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-rw-r--r--kernel/signal.c84
1 files changed, 80 insertions, 4 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 8ed7287..ed06b65 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -14,6 +14,7 @@
#include <linux/export.h>
#include <linux/init.h>
#include <linux/sched.h>
+#include <linux/sched/rt.h>
#include <linux/fs.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
@@ -349,13 +350,45 @@ 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;
@@ -372,7 +405,10 @@ __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);
}
@@ -389,6 +425,13 @@ __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)
@@ -398,6 +441,21 @@ 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;
@@ -411,6 +469,21 @@ 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)
@@ -562,7 +635,7 @@ 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
@@ -608,6 +681,8 @@ 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
*/
@@ -1547,7 +1622,8 @@ 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;