[ovs-dev] [PATCH 02/13] compat: Detect and use inet_frag_queue->list_evictor.

[Joe Stringer]

Kernels 3.17 to 4.2 have a work queue to evict old fragments, but do not
track these fragments in an eviction list. On these kernels, we detect
the absence of the list_evictor and provide one. This commit fixes the
reliance on kernel versions in the case that this functionality is
backported.

Signed-off-by: Joe Stringer <joe at ovn.org>
---
 acinclude.m4                                  |  2 ++
 datapath/linux/compat/include/net/inet_frag.h |  2 ++
 datapath/linux/compat/inet_fragment.c         | 16 ++++++++--------
 datapath/linux/compat/ip_fragment.c           |  2 +-
 4 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/acinclude.m4 b/acinclude.m4
index b78244d6bf4f..1da00288d67f 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -354,6 +354,8 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
                   [OVS_DEFINE([HAVE_INET_FRAGS_CONST])])
   OVS_GREP_IFELSE([$KSRC/include/net/inet_frag.h], [last_in],
                   [OVS_DEFINE([HAVE_INET_FRAGS_LAST_IN])])
+  OVS_FIND_FIELD_IFELSE([$KSRC/include/net/inet_frag.h], [inet_frag_queue],
+                        [list_evictor])
 
   OVS_GREP_IFELSE([$KSRC/include/net/dst_metadata.h], [metadata_dst])
 
diff --git a/datapath/linux/compat/include/net/inet_frag.h b/datapath/linux/compat/include/net/inet_frag.h
index 0c0c07619126..147435af6ae7 100644
--- a/datapath/linux/compat/include/net/inet_frag.h
+++ b/datapath/linux/compat/include/net/inet_frag.h
@@ -22,6 +22,7 @@
 #define qp_flags(qp) (qp->q.flags)
 #endif
 
+#ifndef HAVE_INET_FRAG_QUEUE_WITH_LIST_EVICTOR
 /**
  * struct ovs_inet_frag_queue - fragment queue
  *
@@ -44,6 +45,7 @@ static inline bool rpl_inet_frag_evicting(struct inet_frag_queue *q)
 #endif
 }
 #define inet_frag_evicting rpl_inet_frag_evicting
+#endif /* HAVE_INET_FRAG_QUEUE_WITH_LIST_EVICTOR */
 
 static unsigned int rpl_frag_percpu_counter_batch = 130000;
 #define frag_percpu_counter_batch rpl_frag_percpu_counter_batch
diff --git a/datapath/linux/compat/inet_fragment.c b/datapath/linux/compat/inet_fragment.c
index 323226880f3d..1e335bc68c55 100644
--- a/datapath/linux/compat/inet_fragment.c
+++ b/datapath/linux/compat/inet_fragment.c
@@ -130,7 +130,7 @@ static bool inet_fragq_should_evict(const struct inet_frag_queue *q)
 static unsigned int
 inet_evict_bucket(struct inet_frags *f, struct inet_frag_bucket *hb)
 {
-#if LINUX_VERSION_CODE < KERNEL_VERSION(4,2,0)
+#ifndef HAVE_INET_FRAG_QUEUE_WITH_LIST_EVICTOR
 	struct ovs_inet_frag_queue *ofq;
 #endif
 	struct inet_frag_queue *fq;
@@ -147,23 +147,23 @@ inet_evict_bucket(struct inet_frags *f, struct inet_frag_bucket *hb)
 		if (!del_timer(&fq->timer))
 			continue;
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(4,2,0)
+#ifdef HAVE_INET_FRAG_QUEUE_WITH_LIST_EVICTOR
+		hlist_add_head(&fq->list_evictor, &expired);
+#else
 		ofq = (struct ovs_inet_frag_queue *)fq;
 		hlist_add_head(&ofq->list_evictor, &expired);
-#else
-		hlist_add_head(&fq->list_evictor, &expired);
 #endif
 		++evicted;
 	}
 
 	spin_unlock(&hb->chain_lock);
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(4,2,0)
-	hlist_for_each_entry_safe(ofq, n, &expired, list_evictor)
-		f->frag_expire((unsigned long) &ofq->fq);
-#else
+#ifdef HAVE_INET_FRAG_QUEUE_WITH_LIST_EVICTOR
 	hlist_for_each_entry_safe(fq, n, &expired, list_evictor)
 		f->frag_expire((unsigned long) fq);
+#else
+	hlist_for_each_entry_safe(ofq, n, &expired, list_evictor)
+		f->frag_expire((unsigned long) &ofq->fq);
 #endif
 
 	return evicted;
diff --git a/datapath/linux/compat/ip_fragment.c b/datapath/linux/compat/ip_fragment.c
index 418134928114..b683aaffedde 100644
--- a/datapath/linux/compat/ip_fragment.c
+++ b/datapath/linux/compat/ip_fragment.c
@@ -78,7 +78,7 @@ struct ipfrag_skb_cb
 struct ipq {
 	union {
 		struct inet_frag_queue q;
-#if LINUX_VERSION_CODE < KERNEL_VERSION(4,2,0)
+#ifndef HAVE_INET_FRAG_QUEUE_WITH_LIST_EVICTOR
 		struct ovs_inet_frag_queue oq;
 #endif
 	};
-- 
2.1.4