sched/headers: Move task_struct::signal and task_struct::sighand types and accessors into <linux/sched/signal.h>

task_struct::signal and task_struct::sighand are pointers, which would normally make it
straightforward to not define those types in sched.h.

That is not so, because the types are accompanied by a myriad of APIs (macros and inline
functions) that dereference them.

Split the types and the APIs out of sched.h and move them into a new header, <linux/sched/signal.h>.

With this change sched.h does not know about 'struct signal' and 'struct sighand' anymore,
trying to put accessors into sched.h as a test fails the following way:

  ./include/linux/sched.h: In function ‘test_signal_types’:
  ./include/linux/sched.h:2461:18: error: dereferencing pointer to incomplete type ‘struct signal_struct’
                    ^

This reduces the size and complexity of sched.h significantly.

Update all headers and .c code that relied on getting the signal handling
functionality from <linux/sched.h> to include <linux/sched/signal.h>.

The list of affected files in the preparatory patch was partly generated by
grepping for the APIs, and partly by doing coverage build testing, both
all[yes|mod|def|no]config builds on 64-bit and 32-bit x86, and an array of
cross-architecture builds.

Nevertheless some (trivial) build breakage is still expected related to rare
Kconfig combinations and in-flight patches to various kernel code, but most
of it should be handled by this patch.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 3 insertions, 496 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 7934cd0acbc7..c1586104d4c0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -71,6 +71,9 @@ struct blk_plug;
 struct filename;
 struct nameidata;
 
+struct signal_struct;
+struct sighand_struct;
+
 extern unsigned long total_forks;
 extern int nr_threads;
 DECLARE_PER_CPU(unsigned long, process_counts);
@@ -361,13 +364,6 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 static inline void arch_pick_mmap_layout(struct mm_struct *mm) {}
 #endif
 
-struct sighand_struct {
-        atomic_t                count;
-        struct k_sigaction      action[_NSIG];
-        spinlock_t              siglock;
-        wait_queue_head_t       signalfd_wqh;
-};
-
 struct pacct_struct {
         int                     ac_flag;
         long                    ac_exitcode;
@@ -486,195 +482,6 @@ struct thread_group_cputimer {
 struct autogroup;
 
