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-rw-r--r--kernel/signal.c137
1 files changed, 120 insertions, 17 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 206551563cce..739c2e40d982 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -344,13 +344,45 @@ static bool task_participate_group_stop(struct task_struct *task)
return false;
}
+#ifdef __HAVE_ARCH_CMPXCHG
+static inline struct sigqueue *get_task_cache(struct task_struct *t)
+{
+ struct sigqueue *q = t->sigqueue_cache;
+
+ if (cmpxchg(&t->sigqueue_cache, q, NULL) != q)
+ return NULL;
+ return q;
+}
+
+static inline int put_task_cache(struct task_struct *t, struct sigqueue *q)
+{
+ if (cmpxchg(&t->sigqueue_cache, NULL, q) == NULL)
+ return 0;
+ return 1;
+}
+
+#else
+
+static inline struct sigqueue *get_task_cache(struct task_struct *t)
+{
+ return NULL;
+}
+
+static inline int put_task_cache(struct task_struct *t, struct sigqueue *q)
+{
+ return 1;
+}
+
+#endif
+
/*
* allocate a new signal queue record
* - this may be called without locks if and only if t == current, otherwise an
* 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)
+__sigqueue_do_alloc(int sig, struct task_struct *t, gfp_t flags,
+ int override_rlimit, int fromslab)
{
struct sigqueue *q = NULL;
struct user_struct *user;
@@ -367,7 +399,10 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimi
if (override_rlimit ||
atomic_read(&user->sigpending) <=
task_rlimit(t, RLIMIT_SIGPENDING)) {
- q = kmem_cache_alloc(sigqueue_cachep, flags);
+ if (!fromslab)
+ q = get_task_cache(t);
+ if (!q)
+ q = kmem_cache_alloc(sigqueue_cachep, flags);
} else {
print_dropped_signal(sig);
}
@@ -384,6 +419,13 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimi
return q;
}
+static struct sigqueue *
+__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags,
+ int override_rlimit)
+{
+ return __sigqueue_do_alloc(sig, t, flags, override_rlimit, 0);
+}
+
static void __sigqueue_free(struct sigqueue *q)
{
if (q->flags & SIGQUEUE_PREALLOC)
@@ -393,6 +435,21 @@ static void __sigqueue_free(struct sigqueue *q)
kmem_cache_free(sigqueue_cachep, q);
}
+static void sigqueue_free_current(struct sigqueue *q)
+{
+ struct user_struct *up;
+
+ if (q->flags & SIGQUEUE_PREALLOC)
+ return;
+
+ up = q->user;
+ if (rt_prio(current->normal_prio) && !put_task_cache(current, q)) {
+ atomic_dec(&up->sigpending);
+ free_uid(up);
+ } else
+ __sigqueue_free(q);
+}
+
void flush_sigqueue(struct sigpending *queue)
{
struct sigqueue *q;
@@ -406,6 +463,21 @@ void flush_sigqueue(struct sigpending *queue)
}
/*
+ * Called from __exit_signal. Flush tsk->pending and
+ * tsk->sigqueue_cache
+ */
+void flush_task_sigqueue(struct task_struct *tsk)
+{
+ struct sigqueue *q;
+
+ flush_sigqueue(&tsk->pending);
+
+ q = get_task_cache(tsk);
+ if (q)
+ kmem_cache_free(sigqueue_cachep, q);
+}
+
+/*
* Flush all pending signals for a task.
*/
void __flush_signals(struct task_struct *t)
@@ -554,7 +626,7 @@ static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
still_pending:
list_del_init(&first->list);
copy_siginfo(info, &first->info);
- __sigqueue_free(first);
+ sigqueue_free_current(first);
} else {
/*
* Ok, it wasn't in the queue. This must be
@@ -600,6 +672,8 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
{
int signr;
+ WARN_ON_ONCE(tsk != current);
+
/* We only dequeue private signals from ourselves, we don't let
* signalfd steal them
*/
@@ -682,6 +756,9 @@ void signal_wake_up(struct task_struct *t, int resume)
set_tsk_thread_flag(t, TIF_SIGPENDING);
+ if (unlikely(t == current))
+ return;
+
/*
* For SIGKILL, we want to wake it up in the stopped/traced/killable
* case. We don't check t->state here because there is a race with it
@@ -1196,8 +1273,8 @@ int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
* We don't want to have recursive SIGSEGV's etc, for example,
* that is why we also clear SIGNAL_UNKILLABLE.
*/
-int
-force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
+static int
+do_force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
unsigned long int flags;
int ret, blocked, ignored;
@@ -1222,6 +1299,39 @@ force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
return ret;
}
+int force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
+{
+/*
+ * On some archs, PREEMPT_RT has to delay sending a signal from a trap
+ * since it can not enable preemption, and the signal code's spin_locks
+ * turn into mutexes. Instead, it must set TIF_NOTIFY_RESUME which will
+ * send the signal on exit of the trap.
+ */
+#ifdef ARCH_RT_DELAYS_SIGNAL_SEND
+ if (in_atomic()) {
+ if (WARN_ON_ONCE(t != current))
+ return 0;
+ if (WARN_ON_ONCE(t->forced_info.si_signo))
+ return 0;
+
+ if (is_si_special(info)) {
+ WARN_ON_ONCE(info != SEND_SIG_PRIV);
+ t->forced_info.si_signo = sig;
+ t->forced_info.si_errno = 0;
+ t->forced_info.si_code = SI_KERNEL;
+ t->forced_info.si_pid = 0;
+ t->forced_info.si_uid = 0;
+ } else {
+ t->forced_info = *info;
+ }
+
+ set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
+ return 0;
+ }
+#endif
+ return do_force_sig_info(sig, info, t);
+}
+
/*
* Nuke all other threads in the group.
*/
@@ -1252,12 +1362,12 @@ struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
struct sighand_struct *sighand;
for (;;) {
- local_irq_save(*flags);
+ local_irq_save_nort(*flags);
rcu_read_lock();
sighand = rcu_dereference(tsk->sighand);
if (unlikely(sighand == NULL)) {
rcu_read_unlock();
- local_irq_restore(*flags);
+ local_irq_restore_nort(*flags);
break;
}
@@ -1268,7 +1378,7 @@ struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
}
spin_unlock(&sighand->siglock);
rcu_read_unlock();
- local_irq_restore(*flags);
+ local_irq_restore_nort(*flags);
}
return sighand;
@@ -1515,7 +1625,8 @@ EXPORT_SYMBOL(kill_pid);
*/
struct sigqueue *sigqueue_alloc(void)
{
- struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
+ /* Preallocated sigqueue objects always from the slabcache ! */
+ struct sigqueue *q = __sigqueue_do_alloc(-1, current, GFP_KERNEL, 0, 1);
if (q)
q->flags |= SIGQUEUE_PREALLOC;
@@ -1857,15 +1968,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
if (gstop_done && ptrace_reparented(current))
do_notify_parent_cldstop(current, false, why);
- /*
- * Don't want to allow preemption here, because
- * sys_ptrace() needs this task to be inactive.
- *
- * XXX: implement read_unlock_no_resched().
- */
- preempt_disable();
read_unlock(&tasklist_lock);
- preempt_enable_no_resched();
schedule();
} else {
/*
generated by cgit v1.2.3 (git 2.0.4) at 2024-11-11 23:27:27 +0000