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ktime: helpers to convert between ktime and jiffies

PATCH New Tejaswi Tanikella 2 participants 3 messages Jun 11, 2018 – Jun 20, 2018

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Tejaswi Tanikella

author
#0 lore raw

PATCH v3 1/2 ktime: helpers to convert between ktime and jiffies

Signed-off-by Tejaswi Tanikella <[email protected]>

---
v2: use alarmtimer instead of wakelock.
v3: add patches in the right order.

---
 include/linux/ktime.h | 4 ++++
 1 file changed, 4 insertions(+)
include/linux/ktime.h +4 -0
index 5b9fddb..4881483 100644
@@ -96,6 +96,10 @@ static inline ktime_t timeval_to_ktime(struct timeval tv)
 /* Convert ktime_t to nanoseconds - NOP in the scalar storage format: */
 #define ktime_to_ns(kt)			(kt)
 
+/* ktime to jiffies and back */
+#define ktime_to_jiffies(kt)		nsecs_to_jiffies(kt)
+#define jiffies_to_ktime(j)		jiffies_to_nsecs(j)
+
 /**
  * ktime_compare - Compares two ktime_t variables for less, greater or equal
  * @cmp1:	comparable1
Signature · 1 line
1.9.1
author
#1 lore raw

PATCH v3 2/2 ipv4: igmp: use alarmtimer to prevent delayed reports

On receiving a IGMPv2/v3 query, based on max_delay set in the header a timer is started to send out a response after a random time within max_delay. If the system then moves into suspend state, Report is delayed until system wakes up.

Use a alarmtimer instead of using a timer. Alarmtimer will wake the system up from suspend to send out the IGMP report.

Signed-off-by Tejaswi Tanikella <[email protected]>

---
v2: use alarmtimer instead of wakelock.
v3: add patches in the right order.
---
If these changes are fine, I'll share similar patches for MLD and ARP.

---
 include/linux/igmp.h |  7 ++++++-
 net/ipv4/igmp.c      | 27 ++++++++++++++++-----------
 2 files changed, 22 insertions(+), 12 deletions(-)
include/linux/igmp.h +6 -1
index f823185..45852eb 100644
@@ -20,6 +20,9 @@
 #include <linux/in.h>
 #include <linux/refcount.h>
 #include <uapi/linux/igmp.h>
+#ifdef CONFIG_IP_MULTICAST
+#include <linux/alarmtimer.h>
+#endif
 
 static inline struct igmphdr *igmp_hdr(const struct sk_buff *skb)
 {

@@ -83,7 +86,9 @@ struct ip_mc_list {
 		struct ip_mc_list __rcu *next_rcu;
 	};
 	struct ip_mc_list __rcu *next_hash;
-	struct timer_list	timer;
+#ifdef CONFIG_IP_MULTICAST
+	struct alarm		alarm;
+#endif
 	int			users;
 	refcount_t		refcnt;
 	spinlock_t		lock;
net/ipv4/igmp.c +16 -11
index 85b617b..c30b5c4 100644
@@ -199,7 +199,7 @@ static void ip_ma_put(struct ip_mc_list *im)
 static void igmp_stop_timer(struct ip_mc_list *im)
 {
 	spin_lock_bh(&im->lock);
-	if (del_timer(&im->timer))
+	if (alarm_cancel(&im->alarm))
 		refcount_dec(&im->refcnt);
 	im->tm_running = 0;
 	im->reporter = 0;

@@ -210,11 +210,11 @@ static void igmp_stop_timer(struct ip_mc_list *im)
 /* It must be called with locked im->lock */
 static void igmp_start_timer(struct ip_mc_list *im, int max_delay)
 {
-	int tv = prandom_u32() % max_delay;
+	ktime_t expiry = jiffies_to_ktime(prandom_u32() % max_delay + 2);
 
 	im->tm_running = 1;
-	if (!mod_timer(&im->timer, jiffies+tv+2))
-		refcount_inc(&im->refcnt);
+	alarm_start_relative(&im->alarm, expiry);
+	refcount_inc(&im->refcnt);
 }
 
 static void igmp_gq_start_timer(struct in_device *in_dev)

@@ -241,11 +241,14 @@ static void igmp_ifc_start_timer(struct in_device *in_dev, int delay)
 
 static void igmp_mod_timer(struct ip_mc_list *im, int max_delay)
 {
+	ktime_t expiry;
+
 	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);
+	expiry = alarm_expires_remaining(&im->alarm);
+	if (alarm_cancel(&im->alarm)) {
+		if (ktime_to_jiffies(expiry) < max_delay) {
+			alarm_start_relative(&im->alarm, expiry);
 			im->tm_running = 1;
 			spin_unlock_bh(&im->lock);
 			return;

