live subthreads, there are events to
- * wait for. If all subthreads are dead, it's still safe
- * to clear - this function will be called again in finite
- * amount time once all the subthreads are released and
- * will then return without clearing.
- *
- * When @ptrace:
- *
- * Stopped state is per-task and thus can't change once the
- * target task dies. Only continued and exited can happen.
- * Clear notask_error if WCONTINUED | WEXITED.
- */
- if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
- wo->notask_error = 0;
- } else {
- /*
- * If @p is ptraced by a task in its real parent's group,
- * hide group stop/continued state when looking at @p as
- * the real parent; otherwise, a single stop can be
- * reported twice as group and ptrace stops.
- *
- * If a ptracer wants to distinguish the two events for its
- * own children, it should create a separate process which
- * takes the role of real parent.
- */
- if (likely(!ptrace) && task_ptrace(p) &&
- same_thread_group(p->parent, p->real_parent))
- return 0;
-
- /*
- * @p is alive and it's gonna stop, continue or exit, so
- * there always is something to wait for.
+ * This child is hidden by ptrace.
+ * We aren't allowed to see it now, but eventually we will.
*/
wo->notask_error = 0;
+ return 0;
}
/*
- * Wait for stopped. Depending on @ptrace, different stopped state
- * is used and the two don't interact with each other.
+ * We don't reap group leaders with subthreads.
*/
+ if (p->exit_state == EXIT_ZOMBIE && !delay_group_leader(p))
+ return wait_task_zombie(wo, p);
+
+ /*
+ * It's stopped or running now, so it might
+ * later continue, exit, or stop again.
+ */
+ wo->notask_error = 0;
+
ret = wait_task_stopped(wo, ptrace, p);
if (ret)
return ret;
- /*
- * Wait for continued. There's only one continued state and the
- * ptracer can consume it which can confuse the real parent. Don't
- * use WCONTINUED from ptracer. You don't need or want it.
- */
return wait_task_continued(wo, p);
}
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 2df1157..5cb3003 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -38,33 +38,35 @@ void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
child->parent = new_parent;
}
-/**
- * __ptrace_unlink - unlink ptracee and restore its execution state
- * @child: ptracee to be unlinked
- *
- * Remove @child from the ptrace list, move it back to the original parent,
- * and restore the execution state so that it conforms to the group stop
- * state.
- *
- * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
- * exiting. For PTRACE_DETACH, unless the ptracee has been killed between
- * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
- * If the ptracer is exiting, the ptracee can be in any state.
- *
- * After detach, the ptracee should be in a state which conforms to the
- * group stop. If the group is stopped or in the process of stopping, the
- * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
- * up from TASK_TRACED.
- *
- * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
- * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
- * to but in the opposite direction of what happens while attaching to a
- * stopped task. However, in this direction, the intermediate RUNNING
- * state is not hidden even from the current ptracer and if it immediately
- * re-attaches and performs a WNOHANG wait(2), it may fail.
+/*
+ * Turn a tracing stop into a normal stop now, since with no tracer there
+ * would be no way to wake it up with SIGCONT or SIGKILL. If there was a
+ * signal sent that would resume the child, but didn't because it was in
+ * TASK_TRACED, resume it now.
+ * Requires that irqs be disabled.
+ */
+static void ptrace_untrace(struct task_struct *child)
+{
+ spin_lock(&child->sighand->siglock);
+ if (task_is_traced(child)) {
+ /*
+ * If the group stop is completed or in progress,
+ * this thread was already counted as stopped.
+ */
+ if (child->signal->flags & SIGNAL_STOP_STOPPED ||
+ child->signal->group_stop_count)
+ __set_task_state(child, TASK_STOPPED);
+ else
+ signal_wake_up(child, 1);
+ }
+ spin_unlock(&child->sighand->siglock);
+}
+
+/*
+ * unptrace a task: move it back to its original parent and
+ * remove it from the ptrace list.
*
- * CONTEXT:
- * write_lock_irq(tasklist_lock)
+ * Must be called with the tasklist lock write-held.
*/
void __ptrace_unlink(struct task_struct *child)
{
@@ -74,27 +76,8 @@ void __ptrace_unlink(struct task_struct *child)
child->parent = child->real_parent;
list_del_init(&child->ptrace_entry);
- spin_lock(&child->sighand->siglock);
-
- /*
- * Reinstate GROUP_STOP_PENDING if group stop is in effect and
- * @child isn't dead.
- */
- if (!(child->flags & PF_EXITING) &&
- (child->signal->flags & SIGNAL_STOP_STOPPED ||
- child->signal->group_stop_count))
- child->group_stop |= GROUP_STOP_PENDING;
-
- /*
- * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
- * @child in the butt. Note that @resume should be used iff @child
- * is in TASK_TRACED; otherwise, we might unduly disrupt
- * TASK_KILLABLE sleeps.
