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    Subject[PATCH v3 22/27] core: use helpers for rlimits
    Date
    Make sure compiler won't do weird things with limits. E.g. fetching
    them twice may return 2 different values after writable limits are
    implemented.

    I.e. either use newly added rlimit helpers or ACCESS_ONCE if not
    applicable.

    Signed-off-by: Jiri Slaby <jslaby@suse.cz>
    Cc: James Morris <jmorris@namei.org>
    Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Peter Zijlstra <peterz@infradead.org>
    ---
    kernel/fork.c | 10 ++++++----
    kernel/perf_event.c | 2 +-
    kernel/posix-cpu-timers.c | 16 +++++++++-------
    kernel/sched.c | 4 ++--
    kernel/sched_rt.c | 5 +++--
    kernel/signal.c | 2 +-
    kernel/sys.c | 3 +--
    7 files changed, 23 insertions(+), 19 deletions(-)

    diff --git a/kernel/fork.c b/kernel/fork.c
    index 166b8c4..9f0773d 100644
    --- a/kernel/fork.c
    +++ b/kernel/fork.c
    @@ -822,6 +822,8 @@ void __cleanup_sighand(struct sighand_struct *sighand)
    */
    static void posix_cpu_timers_init_group(struct signal_struct *sig)
    {
    + unsigned long cpu_limit;
    +
    /* Thread group counters. */
    thread_group_cputime_init(sig);

    @@ -836,9 +838,9 @@ static void posix_cpu_timers_init_group(struct signal_struct *sig)
    sig->cputime_expires.virt_exp = cputime_zero;
    sig->cputime_expires.sched_exp = 0;

    - if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
    - sig->cputime_expires.prof_exp =
    - secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
    + cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
    + if (cpu_limit != RLIM_INFINITY) {
    + sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit);
    sig->cputimer.running = 1;
    }

    @@ -1028,7 +1030,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
    #endif
    retval = -EAGAIN;
    if (atomic_read(&p->real_cred->user->processes) >=
    - p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
    + task_rlim_get_cur(p, RLIMIT_NPROC)) {
    if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
    p->real_cred->user != INIT_USER)
    goto bad_fork_free;
    diff --git a/kernel/perf_event.c b/kernel/perf_event.c
    index 7f29643..02ba1e0 100644
    --- a/kernel/perf_event.c
    +++ b/kernel/perf_event.c
    @@ -2420,7 +2420,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
    if (user_locked > user_lock_limit)
    extra = user_locked - user_lock_limit;

    - lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
    + lock_limit = rlim_get_cur(RLIMIT_MEMLOCK);
    lock_limit >>= PAGE_SHIFT;
    locked = vma->vm_mm->locked_vm + extra;

    diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
    index a7dcce1..79d4cb3 100644
    --- a/kernel/posix-cpu-timers.c
    +++ b/kernel/posix-cpu-timers.c
    @@ -640,7 +640,7 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
    if (expires_le(sig->it[CPUCLOCK_PROF].expires,
    exp->cpu))
    break;
    - i = sig->rlim[RLIMIT_CPU].rlim_cur;
    + i = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
    if (i != RLIM_INFINITY &&
    i <= cputime_to_secs(exp->cpu))
    break;
    @@ -1032,9 +1032,10 @@ static void check_thread_timers(struct task_struct *tsk,
    /*
    * Check for the special case thread timers.
    */
    - soft = sig->rlim[RLIMIT_RTTIME].rlim_cur;
    + soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
    if (soft != RLIM_INFINITY) {
    - unsigned long hard = sig->rlim[RLIMIT_RTTIME].rlim_max;
    + unsigned long hard = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].
    + rlim_max);

    if (hard != RLIM_INFINITY &&
    tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
    @@ -1122,7 +1123,7 @@ static void check_process_timers(struct task_struct *tsk,
    unsigned long long sum_sched_runtime, sched_expires;
    struct list_head *timers = sig->cpu_timers;
    struct task_cputime cputime;
    - unsigned long cpu_cur_lim = sig->rlim[RLIMIT_CPU].rlim_cur;
    + unsigned long cpu_cur_lim = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);