 /*
- * NOTE! "signal_struct" does not have its own
- * locking, because a shared signal_struct always
- * implies a shared sighand_struct, so locking
- * sighand_struct is always a proper superset of
- * the locking of signal_struct.
- */
-struct signal_struct {
-        atomic_t                sigcnt;
-        atomic_t                live;
-        int                     nr_threads;
-        struct list_head        thread_head;
-
-        wait_queue_head_t       wait_chldexit;  /* for wait4() */
-
-        /* current thread group signal load-balancing target: */
-        struct task_struct      *curr_target;
-
-        /* shared signal handling: */
-        struct sigpending       shared_pending;
-
-        /* thread group exit support */
-        int                     group_exit_code;
-        /* overloaded:
-         * - notify group_exit_task when ->count is equal to notify_count
-         * - everyone except group_exit_task is stopped during signal delivery
-         *   of fatal signals, group_exit_task processes the signal.
-         */
-        int                     notify_count;
-        struct task_struct      *group_exit_task;
-
-        /* thread group stop support, overloads group_exit_code too */
-        int                     group_stop_count;
-        unsigned int            flags; /* see SIGNAL_* flags below */
-
-        /*
-         * PR_SET_CHILD_SUBREAPER marks a process, like a service
-         * manager, to re-parent orphan (double-forking) child processes
-         * to this process instead of 'init'. The service manager is
-         * able to receive SIGCHLD signals and is able to investigate
-         * the process until it calls wait(). All children of this
-         * process will inherit a flag if they should look for a
-         * child_subreaper process at exit.
-         */
-        unsigned int            is_child_subreaper:1;
-        unsigned int            has_child_subreaper:1;
-
-#ifdef CONFIG_POSIX_TIMERS
-
-        /* POSIX.1b Interval Timers */
-        int                     posix_timer_id;
-        struct list_head        posix_timers;
-
-        /* ITIMER_REAL timer for the process */
-        struct hrtimer real_timer;
-        ktime_t it_real_incr;
-
-        /*
-         * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
-         * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
-         * values are defined to 0 and 1 respectively
-         */
-        struct cpu_itimer it[2];
-
-        /*
-         * Thread group totals for process CPU timers.
-         * See thread_group_cputimer(), et al, for details.
-         */
-        struct thread_group_cputimer cputimer;
-
-        /* Earliest-expiration cache. */
-        struct task_cputime cputime_expires;
-
-        struct list_head cpu_timers[3];
-
-#endif
-
-        struct pid *leader_pid;
-
-#ifdef CONFIG_NO_HZ_FULL
-        atomic_t tick_dep_mask;
-#endif
-
-        struct pid *tty_old_pgrp;
-
-        /* boolean value for session group leader */
-        int leader;
-
-        struct tty_struct *tty; /* NULL if no tty */
-
-#ifdef CONFIG_SCHED_AUTOGROUP
-        struct autogroup *autogroup;
-#endif
-        /*
-         * Cumulative resource counters for dead threads in the group,
-         * and for reaped dead child processes forked by this group.
-         * Live threads maintain their own counters and add to these
-         * in __exit_signal, except for the group leader.
-         */
-        seqlock_t stats_lock;
-        u64 utime, stime, cutime, cstime;
-        u64 gtime;
-        u64 cgtime;
-        struct prev_cputime prev_cputime;
-        unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
-        unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
-        unsigned long inblock, oublock, cinblock, coublock;
-        unsigned long maxrss, cmaxrss;
-        struct task_io_accounting ioac;
-
-        /*
-         * Cumulative ns of schedule CPU time fo dead threads in the
-         * group, not including a zombie group leader, (This only differs
-         * from jiffies_to_ns(utime + stime) if sched_clock uses something
-         * other than jiffies.)
-         */
-        unsigned long long sum_sched_runtime;
-
-        /*
-         * We don't bother to synchronize most readers of this at all,
-         * because there is no reader checking a limit that actually needs
-         * to get both rlim_cur and rlim_max atomically, and either one
-         * alone is a single word that can safely be read normally.
-         * getrlimit/setrlimit use task_lock(current->group_leader) to
-         * protect this instead of the siglock, because they really
-         * have no need to disable irqs.
-         */
-        struct rlimit rlim[RLIM_NLIMITS];
-
-#ifdef CONFIG_BSD_PROCESS_ACCT
-        struct pacct_struct pacct;      /* per-process accounting information */
-#endif
-#ifdef CONFIG_TASKSTATS
-        struct taskstats *stats;
-#endif
-#ifdef CONFIG_AUDIT
-        unsigned audit_tty;
-        struct tty_audit_buf *tty_audit_buf;
-#endif
-
-        /*
-         * Thread is the potential origin of an oom condition; kill first on
-         * oom
-         */
-        bool oom_flag_origin;
-        short oom_score_adj;            /* OOM kill score adjustment */
-        short oom_score_adj_min;        /* OOM kill score adjustment min value.
-                                         * Only settable by CAP_SYS_RESOURCE. */
-        struct mm_struct *oom_mm;       /* recorded mm when the thread group got
-                                         * killed by the oom killer */
-
-        struct mutex cred_guard_mutex;  /* guard against foreign influences on
-                                         * credential calculations
-                                         * (notably. ptrace) */
-};
-
-/*
- * 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_GROUP_COREDUMP   0x00000008 /* coredump in progress */
-/*
- * Pending notifications to parent.
- */
-#define SIGNAL_CLD_STOPPED      0x00000010
-#define SIGNAL_CLD_CONTINUED    0x00000020
-#define SIGNAL_CLD_MASK         (SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
-
-#define SIGNAL_UNKILLABLE       0x00000040 /* for init: ignore fatal signals */
-
-#define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
-                          SIGNAL_STOP_CONTINUED)
-
-static inline void signal_set_stop_flags(struct signal_struct *sig,
-                                         unsigned int flags)
-{
-        WARN_ON(sig->flags & (SIGNAL_GROUP_EXIT|SIGNAL_GROUP_COREDUMP));
-        sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
-}
-
-/* If true, all threads except ->group_exit_task have pending SIGKILL */
-static inline int signal_group_exit(const struct signal_struct *sig)
-{
-        return  (sig->flags & SIGNAL_GROUP_EXIT) ||
-                (sig->group_exit_task != NULL);
-}
-
-/*
  * Some day this will be a full-fledged user tracking system..
  */
 struct user_struct {
@@ -2126,190 +1933,8 @@ extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
 extern void sched_dead(struct task_struct *p);
 