- */
- if (child->group_stop & GROUP_STOP_PENDING || task_is_traced(child))
- signal_wake_up(child, task_is_traced(child));
-
- spin_unlock(&child->sighand->siglock);
+ if (task_is_traced(child))
+ ptrace_untrace(child);
}
/*
@@ -113,14 +96,16 @@ int ptrace_check_attach(struct task_struct *child, int kill)
*/
read_lock(&tasklist_lock);
if ((child->ptrace & PT_PTRACED) && child->parent == current) {
+ ret = 0;
/*
* child->sighand can't be NULL, release_task()
* does ptrace_unlink() before __exit_signal().
*/
spin_lock_irq(&child->sighand->siglock);
- WARN_ON_ONCE(task_is_stopped(child));
- if (task_is_traced(child) || kill)
- ret = 0;
+ if (task_is_stopped(child))
+ child->state = TASK_TRACED;
+ else if (!task_is_traced(child) && !kill)
+ ret = -ESRCH;
spin_unlock_irq(&child->sighand->siglock);
}
read_unlock(&tasklist_lock);
@@ -184,7 +169,6 @@ bool ptrace_may_access(struct task_struct *task, unsigned int mode)
static int ptrace_attach(struct task_struct *task)
{
- bool wait_trap = false;
int retval;
audit_ptrace(task);
@@ -224,42 +208,12 @@ static int ptrace_attach(struct task_struct *task)
__ptrace_link(task, current);
send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
- spin_lock(&task->sighand->siglock);
-
- /*
- * If the task is already STOPPED, set GROUP_STOP_PENDING and
- * TRAPPING, and kick it so that it transits to TRACED. TRAPPING
- * will be cleared if the child completes the transition or any
- * event which clears the group stop states happens. We'll wait
- * for the transition to complete before returning from this
- * function.
- *
- * This hides STOPPED -> RUNNING -> TRACED transition from the
- * attaching thread but a different thread in the same group can
- * still observe the transient RUNNING state. IOW, if another
- * thread's WNOHANG wait(2) on the stopped tracee races against
- * ATTACH, the wait(2) may fail due to the transient RUNNING.
- *
- * The following task_is_stopped() test is safe as both transitions
- * in and out of STOPPED are protected by siglock.
- */
- if (task_is_stopped(task)) {
- task->group_stop |= GROUP_STOP_PENDING | GROUP_STOP_TRAPPING;
- signal_wake_up(task, 1);
- wait_trap = true;
- }
-
- spin_unlock(&task->sighand->siglock);
-
retval = 0;
unlock_tasklist:
write_unlock_irq(&tasklist_lock);
unlock_creds:
mutex_unlock(&task->signal->cred_guard_mutex);
out:
- if (wait_trap)
- wait_event(current->signal->wait_chldexit,
- !(task->group_stop & GROUP_STOP_TRAPPING));
return retval;
}
diff --git a/kernel/signal.c b/kernel/signal.c
index ff76786..23a31b6 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->group_stop & GROUP_STOP_PENDING) ||
+ if (t->signal->group_stop_count > 0 ||
PENDING(&t->pending, &t->blocked) ||
PENDING(&t->signal->shared_pending, &t->blocked)) {
set_tsk_thread_flag(t, TIF_SIGPENDING);
@@ -223,83 +223,6 @@ 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
@@ -604,7 +527,7 @@ 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.
*/
- current->group_stop |= GROUP_STOP_DEQUEUED;
+ tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
}
if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
/*
@@ -809,7 +732,6 @@ static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
t = p;
do {
- task_clear_group_stop_pending(t);
rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
wake_up_state(t, __TASK_STOPPED);
} while_each_thread(p, t);
@@ -837,6 +759,13 @@ 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;
}
}
@@ -925,7 +854,6 @@ 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);
@@ -1160,7 +1088,6 @@ 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 */
@@ -1588,30 +1515,16 @@ int do_notify_parent(struct task_struct *tsk, int sig)
return ret;
}
-/**
- * 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)
+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 (for_ptracer) {
+ if (task_ptrace(tsk))
parent = tsk->parent;
- } else {
+ else {
tsk = tsk->group_leader;
parent = tsk->real_parent;
}
@@ -1687,15 +1600,6 @@ 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.
@@ -1706,12 +1610,10 @@ static bool real_parent_is_ptracer(struct task_struct *child)
* 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 why, int clear_code, siginfo_t *info)
+static void ptrace_stop(int exit_code, 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
@@ -1732,49 +1634,21 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
}
/*
- * 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 there is a group stop in progress,
+ * we must participate in the bookkeeping.
*/
- if (why == CLD_STOPPED && (current->group_stop & GROUP_STOP_PENDING))
- gstop_done = task_participate_group_stop(current);
+ if (current->signal->group_stop_count > 0)
+ --current->signal->group_stop_count;
current->last_siginfo = info;
current->exit_code = exit_code;
- /*
- * 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);
-
+ /* Let the debugger run. */
+ __set_current_state(TASK_TRACED);
spin_unlock_irq(¤t->sighand->siglock);
read_lock(&tasklist_lock);
if (may_ptrace_stop()) {
- /*
- * 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);
-
+ do_notify_parent_cldstop(current, CLD_TRAPPED);
/*
* Don't want to allow preemption here, because
* sys_ptrace() needs this task to be inactive.
