[ANNOUNCE] 4.6.7-rt12v4.6.7-rt12-patches

Dear RT folks!

I'm pleased to announce the v4.6.7-rt12 patch set.

Changes since v4.6.7-rt11:

  - The update to v4.6.7-rt11 introduced a performance regression
    especially visible when compiling a kernel on /dev/shm. It is fixed
    by invoking less often the "chill" function. Reported by Joakim
    Hernberg.

  - We had a fix in v3.12.8-rt11 for ip_send_unicast_reply() which I
    dropped in v3.18.8 based -RT due code change and I assumed the need
    for extra serialization is no longer required. As it turns out it is
    still required :)

  - While looking around a similar serialisation might be required in
    icmp_sk(). No crash has been observed, this is just precaution.

Known issues
	- CPU hotplug got a little better but can deadlock.

The delta patch against 4.6.7-rt11 is appended below and can be found here:

     https://cdn.kernel.org/pub/linux/kernel/projects/rt/4.6/incr/patch-4.6.7-rt11-rt12.patch.xz

You can get this release via the git tree at:

    git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v4.6.7-rt12

The RT patch against 4.6.5 can be found here:

    https://cdn.kernel.org/pub/linux/kernel/projects/rt/4.6/patch-4.6.7-rt12.patch.xz

The split quilt queue is available at:

    https://cdn.kernel.org/pub/linux/kernel/projects/rt/4.6/patches-4.6.7-rt12.tar.xz

Sebastian

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

1 files changed, 87 insertions, 0 deletions

diff --git a/patches/net-add-back-the-missing-serialization-in-ip_send_un.patch b/patches/net-add-back-the-missing-serialization-in-ip_send_un.patch
new file mode 100644
index 000000000000..2c83f004fc3b
--- /dev/null
+++ b/patches/net-add-back-the-missing-serialization-in-ip_send_un.patch
@@ -0,0 +1,87 @@
+From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Date: Wed, 31 Aug 2016 17:21:56 +0200
+Subject: [PATCH] net: add back the missing serialization in
+ ip_send_unicast_reply()
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Some time ago Sami Pietikäinen reported a crash on -RT in
+ip_send_unicast_reply() which was later fixed by Nicholas Mc Guire
+(v3.12.8-rt11). Later (v3.18.8) the code was reworked and I dropped the
+patch. As it turns out it was mistake.
+I have reports that the same crash is possible with a similar backtrace.
+It seems that vanilla protects access to this_cpu_ptr() via
+local_bh_disable(). This does not work the on -RT since we can have
+NET_RX and NET_TX running in parallel on the same CPU.
+This is brings back the old locks.
+
+|Unable to handle kernel NULL pointer dereference at virtual address 00000010
+|PC is at __ip_make_skb+0x198/0x3e8
+|[<c04e39d8>] (__ip_make_skb) from [<c04e3ca8>] (ip_push_pending_frames+0x20/0x40)
+|[<c04e3ca8>] (ip_push_pending_frames) from [<c04e3ff0>] (ip_send_unicast_reply+0x210/0x22c)
+|[<c04e3ff0>] (ip_send_unicast_reply) from [<c04fbb54>] (tcp_v4_send_reset+0x190/0x1c0)
+|[<c04fbb54>] (tcp_v4_send_reset) from [<c04fcc1c>] (tcp_v4_do_rcv+0x22c/0x288)
+|[<c04fcc1c>] (tcp_v4_do_rcv) from [<c0474364>] (release_sock+0xb4/0x150)
+|[<c0474364>] (release_sock) from [<c04ed904>] (tcp_close+0x240/0x454)
+|[<c04ed904>] (tcp_close) from [<c0511408>] (inet_release+0x74/0x7c)
+|[<c0511408>] (inet_release) from [<c0470728>] (sock_release+0x30/0xb0)
+|[<c0470728>] (sock_release) from [<c0470abc>] (sock_close+0x1c/0x24)
+|[<c0470abc>] (sock_close) from [<c0115ec4>] (__fput+0xe8/0x20c)
+|[<c0115ec4>] (__fput) from [<c0116050>] (____fput+0x18/0x1c)
+|[<c0116050>] (____fput) from [<c0058138>] (task_work_run+0xa4/0xb8)
+|[<c0058138>] (task_work_run) from [<c0011478>] (do_work_pending+0xd0/0xe4)
+|[<c0011478>] (do_work_pending) from [<c000e740>] (work_pending+0xc/0x20)
+|Code: e3530001 8a000001 e3a00040 ea000011 (e5973010)
+
+Cc: stable-rt@vger.kernel.org
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+---
+ net/ipv4/tcp_ipv4.c |    7 +++++++
+ 1 file changed, 7 insertions(+)
+
+--- a/net/ipv4/tcp_ipv4.c
++++ b/net/ipv4/tcp_ipv4.c
+@@ -62,6 +62,7 @@
+ #include <linux/init.h>
+ #include <linux/times.h>
+ #include <linux/slab.h>
++#include <linux/locallock.h>
+ 
+ #include <net/net_namespace.h>
+ #include <net/icmp.h>
+@@ -565,6 +566,7 @@ void tcp_v4_send_check(struct sock *sk,
+ }
+ EXPORT_SYMBOL(tcp_v4_send_check);
+ 
++static DEFINE_LOCAL_IRQ_LOCK(tcp_sk_lock);
+ /*
+  *	This routine will send an RST to the other tcp.
+  *
+@@ -689,10 +691,13 @@ static void tcp_v4_send_reset(const stru
+ 		     offsetof(struct inet_timewait_sock, tw_bound_dev_if));
+ 
+ 	arg.tos = ip_hdr(skb)->tos;
++
++	local_lock(tcp_sk_lock);
+ 	ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk),
+ 			      skb, &TCP_SKB_CB(skb)->header.h4.opt,
+ 			      ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
+ 			      &arg, arg.iov[0].iov_len);
++	local_unlock(tcp_sk_lock);
+ 
+ 	TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
+ 	TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
+@@ -774,10 +779,12 @@ static void tcp_v4_send_ack(struct net *
+ 	if (oif)
+ 		arg.bound_dev_if = oif;
+ 	arg.tos = tos;
++	local_lock(tcp_sk_lock);
+ 	ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk),
+ 			      skb, &TCP_SKB_CB(skb)->header.h4.opt,
+ 			      ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
+ 			      &arg, arg.iov[0].iov_len);
++	local_unlock(tcp_sk_lock);
+ 
+ 	TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
+ }