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From: Eric Dumazet <edumazet@google.com>
To: "David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org, eric.dumazet@gmail.com,
	Eric Dumazet <edumazet@google.com>
Subject: [PATCH v2 net-next 18/19] ipmr: convert mrt_lock to a spinlock
Date: Thu, 23 Jun 2022 04:34:48 +0000	[thread overview]
Message-ID: <20220623043449.1217288-19-edumazet@google.com> (raw)
In-Reply-To: <20220623043449.1217288-1-edumazet@google.com>

mrt_lock is only held in write mode, from process context only.

We can switch to a mere spinlock, and avoid blocking BH.

Also, vif_dev_read() is always called under standard rcu_read_lock().

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv4/ipmr.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 2e39f73fe81a2392e07af83fd933033964e3a730..f095b6c8100bd24262c949390b68865b8b3987c3 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -77,12 +77,11 @@ struct ipmr_result {
  * Note that the changes are semaphored via rtnl_lock.
  */
 
-static DEFINE_RWLOCK(mrt_lock);
+static DEFINE_SPINLOCK(mrt_lock);
 
 static struct net_device *vif_dev_read(const struct vif_device *vif)
 {
-	return rcu_dereference_check(vif->dev,
-				     lockdep_is_held(&mrt_lock));
+	return rcu_dereference(vif->dev);
 }
 
 /* Multicast router control variables */
@@ -664,7 +663,7 @@ static int vif_delete(struct mr_table *mrt, int vifi, int notify,
 	if (!dev)
 		return -EADDRNOTAVAIL;
 
-	write_lock_bh(&mrt_lock);
+	spin_lock(&mrt_lock);
 	call_ipmr_vif_entry_notifiers(net, FIB_EVENT_VIF_DEL, v, dev,
 				      vifi, mrt->id);
 	RCU_INIT_POINTER(v->dev, NULL);
@@ -683,7 +682,7 @@ static int vif_delete(struct mr_table *mrt, int vifi, int notify,
 		WRITE_ONCE(mrt->maxvif, tmp + 1);
 	}
 
-	write_unlock_bh(&mrt_lock);
+	spin_unlock(&mrt_lock);
 
 	dev_set_allmulti(dev, -1);
 
@@ -785,7 +784,7 @@ static void ipmr_expire_process(struct timer_list *t)
 	spin_unlock(&mfc_unres_lock);
 }
 
-/* Fill oifs list. It is called under write locked mrt_lock. */
+/* Fill oifs list. It is called under locked mrt_lock. */
 static void ipmr_update_thresholds(struct mr_table *mrt, struct mr_mfc *cache,
 				   unsigned char *ttls)
 {
@@ -897,7 +896,7 @@ static int vif_add(struct net *net, struct mr_table *mrt,
 	v->remote = vifc->vifc_rmt_addr.s_addr;
 
 	/* And finish update writing critical data */
-	write_lock_bh(&mrt_lock);
+	spin_lock(&mrt_lock);
 	rcu_assign_pointer(v->dev, dev);
 	netdev_tracker_alloc(dev, &v->dev_tracker, GFP_ATOMIC);
 	if (v->flags & VIFF_REGISTER) {
@@ -906,7 +905,7 @@ static int vif_add(struct net *net, struct mr_table *mrt,
 	}
 	if (vifi+1 > mrt->maxvif)
 		WRITE_ONCE(mrt->maxvif, vifi + 1);
-	write_unlock_bh(&mrt_lock);
+	spin_unlock(&mrt_lock);
 	call_ipmr_vif_entry_notifiers(net, FIB_EVENT_VIF_ADD, v, dev,
 				      vifi, mrt->id);
 	return 0;
@@ -1211,12 +1210,12 @@ static int ipmr_mfc_add(struct net *net, struct mr_table *mrt,
 				   mfc->mfcc_mcastgrp.s_addr, parent);
 	rcu_read_unlock();
 	if (c) {
-		write_lock_bh(&mrt_lock);
+		spin_lock(&mrt_lock);
 		c->_c.mfc_parent = mfc->mfcc_parent;
 		ipmr_update_thresholds(mrt, &c->_c, mfc->mfcc_ttls);
 		if (!mrtsock)
 			c->_c.mfc_flags |= MFC_STATIC;
-		write_unlock_bh(&mrt_lock);
+		spin_unlock(&mrt_lock);
 		call_ipmr_mfc_entry_notifiers(net, FIB_EVENT_ENTRY_REPLACE, c,
 					      mrt->id);
 		mroute_netlink_event(mrt, c, RTM_NEWROUTE);
-- 
2.37.0.rc0.104.g0611611a94-goog


  parent reply	other threads:[~2022-06-23  4:41 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-23  4:34 [PATCH v2 net-next 00/19] ipmr: get rid of rwlocks Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 01/19] ip6mr: do not get a device reference in pim6_rcv() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 02/19] ipmr: add rcu protection over (struct vif_device)->dev Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 03/19] ipmr: change igmpmsg_netlink_event() prototype Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 04/19] ipmr: ipmr_cache_report() changes Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 05/19] ipmr: do not acquire mrt_lock in __pim_rcv() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 06/19] ipmr: do not acquire mrt_lock in ioctl(SIOCGETVIFCNT) Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 07/19] ipmr: do not acquire mrt_lock before calling ipmr_cache_unresolved() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 08/19] ipmr: do not acquire mrt_lock while calling ip_mr_forward() Eric Dumazet
2022-07-22 19:34   ` Vladimir Oltean
2022-07-22 20:37     ` Eric Dumazet
2022-07-22 21:10       ` Vladimir Oltean
2022-07-22 21:15         ` Vladimir Oltean
2022-06-23  4:34 ` [PATCH v2 net-next 09/19] ipmr: do not acquire mrt_lock in ipmr_get_route() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 10/19] ip6mr: ip6mr_cache_report() changes Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 11/19] ip6mr: do not acquire mrt_lock in pim6_rcv() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 12/19] ip6mr: do not acquire mrt_lock in ioctl(SIOCGETMIFCNT_IN6) Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 13/19] ip6mr: do not acquire mrt_lock before calling ip6mr_cache_unresolved Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 14/19] ip6mr: do not acquire mrt_lock while calling ip6_mr_forward() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 15/19] ip6mr: switch ip6mr_get_route() to rcu_read_lock() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 16/19] ipmr: adopt rcu_read_lock() in mr_dump() Eric Dumazet
2022-06-23  4:34 ` [PATCH v2 net-next 17/19] ipmr: convert /proc handlers to rcu_read_lock() Eric Dumazet
2022-06-23  4:34 ` Eric Dumazet [this message]
2022-06-23  4:34 ` [PATCH v2 net-next 19/19] ip6mr: convert mrt_lock to a spinlock Eric Dumazet
2022-06-24 10:50 ` [PATCH v2 net-next 00/19] ipmr: get rid of rwlocks patchwork-bot+netdevbpf

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