@@ -812,9 +815,9 @@ static void igmp_ifc_event(struct in_device *in_dev)
 }
 
 
-static void igmp_timer_expire(struct timer_list *t)
+enum alarmtimer_restart igmp_timer_expire(struct alarm *alarm, ktime_t now)
 {
-	struct ip_mc_list *im = from_timer(im, t, timer);
+	struct ip_mc_list *im = container_of(alarm, struct ip_mc_list, alarm);
 	struct in_device *in_dev = im->interface;
 
 	spin_lock(&im->lock);

@@ -835,6 +838,8 @@ static void igmp_timer_expire(struct timer_list *t)
 		igmp_send_report(in_dev, im, IGMPV3_HOST_MEMBERSHIP_REPORT);
 
 	ip_ma_put(im);
+
+	return ALARMTIMER_NORESTART;
 }
 
 /* mark EXCLUDE-mode sources */

@@ -1413,7 +1418,7 @@ void ip_mc_inc_group(struct in_device *in_dev, __be32 addr)
 	refcount_set(&im->refcnt, 1);
 	spin_lock_init(&im->lock);
 #ifdef CONFIG_IP_MULTICAST
-	timer_setup(&im->timer, igmp_timer_expire, 0);
+	alarm_init(&im->alarm, ALARM_BOOTTIME, igmp_timer_expire);
 	im->unsolicit_count = net->ipv4.sysctl_igmp_qrv;
 #endif
 

@@ -2811,7 +2816,7 @@ static int igmp_mc_seq_show(struct seq_file *seq, void *v)
 				   state->dev->ifindex, state->dev->name, state->in_dev->mc_count, querier);
 		}
 
-		delta = im->timer.expires - jiffies;
+		delta = ktime_to_jiffies(alarm_expires_remaining(&im->alarm));
 		seq_printf(seq,
 			   "\t\t\t\t%08X %5d %d:%08lX\t\t%d\n",
 			   im->multiaddr, im->users,
Signature · 1 line
1.9.1
build bot
#2 lore raw

Re: [PATCH net v3 2/2] ipv4: igmp: use alarmtimer to prevent delayed reports

Thank you for the patch! Yet something to improve:

Hi Tejaswi,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on net/master]

url: https://github.com/0day-ci/linux/commits/Tejaswi-Tanikella/ktime-helpers-to-convert-between-ktime-and-jiffies/20180611-214916
config: x86_64-randconfig-s4-06200944 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-16) 7.3.0
reproduce:

        # save the attached .config to linux build tree
        make ARCH=x86_64

All errors (new ones prefixed by >>):

In file included from include/linux/timer.h:6:0,

                    from include/linux/workqueue.h:9,
                    from include/linux/srcu.h:34,
                    from include/linux/notifier.h:16,
                    from include/linux/memory_hotplug.h:7,
                    from include/linux/mmzone.h:777,
                    from include/linux/gfp.h:6,
                    from include/linux/umh.h:4,
                    from include/linux/kmod.h:22,
                    from include/linux/module.h:13,
                    from net/ipv4/igmp.c:73:
   net/ipv4/igmp.c: In function 'igmp_mc_seq_show':
>> net/ipv4/igmp.c:2819:28: error: implicit declaration of function 'alarm_expires_remaining'; did you mean 'hrtimer_expires_remaining'? [-Werror=implicit-function-declaration]
      delta = ktime_to_jiffies(alarm_expires_remaining(&im->alarm));
                               ^
   include/linux/ktime.h:100:48: note: in definition of macro 'ktime_to_jiffies'
    #define ktime_to_jiffies(kt)  nsecs_to_jiffies(kt)
                                                   ^~
>> net/ipv4/igmp.c:2819:55: error: 'struct ip_mc_list' has no member named 'alarm'
      delta = ktime_to_jiffies(alarm_expires_remaining(&im->alarm));
                                                          ^
   include/linux/ktime.h:100:48: note: in definition of macro 'ktime_to_jiffies'
    #define ktime_to_jiffies(kt)  nsecs_to_jiffies(kt)
                                                   ^~

cc1: some warnings being treated as errors

vim +2819 net/ipv4/igmp.c

2813
2814 if (rcu_access_pointer(state->in_dev->mc_list) == im) {
2815 seq_printf(seq, "%d\t%-10s: %5d %7s\n",
2816 state->dev->ifindex, state->dev->name, state->in_dev->mc_count, querier);
2817 }
2818

> 2819			delta = ktime_to_jiffies(alarm_expires_remaining(&im->alarm));
  2820			seq_printf(seq,
  2821				   "\t\t\t\t%08X %5d %d:%08lX\t\t%d\n",
  2822				   im->multiaddr, im->users,
  2823				   im->tm_running,
  2824				   im->tm_running ? jiffies_delta_to_clock_t(delta) : 0,
  2825				   im->reporter);

2826 }
2827 return 0;
2828 }
2829

---
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