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Subject[PATCH 04/19] job control: introduce JOBCTL_PENDING_MASK and task_clear_jobctl_pending()
Date
This patch introduces JOBCTL_PENDING_MASK and replaces
task_clear_jobctl_stop_pending() with task_clear_jobctl_pending()
which takes an extra @mask argument.

JOBCTL_PENDING_MASK is currently equal to JOBCTL_STOP_PENDING but
future patches will add more bits. recalc_sigpending_tsk() is updated
to use JOBCTL_PENDING_MASK instead.

task_clear_jobctl_pending() takes @mask which in subset of
JOBCTL_PENDING_MASK and clears the relevant jobctl bits. If
JOBCTL_STOP_PENDING is set, other STOP bits are cleared together. All
task_clear_jobctl_stop_pending() users are updated to call
task_clear_jobctl_pending() with JOBCTL_STOP_PENDING which is
functionally identical to task_clear_jobctl_stop_pending().

This patch doesn't cause any functional change.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
fs/exec.c | 2 +-
include/linux/sched.h | 5 ++++-
kernel/signal.c | 27 +++++++++++++++++----------
3 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 223e3b2..5b83ba9 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1735,7 +1735,7 @@ static int zap_process(struct task_struct *start, int exit_code)

t = start;
do {
- task_clear_jobctl_stop_pending(t);
+ task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
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 01178e6..e0ce64c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1801,7 +1801,10 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
#define JOBCTL_STOP_CONSUME (1 << 18) /* consume group stop count */
#define JOBCTL_TRAPPING (1 << 21) /* switching to TRACED */

-extern void task_clear_jobctl_stop_pending(struct task_struct *task);
+#define JOBCTL_PENDING_MASK JOBCTL_STOP_PENDING
+
+extern void task_clear_jobctl_pending(struct task_struct *task,
+ unsigned int mask);

#ifdef CONFIG_PREEMPT_RCU

diff --git a/kernel/signal.c b/kernel/signal.c
index eef44fd..8033d86 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->jobctl & JOBCTL_STOP_PENDING) ||
+ if ((t->jobctl & JOBCTL_PENDING_MASK) ||
PENDING(&t->pending, &t->blocked) ||
PENDING(&t->signal->shared_pending, &t->blocked)) {
set_tsk_thread_flag(t, TIF_SIGPENDING);
@@ -245,18 +245,25 @@ static void task_clear_jobctl_trapping(struct task_struct *task)
}

/**
- * task_clear_jobctl_stop_pending - clear pending group stop
+ * task_clear_jobctl_pending - clear jobctl pending bits
* @task: target task
+ * @mask: pending bits to clear
*
- * Clear group stop states for @task.
+ * Clear @mask from @task->jobctl. @mask must be subset of
+ * %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
+ * STOP bits are cleared together.
*
* CONTEXT:
* Must be called with @task->sighand->siglock held.
*/
-void task_clear_jobctl_stop_pending(struct task_struct *task)
+void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
{
- task->jobctl &= ~(JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME |
- JOBCTL_STOP_DEQUEUED);
+ BUG_ON(mask & ~JOBCTL_PENDING_MASK);
+
+ if (mask & JOBCTL_STOP_PENDING)
+ mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
+
+ task->jobctl &= ~mask;
}

/**
@@ -282,7 +289,7 @@ static bool task_participate_group_stop(struct task_struct *task)

WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));

- task_clear_jobctl_stop_pending(task);
+ task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);

if (!consume)
return false;
@@ -810,7 +817,7 @@ 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_jobctl_stop_pending(t);
+ task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
wake_up_state(t, __TASK_STOPPED);
} while_each_thread(p, t);
@@ -926,7 +933,7 @@ static void complete_signal(int sig, struct task_struct *p, int group)
signal->group_stop_count = 0;
t = p;
do {
- task_clear_jobctl_stop_pending(t);
+ task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
sigaddset(&t->pending.signal, SIGKILL);
signal_wake_up(t, 1);
} while_each_thread(p, t);
@@ -1161,7 +1168,7 @@ int zap_other_threads(struct task_struct *p)
p->signal->group_stop_count = 0;

while_each_thread(p, t) {
- task_clear_jobctl_stop_pending(t);
+ task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
count++;

/* Don't bother with already dead threads */
--
1.7.1


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