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srcu: fix misprint in srcu_funnel_exp_start

PATCH In review Ildar Ismagilov 2 participants 3 messages Jan 29, 2018 – Jan 30, 2018 Sleepable read-copy update (SRCU)

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Ildar Ismagilov

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#0 lore raw

PATCH 1/1 srcu: fix misprint in srcu_funnel_exp_start

Signed-off-by Ildar Ismagilov <[email protected]>
---
 kernel/rcu/srcutree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
kernel/rcu/srcutree.c +1 -1
index 6d5880089ff6..1798d1aa60fa 100644
@@ -599,7 +599,7 @@ static void srcu_funnel_exp_start(struct srcu_struct *sp, struct srcu_node *snp,
 		raw_spin_unlock_irqrestore_rcu_node(snp, flags);
 	}
 	raw_spin_lock_irqsave_rcu_node(sp, flags);
-	if (!ULONG_CMP_LT(sp->srcu_gp_seq_needed_exp, s))
+	if (ULONG_CMP_LT(sp->srcu_gp_seq_needed_exp, s))
 		sp->srcu_gp_seq_needed_exp = s;
 	raw_spin_unlock_irqrestore_rcu_node(sp, flags);
 }
Signature · 1 line
2.11.0
#1 lore raw
Quoted 1 line · Ildar Ismagilov
Signed-off-by Ildar Ismagilov <[email protected]>

The original does look backwards, now that you mention it, thank you for sending it.

Did you see any performance differences from this patch?

Thanx, Paul

Quoted 20 lines
---
 kernel/rcu/srcutree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
kernel/rcu/srcutree.c +1 -1
index 6d5880089ff6..1798d1aa60fa 100644
@@ -599,7 +599,7 @@ static void srcu_funnel_exp_start(struct srcu_struct *sp, struct srcu_node *snp,
 		raw_spin_unlock_irqrestore_rcu_node(snp, flags);
 	}
 	raw_spin_lock_irqsave_rcu_node(sp, flags);
-	if (!ULONG_CMP_LT(sp->srcu_gp_seq_needed_exp, s))
+	if (ULONG_CMP_LT(sp->srcu_gp_seq_needed_exp, s))
 		sp->srcu_gp_seq_needed_exp = s;
 	raw_spin_unlock_irqrestore_rcu_node(sp, flags);
 }
Signature · 1 line
2.11.0
author
#2 lore raw

I didn't check the performance, because this misprint has been found accidentally, during studying of a RCU/SRCU code.

2018-01-30 8:37 GMT+03:00 Paul E. McKenney <[email protected]>:

Quoted 31 lines · Ildar Ismagilov
Quoted 1 line
Signed-off-by Ildar Ismagilov <[email protected]>

The original does look backwards, now that you mention it, thank you for sending it.

Did you see any performance differences from this patch?

Thanx, Paul

Quoted 20 lines
---
 kernel/rcu/srcutree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
kernel/rcu/srcutree.c +1 -2
index 6d5880089ff6..1798d1aa60fa 100644
@@ -599,7 +599,7 @@ static void srcu_funnel_exp_start(struct srcu_struct *sp, struct srcu_node *snp,
              raw_spin_unlock_irqrestore_rcu_node(snp, flags);
      }
      raw_spin_lock_irqsave_rcu_node(sp, flags);
-     if (!ULONG_CMP_LT(sp->srcu_gp_seq_needed_exp, s))
+     if (ULONG_CMP_LT(sp->srcu_gp_seq_needed_exp, s))
              sp->srcu_gp_seq_needed_exp = s;
      raw_spin_unlock_irqrestore_rcu_node(sp, flags);
 }
--

2.11.0

Signature · 2 lines
Best regards
Ildar