 extern void proc_caches_init(void);
-extern void flush_signals(struct task_struct *);
-extern void ignore_signals(struct task_struct *);
-extern void flush_signal_handlers(struct task_struct *, int force_default);
-extern int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info);
-
-static inline int kernel_dequeue_signal(siginfo_t *info)
-{
-        struct task_struct *tsk = current;
-        siginfo_t __info;
-        int ret;
-
-        spin_lock_irq(&tsk->sighand->siglock);
-        ret = dequeue_signal(tsk, &tsk->blocked, info ?: &__info);
-        spin_unlock_irq(&tsk->sighand->siglock);
-
-        return ret;
-}
-
-static inline void kernel_signal_stop(void)
-{
-        spin_lock_irq(&current->sighand->siglock);
-        if (current->jobctl & JOBCTL_STOP_DEQUEUED)
-                __set_current_state(TASK_STOPPED);
-        spin_unlock_irq(&current->sighand->siglock);
-
-        schedule();
-}
 
 extern void release_task(struct task_struct * p);
-extern int send_sig_info(int, struct siginfo *, struct task_struct *);
-extern int force_sigsegv(int, struct task_struct *);
-extern int force_sig_info(int, struct siginfo *, struct task_struct *);
-extern int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp);
-extern int kill_pid_info(int sig, struct siginfo *info, struct pid *pid);
-extern int kill_pid_info_as_cred(int, struct siginfo *, struct pid *,
-                                const struct cred *, u32);
-extern int kill_pgrp(struct pid *pid, int sig, int priv);
-extern int kill_pid(struct pid *pid, int sig, int priv);
-extern int kill_proc_info(int, struct siginfo *, pid_t);
-extern __must_check bool do_notify_parent(struct task_struct *, int);
-extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
-extern void force_sig(int, struct task_struct *);
-extern int send_sig(int, struct task_struct *, int);
-extern int zap_other_threads(struct task_struct *p);
-extern struct sigqueue *sigqueue_alloc(void);
-extern void sigqueue_free(struct sigqueue *);
-extern int send_sigqueue(struct sigqueue *,  struct task_struct *, int group);
-extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
-
-#ifdef TIF_RESTORE_SIGMASK
-/*
- * Legacy restore_sigmask accessors.  These are inefficient on
- * SMP architectures because they require atomic operations.
- */
-
-/**
- * set_restore_sigmask() - make sure saved_sigmask processing gets done
- *
- * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
- * will run before returning to user mode, to process the flag.  For
- * all callers, TIF_SIGPENDING is already set or it's no harm to set
- * it.  TIF_RESTORE_SIGMASK need not be in the set of bits that the
- * arch code will notice on return to user mode, in case those bits
- * are scarce.  We set TIF_SIGPENDING here to ensure that the arch
- * signal code always gets run when TIF_RESTORE_SIGMASK is set.
- */
-static inline void set_restore_sigmask(void)
-{
-        set_thread_flag(TIF_RESTORE_SIGMASK);
-        WARN_ON(!test_thread_flag(TIF_SIGPENDING));
-}
-static inline void clear_restore_sigmask(void)
-{
-        clear_thread_flag(TIF_RESTORE_SIGMASK);
-}
-static inline bool test_restore_sigmask(void)
-{
-        return test_thread_flag(TIF_RESTORE_SIGMASK);
-}
-static inline bool test_and_clear_restore_sigmask(void)
-{
-        return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
-}
-
-#else   /* TIF_RESTORE_SIGMASK */
-
