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Subject[PATCH 2/2] 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 rlimit helpers added in
3e10e716abf3c71bdb5d86b8f507f9e72236c9cd
or ACCESS_ONCE if not applicable.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
kernel/fork.c | 10 ++++++----
kernel/perf_event.c | 2 +-
kernel/posix-cpu-timers.c | 10 ++++++----
kernel/sched.c | 4 ++--
kernel/sched_rt.c | 5 +++--
kernel/signal.c | 2 +-
kernel/sys.c | 3 +--
7 files changed, 20 insertions(+), 16 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index 3d66564..6fca655 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -824,12 +824,14 @@ 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);

- 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;
}

@@ -999,7 +1001,7 @@ 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 f1d4b25..0da8415 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2481,7 +2481,7 @@ 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 417fe38..fd6ea9b 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -966,9 +966,10 @@ 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)) {
@@ -1130,10 +1131,11 @@ 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 854dd03..c8fd5e1 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6141,7 +6141,7 @@ 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));
}

@@ -6318,7 +6318,7 @@ 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 072b3fc..5a86793 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1670,8 +1670,9 @@ 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 278704b..2213bb4 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -228,7 +228,7 @@ __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 ef286ab..c9da91a 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -574,8 +574,7 @@ 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) >= rlimit(RLIMIT_NPROC) &&
new_user != INIT_USER) {
free_uid(new_user);
return -EAGAIN;
--
1.6.6.1


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