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    Subject[PATCH 10/19] signal: remove three noop tracehooks
    Date
    Remove the following three noop tracehooks in signals.c.

    * tracehook_force_sigpending()
    * tracehook_get_signal()
    * tracehook_finish_jctl()

    The code area is about to be updated and these hooks don't do anything
    other than obfuscating the logic.

    Signed-off-by: Tejun Heo <tj@kernel.org>
    ---
    include/linux/tracehook.h | 52 ---------------------------------------------
    kernel/signal.c | 44 ++++++++++++--------------------------
    2 files changed, 14 insertions(+), 82 deletions(-)

    diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
    index e95f523..15745cd 100644
    --- a/include/linux/tracehook.h
    +++ b/include/linux/tracehook.h
    @@ -425,58 +425,6 @@ static inline int tracehook_consider_fatal_signal(struct task_struct *task,
    return (task_ptrace(task) & PT_PTRACED) != 0;
    }

    -/**
    - * tracehook_force_sigpending - let tracing force signal_pending(current) on
    - *
    - * Called when recomputing our signal_pending() flag. Return nonzero
    - * to force the signal_pending() flag on, so that tracehook_get_signal()
    - * will be called before the next return to user mode.
    - *
    - * Called with @current->sighand->siglock held.
    - */
    -static inline int tracehook_force_sigpending(void)
    -{
    - return 0;
    -}
    -
    -/**
    - * tracehook_get_signal - deliver synthetic signal to traced task
    - * @task: @current
    - * @regs: task_pt_regs(@current)
    - * @info: details of synthetic signal
    - * @return_ka: sigaction for synthetic signal
    - *
    - * Return zero to check for a real pending signal normally.
    - * Return -1 after releasing the siglock to repeat the check.
    - * Return a signal number to induce an artificial signal delivery,
    - * setting *@info and *@return_ka to specify its details and behavior.
    - *
    - * The @return_ka->sa_handler value controls the disposition of the
    - * signal, no matter the signal number. For %SIG_DFL, the return value
    - * is a representative signal to indicate the behavior (e.g. %SIGTERM
    - * for death, %SIGQUIT for core dump, %SIGSTOP for job control stop,
    - * %SIGTSTP for stop unless in an orphaned pgrp), but the signal number
    - * reported will be @info->si_signo instead.
    - *
    - * Called with @task->sighand->siglock held, before dequeuing pending signals.
    - */
    -static inline int tracehook_get_signal(struct task_struct *task,
    - struct pt_regs *regs,
    - siginfo_t *info,
    - struct k_sigaction *return_ka)
    -{
    - return 0;
    -}
    -
    -/**
    - * tracehook_finish_jctl - report about return from job control stop
    - *
    - * This is called by do_signal_stop() after wakeup.
    - */
    -static inline void tracehook_finish_jctl(void)
    -{
    -}
    -
    #define DEATH_REAP -1
    #define DEATH_DELAYED_GROUP_LEADER -2

    diff --git a/kernel/signal.c b/kernel/signal.c
    index 106b47e..85df25e 100644
    --- a/kernel/signal.c
    +++ b/kernel/signal.c
    @@ -150,9 +150,7 @@ void recalc_sigpending_and_wake(struct task_struct *t)

    void recalc_sigpending(void)
    {
    - if (unlikely(tracehook_force_sigpending()))
    - set_thread_flag(TIF_SIGPENDING);
    - else if (!recalc_sigpending_tsk(current) && !freezing(current))
    + if (!recalc_sigpending_tsk(current) && !freezing(current))
    clear_thread_flag(TIF_SIGPENDING);

    }
    @@ -2005,8 +2003,6 @@ retry:

    spin_unlock_irq(&current->sighand->siglock);

    - tracehook_finish_jctl();
    -
    return 1;
    }

    @@ -2109,37 +2105,25 @@ relock:

    for (;;) {
    struct k_sigaction *ka;
    - /*
    - * Tracing can induce an artificial signal and choose sigaction.
    - * The return value in @signr determines the default action,
    - * but @info->si_signo is the signal number we will report.
    - */
    - signr = tracehook_get_signal(current, regs, info, return_ka);
    - if (unlikely(signr < 0))
    +
    + if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
    + do_signal_stop(0))
    goto relock;
    - if (unlikely(signr != 0))
    - ka = return_ka;
    - else {
    - if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
    - do_signal_stop(0))
    - goto relock;

    - signr = dequeue_signal(current, &current->blocked,
    - info);
    + signr = dequeue_signal(current, &current->blocked, info);

    - if (!signr)
    - break; /* will return 0 */
    + if (!signr)
    + break; /* will return 0 */

    - if (signr != SIGKILL) {
    - signr = ptrace_signal(signr, info,
    - regs, cookie);
    - if (!signr)
    - continue;
    - }
    -
    - ka = &sighand->action[signr-1];
    + if (signr != SIGKILL) {
    + signr = ptrace_signal(signr, info,
    + regs, cookie);
    + if (!signr)
    + continue;
    }

    + ka = &sighand->action[signr-1];
    +
    /* Trace actually delivered signals. */
    trace_signal_deliver(signr, info, ka);

    --
    1.7.1


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