    /*
    * Don't sample the current process CPU clocks if there are no timers.
    @@ -1198,7 +1199,8 @@ static void check_process_timers(struct task_struct *tsk,

    if (cpu_cur_lim != RLIM_INFINITY) {
    unsigned long psecs = cputime_to_secs(ptime);
    - unsigned long hard = sig->rlim[RLIMIT_CPU].rlim_max;
    + unsigned long hard =
    + ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max);
    cputime_t x;
    if (psecs >= hard) {
    /*
    @@ -1385,7 +1387,7 @@ static inline int fastpath_timer_check(struct task_struct *tsk)
    return 1;
    }

    - return sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY;
    + return ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur) != RLIM_INFINITY;
    }

    /*
    @@ -1483,7 +1485,7 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
    * If the RLIMIT_CPU timer will expire before the
    * ITIMER_PROF timer, we have nothing else to do.
    */
    - if (tsk->signal->rlim[RLIMIT_CPU].rlim_cur
    + if (task_rlim_get_cur(tsk, RLIMIT_CPU)
    < cputime_to_secs(*newval))
    return;
    }
    diff --git a/kernel/sched.c b/kernel/sched.c
    index 3c11ae0..0e4077d 100644
    --- a/kernel/sched.c
    +++ b/kernel/sched.c
    @@ -6072,7 +6072,7 @@ int can_nice(const struct task_struct *p, const int nice)
    /* convert nice value [19,-20] to rlimit style value [1,40] */
    int nice_rlim = 20 - nice;

    - return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur ||
    + return (nice_rlim <= task_rlim_get_cur(p, RLIMIT_NICE) ||
    capable(CAP_SYS_NICE));
    }

    @@ -6257,7 +6257,7 @@ recheck:

    if (!lock_task_sighand(p, &flags))
    return -ESRCH;
    - rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur;
    + rlim_rtprio = task_rlim_get_cur(p, RLIMIT_RTPRIO);
    unlock_task_sighand(p, &flags);

    /* can't set/change the rt policy */
    diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
    index a4d790c..ab41715 100644
    --- a/kernel/sched_rt.c
    +++ b/kernel/sched_rt.c
    @@ -1683,8 +1683,9 @@ static void watchdog(struct rq *rq, struct task_struct *p)
    if (!p->signal)
    return;

    - soft = p->signal->rlim[RLIMIT_RTTIME].rlim_cur;
    - hard = p->signal->rlim[RLIMIT_RTTIME].rlim_max;
    + /* max may change after cur was read, this will be fixed next tick */
    + soft = task_rlim_get_cur(p, RLIMIT_RTTIME);
    + hard = task_rlim_get_max(p, RLIMIT_RTTIME);

    if (soft != RLIM_INFINITY) {
    unsigned long next;
    diff --git a/kernel/signal.c b/kernel/signal.c
    index 6705320..34efd79 100644
    --- a/kernel/signal.c
    +++ b/kernel/signal.c
    @@ -209,7 +209,7 @@ static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
    atomic_inc(&user->sigpending);
    if (override_rlimit ||
    atomic_read(&user->sigpending) <=
    - t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
    + task_rlim_get_cur(t, RLIMIT_SIGPENDING))
    q = kmem_cache_alloc(sigqueue_cachep, flags);
    if (unlikely(q == NULL)) {
    atomic_dec(&user->sigpending);
    diff --git a/kernel/sys.c b/kernel/sys.c
    index fad6010..c4065c5 100644
    --- a/kernel/sys.c
    +++ b/kernel/sys.c
    @@ -572,8 +572,7 @@ static int set_user(struct cred *new)
    return -EINVAL;
    }

    - if (atomic_read(&new_user->processes) >=
    - current->signal->rlim[RLIMIT_NPROC].rlim_cur &&
    + if (atomic_read(&new_user->processes) >= rlim_get_cur(RLIMIT_NPROC) &&
    new_user != INIT_USER) {
    free_uid(new_user);
    return -EAGAIN;
    --
    1.6.5.3


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