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    Subject[PATCH ghak90 V7 15/21] sched: pull task_is_descendant into kernel/sched/core.c
    Date
    Since the task_is_descendant() function is used in YAMA and in audit,
    pull the function into kernel/core/sched.c

    Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
    ---
    include/linux/sched.h | 3 +++
    kernel/audit.c | 33 ---------------------------------
    kernel/sched/core.c | 33 +++++++++++++++++++++++++++++++++
    security/yama/yama_lsm.c | 33 ---------------------------------
    4 files changed, 36 insertions(+), 66 deletions(-)

    diff --git a/include/linux/sched.h b/include/linux/sched.h
    index a936d162513a..b251f018f4db 100644
    --- a/include/linux/sched.h
    +++ b/include/linux/sched.h
    @@ -1988,4 +1988,7 @@ static inline void rseq_syscall(struct pt_regs *regs)

    const struct cpumask *sched_trace_rd_span(struct root_domain *rd);

    +extern int task_is_descendant(struct task_struct *parent,
    + struct task_struct *child);
    +
    #endif
    diff --git a/kernel/audit.c b/kernel/audit.c
    index 69fe1e9af7cb..4fe7678304dd 100644
    --- a/kernel/audit.c
    +++ b/kernel/audit.c
    @@ -2560,39 +2560,6 @@ static struct task_struct *audit_cont_owner(struct task_struct *tsk)
    }

    /*
    - * task_is_descendant - walk up a process family tree looking for a match
    - * @parent: the process to compare against while walking up from child
    - * @child: the process to start from while looking upwards for parent
    - *
    - * Returns 1 if child is a descendant of parent, 0 if not.
    - */
    -static int task_is_descendant(struct task_struct *parent,
    - struct task_struct *child)
    -{
    - int rc = 0;
    - struct task_struct *walker = child;
    -
    - if (!parent || !child)
    - return 0;
    -
    - rcu_read_lock();
    - if (!thread_group_leader(parent))
    - parent = rcu_dereference(parent->group_leader);
    - while (walker->pid > 0) {
    - if (!thread_group_leader(walker))
    - walker = rcu_dereference(walker->group_leader);
    - if (walker == parent) {
    - rc = 1;
    - break;
    - }
    - walker = rcu_dereference(walker->real_parent);
    - }
    - rcu_read_unlock();
    -
    - return rc;
    -}
    -
    -/*
    * audit_set_contid - set current task's audit contid
    * @task: target task
    * @contid: contid value
    diff --git a/kernel/sched/core.c b/kernel/sched/core.c
    index 2b037f195473..7ba9e07381fa 100644
    --- a/kernel/sched/core.c
    +++ b/kernel/sched/core.c
    @@ -7509,6 +7509,39 @@ void dump_cpu_task(int cpu)
    }

    /*
    + * task_is_descendant - walk up a process family tree looking for a match
    + * @parent: the process to compare against while walking up from child
    + * @child: the process to start from while looking upwards for parent
    + *
    + * Returns 1 if child is a descendant of parent, 0 if not.
    + */
    +int task_is_descendant(struct task_struct *parent,
    + struct task_struct *child)
    +{
    + int rc = 0;
    + struct task_struct *walker = child;
    +
    + if (!parent || !child)
    + return 0;
    +
    + rcu_read_lock();
    + if (!thread_group_leader(parent))
    + parent = rcu_dereference(parent->group_leader);
    + while (walker->pid > 0) {
    + if (!thread_group_leader(walker))
    + walker = rcu_dereference(walker->group_leader);
    + if (walker == parent) {
    + rc = 1;
    + break;
    + }
    + walker = rcu_dereference(walker->real_parent);
    + }
    + rcu_read_unlock();
    +
    + return rc;
    +}
    +
    +/*
    * Nice levels are multiplicative, with a gentle 10% change for every
    * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
    * nice 1, it will get ~10% less CPU time than another CPU-bound task
    diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
    index 94dc346370b1..25eae205eae8 100644
    --- a/security/yama/yama_lsm.c
    +++ b/security/yama/yama_lsm.c
    @@ -263,39 +263,6 @@ static int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3,
    }

    /**
    - * task_is_descendant - walk up a process family tree looking for a match
    - * @parent: the process to compare against while walking up from child
    - * @child: the process to start from while looking upwards for parent
    - *
    - * Returns 1 if child is a descendant of parent, 0 if not.
    - */
    -static int task_is_descendant(struct task_struct *parent,
    - struct task_struct *child)
    -{
    - int rc = 0;
    - struct task_struct *walker = child;
    -
    - if (!parent || !child)
    - return 0;
    -
    - rcu_read_lock();
    - if (!thread_group_leader(parent))
    - parent = rcu_dereference(parent->group_leader);
    - while (walker->pid > 0) {
    - if (!thread_group_leader(walker))
    - walker = rcu_dereference(walker->group_leader);
    - if (walker == parent) {
    - rc = 1;
    - break;
    - }
    - walker = rcu_dereference(walker->real_parent);
    - }
    - rcu_read_unlock();
    -
    - return rc;
    -}
    -
    -/**
    * ptracer_exception_found - tracer registered as exception for this tracee
    * @tracer: the task_struct of the process attempting ptrace
    * @tracee: the task_struct of the process to be ptraced
    --
    1.8.3.1
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