* [PATCH v2 3/3] mm/nommu: drop unlikely behind BUG_ON()
2015-10-05 13:26 ` [PATCH v2 2/3] sched/core: " Geliang Tang
@ 2015-10-05 13:26 ` Geliang Tang
2015-10-06 16:17 ` [tip:sched/core] sched/core: Drop " tip-bot for Geliang Tang
1 sibling, 0 replies; 4+ messages in thread
From: Geliang Tang @ 2015-10-05 13:26 UTC (permalink / raw)
To: Andrew Morton, Kirill A. Shutemov, Hugh Dickins,
Peter Zijlstra (Intel),
Andrea Arcangeli, Davidlohr Bueso, Joonsoo Kim, Paul Gortmaker,
Leon Romanovsky, Oleg Nesterov
Cc: Geliang Tang, linux-mm, linux-kernel
(1) For !CONFIG_BUG cases, the bug call is a no-op, so we couldn't care
less and the change is ok.
(2) ppc and mips, which HAVE_ARCH_BUG_ON, do not rely on branch predictions
as it seems to be pointless[1] and thus callers should not be trying to
push an optimization in the first place.
(3) For CONFIG_BUG and !HAVE_ARCH_BUG_ON cases, BUG_ON() contains an
unlikely compiler flag already.
Hence, we can drop unlikely behind BUG_ON().
[1] http://lkml.iu.edu/hypermail/linux/kernel/1101.3/02289.html
Signed-off-by: Geliang Tang <geliangtang@163.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
---
Changes in v2:
- Just rewrite the commit log.
---
mm/nommu.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/mm/nommu.c b/mm/nommu.c
index 1e0f168..92be862 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -578,16 +578,16 @@ static noinline void validate_nommu_regions(void)
return;
last = rb_entry(lastp, struct vm_region, vm_rb);
- BUG_ON(unlikely(last->vm_end <= last->vm_start));
- BUG_ON(unlikely(last->vm_top < last->vm_end));
+ BUG_ON(last->vm_end <= last->vm_start);
+ BUG_ON(last->vm_top < last->vm_end);
while ((p = rb_next(lastp))) {
region = rb_entry(p, struct vm_region, vm_rb);
last = rb_entry(lastp, struct vm_region, vm_rb);
- BUG_ON(unlikely(region->vm_end <= region->vm_start));
- BUG_ON(unlikely(region->vm_top < region->vm_end));
- BUG_ON(unlikely(region->vm_start < last->vm_top));
+ BUG_ON(region->vm_end <= region->vm_start);
+ BUG_ON(region->vm_top < region->vm_end);
+ BUG_ON(region->vm_start < last->vm_top);
lastp = p;
}
--
2.5.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [tip:sched/core] sched/core: Drop unlikely behind BUG_ON()
2015-10-05 13:26 ` [PATCH v2 2/3] sched/core: " Geliang Tang
2015-10-05 13:26 ` [PATCH v2 3/3] mm/nommu: " Geliang Tang
@ 2015-10-06 16:17 ` tip-bot for Geliang Tang
1 sibling, 0 replies; 4+ messages in thread
From: tip-bot for Geliang Tang @ 2015-10-06 16:17 UTC (permalink / raw)
To: linux-tip-commits
Cc: efault, peterz, hpa, linux-kernel, torvalds, geliangtang, mingo, tglx
Commit-ID: ce03e4137bb22fc560ad7a07cf4138ae2cd59f65
Gitweb: http://git.kernel.org/tip/ce03e4137bb22fc560ad7a07cf4138ae2cd59f65
Author: Geliang Tang <geliangtang@163.com>
AuthorDate: Mon, 5 Oct 2015 21:26:05 +0800
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 6 Oct 2015 17:08:22 +0200
sched/core: Drop unlikely behind BUG_ON()
(1) For !CONFIG_BUG cases, the bug call is a no-op, so we couldn't care
less and the change is ok.
(2) PPC and MIPS, which HAVE_ARCH_BUG_ON, do not rely on branch predictions
as it seems to be pointless [1] and thus callers should not be trying to
push an optimization in the first place.
(3) For CONFIG_BUG and !HAVE_ARCH_BUG_ON cases, BUG_ON() contains an
unlikely compiler flag already.
Hence, we can drop unlikely behind BUG_ON().
[1] http://lkml.iu.edu/hypermail/linux/kernel/1101.3/02289.html
Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/6fa7125979f98bbeac26e268271769b6ca935c8d.1444051018.git.geliangtang@163.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fb14a01..a395db1 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2971,7 +2971,7 @@ static noinline void __schedule_bug(struct task_struct *prev)
static inline void schedule_debug(struct task_struct *prev)
{
#ifdef CONFIG_SCHED_STACK_END_CHECK
- BUG_ON(unlikely(task_stack_end_corrupted(prev)));
+ BUG_ON(task_stack_end_corrupted(prev));
#endif
if (unlikely(in_atomic_preempt_off())) {
^ permalink raw reply related [flat|nested] 4+ messages in thread