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Date: Wed, 18 Nov 2009 15:51:56 +0100
From: Jiri Slaby <jslaby@...ell.com>
To: jirislaby@...il.com
Cc: mingo@...e.hu, nhorman@...driver.com, sfr@...b.auug.org.au,
linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
marcin.slusarz@...il.com, tglx@...utronix.de, mingo@...hat.com,
hpa@...or.com, torvalds@...ux-foundation.org,
Jiri Slaby <jslaby@...ell.com>,
James Morris <jmorris@...ei.org>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH 10/16] core: use ACCESS_ONCE 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.
Signed-off-by: Jiri Slaby <jslaby@...ell.com>
Cc: James Morris <jmorris@...ei.org>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Peter Zijlstra <peterz@...radead.org>
---
kernel/fork.c | 10 ++++++----
kernel/perf_event.c | 3 ++-
kernel/posix-cpu-timers.c | 16 +++++++++-------
kernel/sched.c | 6 ++++--
kernel/sched_rt.c | 5 +++--
kernel/signal.c | 4 ++--
kernel/sys.c | 4 ++--
7 files changed, 28 insertions(+), 20 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index 166b8c4..dab13f2 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) {
+ ACCESS_ONCE(p->signal->rlim[RLIMIT_NPROC].rlim_cur)) {
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..229ce9a 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2420,7 +2420,8 @@ 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 = ACCESS_ONCE(current->signal->
+ rlim[RLIMIT_MEMLOCK].rlim_cur);
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..4c11521 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 (ACCESS_ONCE(tsk->signal->rlim[RLIMIT_CPU].rlim_cur)
< cputime_to_secs(*newval))
return;
}
diff --git a/kernel/sched.c b/kernel/sched.c
index 3c11ae0..15172ea 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6072,7 +6072,8 @@ 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 <= ACCESS_ONCE(p->signal->
+ rlim[RLIMIT_NICE].rlim_cur) ||
capable(CAP_SYS_NICE));
}
@@ -6257,7 +6258,8 @@ recheck:
if (!lock_task_sighand(p, &flags))
return -ESRCH;
- rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur;
+ rlim_rtprio = ACCESS_ONCE(p->signal->
+ rlim[RLIMIT_RTPRIO].rlim_cur);
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..99d4490 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 = ACCESS_ONCE(p->signal->rlim[RLIMIT_RTTIME].rlim_cur);
+ hard = ACCESS_ONCE(p->signal->rlim[RLIMIT_RTTIME].rlim_max);
if (soft != RLIM_INFINITY) {
unsigned long next;
diff --git a/kernel/signal.c b/kernel/signal.c
index 6705320..e33ece0 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -208,8 +208,8 @@ static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
user = get_uid(__task_cred(t)->user);
atomic_inc(&user->sigpending);
if (override_rlimit ||
- atomic_read(&user->sigpending) <=
- t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
+ atomic_read(&user->sigpending) <= ACCESS_ONCE(t->signal->
+ rlim[RLIMIT_SIGPENDING].rlim_cur))
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 0f86199..52200d4 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -572,8 +572,8 @@ 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) >= ACCESS_ONCE(current->signal->
+ rlim[RLIMIT_NPROC].rlim_cur) &&
new_user != INIT_USER) {
free_uid(new_user);
return -EAGAIN;
--
1.6.4.2
--
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