@@ -1789,16 +1663,7 @@ static void ptrace_stop(int exit_code, int why, 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;
@@ -1842,7 +1707,7 @@ void ptrace_notify(int exit_code)
/* Let the debugger run. */
spin_lock_irq(¤t->sighand->siglock);
- ptrace_stop(exit_code, CLD_TRAPPED, 1, &info);
+ ptrace_stop(exit_code, 1, &info);
spin_unlock_irq(¤t->sighand->siglock);
}
@@ -1855,115 +1720,64 @@ void ptrace_notify(int exit_code)
static int do_signal_stop(int signr)
{
struct signal_struct *sig = current->signal;
+ int notify;
- if (!(current->group_stop & GROUP_STOP_PENDING)) {
- unsigned int gstop = GROUP_STOP_PENDING | GROUP_STOP_CONSUME;
+ if (!sig->group_stop_count) {
struct task_struct *t;
- /* 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) ||
+ if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
unlikely(signal_group_exit(sig)))
return 0;
/*
- * 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.
+ * There is no group stop already in progress.
+ * We must initiate one now.
*/
- if (!(sig->flags & SIGNAL_STOP_STOPPED))
- sig->group_exit_code = signr;
- else
- WARN_ON_ONCE(!task_ptrace(current));
+ sig->group_exit_code = signr;
- 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)) {
- t->group_stop &= ~GROUP_STOP_SIGMASK;
+ 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->flags & PF_EXITING) && !task_is_stopped(t)) {
- t->group_stop |= signr | gstop;
+ if (!(t->flags & PF_EXITING) &&
+ !task_is_stopped_or_traced(t)) {
sig->group_stop_count++;
signal_wake_up(t, 0);
}
- }
}
-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;
- }
-
/*
- * 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 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 (current->group_stop & GROUP_STOP_PENDING) {
- WARN_ON_ONCE(!(current->group_stop & GROUP_STOP_SIGMASK));
- goto retry;
+ if (sig->group_stop_count) {
+ if (!--sig->group_stop_count)
+ sig->flags = SIGNAL_STOP_STOPPED;
+ current->exit_code = sig->group_exit_code;
+ __set_current_state(TASK_STOPPED);
}
+ spin_unlock_irq(¤t->sighand->siglock);
- /* PTRACE_ATTACH might have raced with task killing, clear trapping */
- task_clear_group_stop_trapping(current);
+ if (notify) {
+ read_lock(&tasklist_lock);
+ do_notify_parent_cldstop(current, notify);
+ read_unlock(&tasklist_lock);
+ }
- spin_unlock_irq(¤t->sighand->siglock);
+ /* Now we don't run again until woken by SIGCONT or SIGKILL */
+ schedule();
tracehook_finish_jctl();
+ current->exit_code = 0;
return 1;
}
@@ -1977,7 +1791,7 @@ static int ptrace_signal(int signr, siginfo_t *info,
ptrace_signal_deliver(regs, cookie);
/* Let the debugger run. */
- ptrace_stop(signr, CLD_TRAPPED, 0, info);
+ ptrace_stop(signr, 0, info);
/* We're back. Did the debugger cancel the sig? */
signr = current->exit_code;
@@ -2032,7 +1846,6 @@ relock:
* the CLD_ si_code into SIGNAL_CLD_MASK bits.
*/
if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
- struct task_struct *leader;
int why;
if (signal->flags & SIGNAL_CLD_CONTINUED)
@@ -2042,26 +1855,14 @@ relock:
signal->flags &= ~SIGNAL_CLD_MASK;
+ why = tracehook_notify_jctl(why, CLD_CONTINUED);
spin_unlock_irq(&sighand->siglock);
- /*
- * 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);
-
+ if (why) {
+ read_lock(&tasklist_lock);
+ do_notify_parent_cldstop(current->group_leader, why);
+ read_unlock(&tasklist_lock);
+ }
goto relock;
}
@@ -2078,8 +1879,8 @@ relock:
if (unlikely(signr != 0))
ka = return_ka;
else {
- if (unlikely(current->group_stop &
- GROUP_STOP_PENDING) && do_signal_stop(0))
+ if (unlikely(signal->group_stop_count > 0) &&
+ do_signal_stop(0))
goto relock;
signr = dequeue_signal(current, ¤t->blocked,
@@ -2253,19 +2054,17 @@ void exit_signals(struct task_struct *tsk)
signotset(&unblocked);
retarget_shared_pending(tsk, &unblocked);
- if (unlikely(tsk->group_stop & GROUP_STOP_PENDING) &&
- task_participate_group_stop(tsk))
- group_stop = CLD_STOPPED;
+ 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);
+ }
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, false, group_stop);
+ do_notify_parent_cldstop(tsk, group_stop);
read_unlock(&tasklist_lock);
}
}
--
1.5.5.1
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