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SubjectRe: [PATCH 1/1] kernel core: use helpers for rlimits fix
On Wed, 10 Feb 2010 20:59:08 +0100
Jiri Slaby <jslaby@suse.cz> wrote:

> This is unmerged part of
> kernel-core-use-helpers-for-rlimits.patch
>
> Please amend.
>
> --
>
> 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 | 8 +++++---
> 1 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 11a84db..13ec487 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -828,12 +828,14 @@ 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;
> }

problem is, this patch is all tangled up with
copy_signal-cleanup-clean-thread_group_cputime_init.patch.

I changed the above fix to be:

--- a/kernel/fork.c~kernel-core-use-helpers-for-rlimits-fix
+++ a/kernel/fork.c
@@ -827,6 +827,8 @@ void __cleanup_sighand(struct sighand_st
*/
static void posix_cpu_timers_init_group(struct signal_struct *sig)
{
+ unsigned long cpu_limit;
+
/* Thread group counters. */
thread_group_cputime_init(sig);

@@ -841,9 +843,9 @@ static void posix_cpu_timers_init_group(
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;
}

_
and mangled
copy_signal-cleanup-clean-thread_group_cputime_init.patch to suit:

From: Veaceslav Falico <vfalico@redhat.com>

Remove unneeded initializations in thread_group_cputime_init() and in
posix_cpu_timers_init_group(). They are useless after kmem_cache_zalloc()
was used in copy_signal().

Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/sched.h | 2 --
kernel/fork.c | 11 -----------
2 files changed, 13 deletions(-)
diff -puN include/linux/sched.h~copy_signal-cleanup-clean-thread_group_cputime_init include/linux/sched.h
--- a/include/linux/sched.h~copy_signal-cleanup-clean-thread_group_cputime_init
+++ a/include/linux/sched.h
@@ -2394,9 +2394,7 @@ void thread_group_cputimer(struct task_s

static inline void thread_group_cputime_init(struct signal_struct *sig)
{
- sig->cputimer.cputime = INIT_CPUTIME;
spin_lock_init(&sig->cputimer.lock);
- sig->cputimer.running = 0;
}

static inline void thread_group_cputime_free(struct signal_struct *sig)
diff -puN kernel/fork.c~copy_signal-cleanup-clean-thread_group_cputime_init kernel/fork.c
--- a/kernel/fork.c~copy_signal-cleanup-clean-thread_group_cputime_init
+++ a/kernel/fork.c
@@ -833,17 +833,6 @@ static void posix_cpu_timers_init_group(
/* Thread group counters. */
thread_group_cputime_init(sig);

- /* Expiration times and increments. */
- sig->it[CPUCLOCK_PROF].expires = cputime_zero;
- sig->it[CPUCLOCK_PROF].incr = cputime_zero;
- sig->it[CPUCLOCK_VIRT].expires = cputime_zero;
- sig->it[CPUCLOCK_VIRT].incr = cputime_zero;
-
- /* Cached expiration times. */
- sig->cputime_expires.prof_exp = cputime_zero;
- sig->cputime_expires.virt_exp = cputime_zero;
- sig->cputime_expires.sched_exp = 0;
-
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);
_
Resulting in:

static void posix_cpu_timers_init_group(struct signal_struct *sig)
{
unsigned long cpu_limit;
/* Thread group counters. */
thread_group_cputime_init(sig);
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;
}
/* The timer lists. */
INIT_LIST_HEAD(&sig->cpu_timers[0]);
INIT_LIST_HEAD(&sig->cpu_timers[1]);
INIT_LIST_HEAD(&sig->cpu_timers[2]);
}


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