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[PATCH v2 1/3] scsi: drop unlikely behind BUG_ON()

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  [PATCH v2 1/3] scsi: drop unlikely behind BUG_ON() Geliang Tang <geliangtang@163.com> - 2015-10-05 15:30 +0200
    [PATCH v2 2/3] sched/core: drop unlikely behind BUG_ON() Geliang Tang <geliangtang@163.com> - 2015-10-05 15:30 +0200
      [tip:sched/core] sched/core: Drop unlikely behind BUG_ON() tip-bot for Geliang Tang <tipbot@zytor.com> - 2015-10-06 18:20 +0200
    [PATCH v2 3/3] mm/nommu: drop unlikely behind BUG_ON() Geliang Tang <geliangtang@163.com> - 2015-10-05 15:40 +0200

#1239555 — [PATCH v2 1/3] scsi: 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>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
---
Changes in v2:
 - Just rewrite the commit log.
---
 drivers/scsi/scsi_lib.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index f570b48..3b5faab 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1164,8 +1164,8 @@ int scsi_init_io(struct scsi_cmnd *cmd)
 
 		count = blk_rq_map_integrity_sg(rq->q, rq->bio,
 						prot_sdb->table.sgl);
-		BUG_ON(unlikely(count > ivecs));
-		BUG_ON(unlikely(count > queue_max_integrity_segments(rq->q)));
+		BUG_ON(count > ivecs);
+		BUG_ON(count > queue_max_integrity_segments(rq->q));
 
 		cmd->prot_sdb = prot_sdb;
 		cmd->prot_sdb->table.nents = count;
-- 
2.5.0


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#1239557 — [PATCH v2 2/3] 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>
---
Changes in v2:
 - Just rewrite the commit log.
---
 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 fe81929..a3518789 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2947,7 +2947,7 @@ 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
 	/*
 	 * Test if we are atomic. Since do_exit() needs to call into
-- 
2.5.0


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#1240636 — [tip:sched/core] sched/core: Drop unlikely behind BUG_ON()

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())) {
--
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#1239567 — [PATCH v2 3/3] mm/nommu: 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>
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


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