[PATCH] ipv4 : igmp : optimize timer modify logic in igmp_mod_timer()

Subsystems: networking [general], networking [ipv4/ipv6], the rest

STALE5386d

3 messages, 2 authors, 2011-11-23 · open the first message on its own page

[PATCH] ipv4 : igmp : optimize timer modify logic in igmp_mod_timer()

From: Jun Zhao <hidden>
Date: 2011-11-23 15:28:02

When timer is pending and expires less-than-or-equal-to new delay,
we need not used del_timer()/add_timer().

Signed-off-by: Jun Zhao <redacted>
---
 net/ipv4/igmp.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index c7472ef..50d06c5 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c

@@ -215,14 +215,14 @@ static void igmp_mod_timer(struct ip_mc_list *im, int max_delay)
 {
 	spin_lock_bh(&im->lock);
 	im->unsolicit_count = 0;
-	if (del_timer(&im->timer)) {
-		if ((long)(im->timer.expires-jiffies) < max_delay) {
-			add_timer(&im->timer);
-			im->tm_running = 1;
-			spin_unlock_bh(&im->lock);
+	if (timer_pending(&im->timer)) {
+		if (time_before_eq(im->timer.expires, (jiffies + max_delay))) {
+			spin_lock_bh(&im->lock);
 			return;
+		} else {
+			del_timer(&im->timer);
+			atomic_dec(&im->refcnt);
 		}
-		atomic_dec(&im->refcnt);
 	}
 	igmp_start_timer(im, max_delay);
 	spin_unlock_bh(&im->lock);

-- 
1.7.2.5

Re: [PATCH] ipv4 : igmp : optimize timer modify logic in igmp_mod_timer()

From: Eric Dumazet <hidden>
Date: 2011-11-23 15:42:50

Le mercredi 23 novembre 2011 à 23:26 +0800, Jun Zhao a écrit :

quoted hunk

When timer is pending and expires less-than-or-equal-to new delay,
we need not used del_timer()/add_timer().

Signed-off-by: Jun Zhao <redacted>
---
 net/ipv4/igmp.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index c7472ef..50d06c5 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c

@@ -215,14 +215,14 @@ static void igmp_mod_timer(struct ip_mc_list *im, int max_delay)
 {
 	spin_lock_bh(&im->lock);
 	im->unsolicit_count = 0;
-	if (del_timer(&im->timer)) {
-		if ((long)(im->timer.expires-jiffies) < max_delay) {
-			add_timer(&im->timer);
-			im->tm_running = 1;
-			spin_unlock_bh(&im->lock);
+	if (timer_pending(&im->timer)) {
+		if (time_before_eq(im->timer.expires, (jiffies + max_delay))) {
+			spin_lock_bh(&im->lock);

And you actually tested this patch ?

 			return;
+		} else {
+			del_timer(&im->timer);
+			atomic_dec(&im->refcnt);
 		}
-		atomic_dec(&im->refcnt);
 	}
 	igmp_start_timer(im, max_delay);
 	spin_unlock_bh(&im->lock);


Not sure why you want to optimize this very rare function call, risking
adding bugs in it.

Re: [PATCH] ipv4 : igmp : optimize timer modify logic in igmp_mod_timer()

From: Jun Zhao <hidden>
Date: 2011-11-23 15:45:25

On Wed, 2011-11-23 at 16:42 +0100, Eric Dumazet wrote:

Le mercredi 23 novembre 2011 à 23:26 +0800, Jun Zhao a écrit :

quoted

When timer is pending and expires less-than-or-equal-to new delay,
we need not used del_timer()/add_timer().

Signed-off-by: Jun Zhao <redacted>
---
 net/ipv4/igmp.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index c7472ef..50d06c5 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c

@@ -215,14 +215,14 @@ static void igmp_mod_timer(struct ip_mc_list *im, int max_delay)
 {
 	spin_lock_bh(&im->lock);
 	im->unsolicit_count = 0;
-	if (del_timer(&im->timer)) {
-		if ((long)(im->timer.expires-jiffies) < max_delay) {
-			add_timer(&im->timer);
-			im->tm_running = 1;
-			spin_unlock_bh(&im->lock);
+	if (timer_pending(&im->timer)) {
+		if (time_before_eq(im->timer.expires, (jiffies + max_delay))) {
+			spin_lock_bh(&im->lock);

And you actually tested this patch ?

Sorry for this mistake. :(.  spin_lock_bh -> spin_unlock_bh

quoted

 			return;
+		} else {
+			del_timer(&im->timer);
+			atomic_dec(&im->refcnt);
 		}
-		atomic_dec(&im->refcnt);
 	}
 	igmp_start_timer(im, max_delay);
 	spin_unlock_bh(&im->lock);


Not sure why you want to optimize this very rare function call, risking
adding bugs in it.

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