kernel core: use helpers for rlimits

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 rlimit helpers added in commit 3e10e716abf3 ("resource:
add helpers for fetching rlimits") or ACCESS_ONCE if not applicable.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

7 files changed, 20 insertions, 16 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index bab7b254ad39..b0ec34abc0bb 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -828,6 +828,8 @@ 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);
 
@@ -842,9 +844,9 @@ 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;
         }
 
@@ -1037,7 +1039,7 @@ 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_rlimit(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 a661e7991865..8e352c756ba7 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2610,7 +2610,7 @@ 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 = rlimit(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 dbb16bf15c45..1a22dfd42df9 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -1031,9 +1031,10 @@ 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)) {
@@ -1194,10 +1195,11 @@ static void check_process_timers(struct task_struct *tsk,
                          SIGPROF);
         check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
                          SIGVTALRM);
-        soft = sig->rlim[RLIMIT_CPU].rlim_cur;
+        soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
         if (soft != 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) {
                         /*
diff --git a/kernel/sched.c b/kernel/sched.c
index abb36b16b93b..b47ceeec1a91 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4353,7 +4353,7 @@ 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_rlimit(p, RLIMIT_NICE) ||
                 capable(CAP_SYS_NICE));
 }
 
@@ -4530,7 +4530,7 @@ recheck:
 
                         if (!lock_task_sighand(p, &flags))
                                 return -ESRCH;
-                        rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur;
+                        rlim_rtprio = task_rlimit(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 bf3e38fdbe6d..5a6ed1f0990a 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1662,8 +1662,9 @@ 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_rlimit(p, RLIMIT_RTTIME);
+        hard = task_rlimit_max(p, RLIMIT_RTTIME);
 
         if (soft != RLIM_INFINITY) {
                 unsigned long next;
diff --git a/kernel/signal.c b/kernel/signal.c
index 5bb9baffa4f1..dbd7fe073c55 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -245,7 +245,7 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimi
 
         if (override_rlimit ||
             atomic_read(&user->sigpending) <=
-                        t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur) {
+                        task_rlimit(t, RLIMIT_SIGPENDING)) {
                 q = kmem_cache_alloc(sigqueue_cachep, flags);
         } else {
                 print_dropped_signal(sig);
diff --git a/kernel/sys.c b/kernel/sys.c
index 877fe4f8e05e..9814e43fb23b 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -571,8 +571,7 @@ static int set_user(struct cred *new)
         if (!new_user)
                 return -EAGAIN;
 
-        if (atomic_read(&new_user->processes) >=
-                                current->signal->rlim[RLIMIT_NPROC].rlim_cur &&
+        if (atomic_read(&new_user->processes) >= rlimit(RLIMIT_NPROC) &&
                         new_user != INIT_USER) {
                 free_uid(new_user);
                 return -EAGAIN;