-/* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
-static inline void set_restore_sigmask(void)
-{
-        current->restore_sigmask = true;
-        WARN_ON(!test_thread_flag(TIF_SIGPENDING));
-}
-static inline void clear_restore_sigmask(void)
-{
-        current->restore_sigmask = false;
-}
-static inline bool test_restore_sigmask(void)
-{
-        return current->restore_sigmask;
-}
-static inline bool test_and_clear_restore_sigmask(void)
-{
-        if (!current->restore_sigmask)
-                return false;
-        current->restore_sigmask = false;
-        return true;
-}
-#endif
-
-static inline void restore_saved_sigmask(void)
-{
-        if (test_and_clear_restore_sigmask())
-                __set_current_blocked(&current->saved_sigmask);
-}
-
-static inline sigset_t *sigmask_to_save(void)
-{
-        sigset_t *res = &current->blocked;
-        if (unlikely(test_restore_sigmask()))
-                res = &current->saved_sigmask;
-        return res;
-}
-
-static inline int kill_cad_pid(int sig, int priv)
-{
-        return kill_pid(cad_pid, sig, priv);
-}
-
-/* These can be the second arg to send_sig_info/send_group_sig_info.  */
-#define SEND_SIG_NOINFO ((struct siginfo *) 0)
-#define SEND_SIG_PRIV   ((struct siginfo *) 1)
-#define SEND_SIG_FORCED ((struct siginfo *) 2)
-
-/*
- * True if we are on the alternate signal stack.
- */
-static inline int on_sig_stack(unsigned long sp)
-{
-        /*
-         * If the signal stack is SS_AUTODISARM then, by construction, we
-         * can't be on the signal stack unless user code deliberately set
-         * SS_AUTODISARM when we were already on it.
-         *
-         * This improves reliability: if user state gets corrupted such that
-         * the stack pointer points very close to the end of the signal stack,
-         * then this check will enable the signal to be handled anyway.
-         */
-        if (current->sas_ss_flags & SS_AUTODISARM)
-                return 0;
-
-#ifdef CONFIG_STACK_GROWSUP
-        return sp >= current->sas_ss_sp &&
-                sp - current->sas_ss_sp < current->sas_ss_size;
-#else
-        return sp > current->sas_ss_sp &&
-                sp - current->sas_ss_sp <= current->sas_ss_size;
-#endif
-}
-
-static inline int sas_ss_flags(unsigned long sp)
-{
-        if (!current->sas_ss_size)
-                return SS_DISABLE;
-
-        return on_sig_stack(sp) ? SS_ONSTACK : 0;
-}
-
-static inline void sas_ss_reset(struct task_struct *p)
-{
-        p->sas_ss_sp = 0;
-        p->sas_ss_size = 0;
-        p->sas_ss_flags = SS_DISABLE;
-}
-
-static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
-{
-        if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
-#ifdef CONFIG_STACK_GROWSUP
-                return current->sas_ss_sp;
-#else
-                return current->sas_ss_sp + current->sas_ss_size;
-#endif
-        return sp;
-}
 
 #ifdef CONFIG_HAVE_COPY_THREAD_TLS
 extern int copy_thread_tls(unsigned long, unsigned long, unsigned long,
@@ -2338,10 +1963,8 @@ static inline void exit_thread(struct task_struct *tsk)
 #endif
 
 extern void exit_files(struct task_struct *);
-extern void __cleanup_sighand(struct sighand_struct *);
 
 extern void exit_itimers(struct signal_struct *);
-extern void flush_itimer_signals(void);
 
 extern void do_group_exit(int);
 
@@ -2376,81 +1999,6 @@ static inline unsigned long wait_task_inactive(struct task_struct *p,
 }
 #endif
 
-#define tasklist_empty() \
-        list_empty(&init_task.tasks)
-
-#define next_task(p) \
-        list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
-
-#define for_each_process(p) \
-        for (p = &init_task ; (p = next_task(p)) != &init_task ; )
-
-extern bool current_is_single_threaded(void);
-
-/*
- * Careful: do_each_thread/while_each_thread is a double loop so
- *          'break' will not work as expected - use goto instead.
- */
-#define do_each_thread(g, t) \
-        for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do
-
-#define while_each_thread(g, t) \
-        while ((t = next_thread(t)) != g)
-
-#define __for_each_thread(signal, t)    \
-        list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node)
-
-#define for_each_thread(p, t)           \
-        __for_each_thread((p)->signal, t)
-
-/* Careful: this is a double loop, 'break' won't work as expected. */
-#define for_each_process_thread(p, t)   \
-        for_each_process(p) for_each_thread(p, t)
-
-typedef int (*proc_visitor)(struct task_struct *p, void *data);
-void walk_process_tree(struct task_struct *top, proc_visitor, void *);
-
-static inline int get_nr_threads(struct task_struct *tsk)
-{
-        return tsk->signal->nr_threads;
-}
-
-static inline bool thread_group_leader(struct task_struct *p)
-{
-        return p->exit_signal >= 0;
-}
-
-/* Do to the insanities of de_thread it is possible for a process
- * to have the pid of the thread group leader without actually being
- * the thread group leader.  For iteration through the pids in proc
- * all we care about is that we have a task with the appropriate
- * pid, we don't actually care if we have the right task.
- */
-static inline bool has_group_leader_pid(struct task_struct *p)
-{
-        return task_pid(p) == p->signal->leader_pid;
-}
-
-static inline
-bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
-{
-        return p1->signal == p2->signal;
-}
-
-static inline struct task_struct *next_thread(const struct task_struct *p)
-{
-        return list_entry_rcu(p->thread_group.next,
-                              struct task_struct, thread_group);
-}
-
-static inline int thread_group_empty(struct task_struct *p)
-{
-        return list_empty(&p->thread_group);
-}
-
-#define delay_group_leader(p) \
-                (thread_group_leader(p) && !thread_group_empty(p))
-
 /*
  * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
  * subscriptions and synchronises with wait4().  Also used in procfs.  Also
@@ -2471,25 +2019,6 @@ static inline void task_unlock(struct task_struct *p)
         spin_unlock(&p->alloc_lock);
 }
 
-extern struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
-                                                        unsigned long *flags);
-
-static inline struct sighand_struct *lock_task_sighand(struct task_struct *tsk,
-                                                       unsigned long *flags)
-{
-        struct sighand_struct *ret;
-
-        ret = __lock_task_sighand(tsk, flags);
-        (void)__cond_lock(&tsk->sighand->siglock, ret);
-        return ret;
-}
-
-static inline void unlock_task_sighand(struct task_struct *tsk,
-                                                unsigned long *flags)
-{
-        spin_unlock_irqrestore(&tsk->sighand->siglock, *flags);
-}
-
 #ifdef CONFIG_THREAD_INFO_IN_TASK
 
 static inline struct thread_info *task_thread_info(struct task_struct *task)
@@ -2862,28 +2391,6 @@ static inline void mm_update_next_owner(struct mm_struct *mm)
 }
 #endif /* CONFIG_MEMCG */
 
-static inline unsigned long task_rlimit(const struct task_struct *tsk,
-                unsigned int limit)
-{
-        return READ_ONCE(tsk->signal->rlim[limit].rlim_cur);
-}
-
-static inline unsigned long task_rlimit_max(const struct task_struct *tsk,
-                unsigned int limit)
-{
-        return READ_ONCE(tsk->signal->rlim[limit].rlim_max);
-}
-
-static inline unsigned long rlimit(unsigned int limit)
-{
-        return task_rlimit(current, limit);
-}
-
-static inline unsigned long rlimit_max(unsigned int limit)
-{
-        return task_rlimit_max(current, limit);
-}
-
 #define SCHED_CPUFREQ_RT        (1U << 0)
 #define SCHED_CPUFREQ_DL        (1U << 1)
 #define SCHED_CPUFREQ_IOWAIT    (1U << 2)