[5.9,44/46] tracing: Remove WARN_ON in start_thread()

Message ID	20201206111558.584406523@linuxfoundation.org
State	Superseded
Headers	show Return-Path: <stable-owner@kernel.org> From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, stable@vger.kernel.org, Ingo Molnar <mingo@redhat.com>, Vasily Averin <vvs@virtuozzo.com>, "Steven Rostedt (VMware)" <rostedt@goodmis.org> Subject: [PATCH 5.9 44/46] tracing: Remove WARN_ON in start_thread() Date: Sun, 6 Dec 2020 12:17:52 +0100 Message-Id: <20201206111558.584406523@linuxfoundation.org> In-Reply-To: <20201206111556.455533723@linuxfoundation.org> References: <20201206111556.455533723@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	None \| expand [5.9,02/46] devlink: Make sure devlink instance and port are in same net namespace [5.9,03/46] ipv6: addrlabel: fix possible memory leak in ip6addrlbl_net_init [5.9,04/46] net/af_iucv: set correct sk_protocol for child sockets [5.9,05/46] net: openvswitch: fix TTL decrement action netlink message format [5.9,06/46] net/tls: missing received data after fast remote close [5.9,07/46] net/tls: Protect from calling tls_dev_del for TLS RX twice [5.9,08/46] rose: Fix Null pointer dereference in rose_send_frame() [5.9,09/46] sock: set sk_err to ee_errno on dequeue from errq [5.9,10/46] tcp: Set INET_ECN_xmit configuration in tcp_reinit_congestion_control [5.9,11/46] tun: honor IOCB_NOWAIT flag [5.9,12/46] usbnet: ipheth: fix connectivity with iOS 14 [5.9,13/46] vsock/virtio: discard packets only when socket is really closed [5.9,14/46] mptcp: fix NULL ptr dereference on bad MPJ [5.9,15/46] net/packet: fix packet receive on L3 devices without visible hard header [5.9,16/46] netfilter: bridge: reset skb->pkt_type after NF_INET_POST_ROUTING traversal [5.9,17/46] ipv4: Fix tos mask in inet_rtm_getroute() [5.9,18/46] dt-bindings: net: correct interrupt flags in examples [5.9,19/46] chelsio/chtls: fix panic during unload reload chtls [5.9,20/46] ibmvnic: Ensure that SCRQ entry reads are correctly ordered [5.9,21/46] ibmvnic: Fix TX completion error handling [5.9,22/46] tipc: fix incompatible mtu of transmission [5.9,24/46] geneve: pull IP header before ECN decapsulation [5.9,25/46] net: ip6_gre: set dev->hard_header_len when using header_ops [5.9,26/46] dpaa_eth: copy timestamp fields to new skb in A-050385 workaround [5.9,27/46] net/x25: prevent a couple of overflows [5.9,28/46] cxgb3: fix error return code in t3_sge_alloc_qset() [5.9,29/46] net: pasemi: fix error return code in pasemi_mac_open() [5.9,30/46] vxlan: fix error return code in __vxlan_dev_create() [5.9,31/46] chelsio/chtls: fix a double free in chtls_setkey() [5.9,32/46] net: mvpp2: Fix error return code in mvpp2_open() [5.9,33/46] net: skbuff: ensure LSE is pullable before decrementing the MPLS ttl [5.9,34/46] net: openvswitch: ensure LSE is pullable before reading it [5.9,35/46] net/sched: act_mpls: ensure LSE is pullable before reading it [5.9,36/46] net/mlx5: DR, Proper handling of unsupported Connect-X6DX SW steering [5.9,37/46] net/mlx5: Fix wrong address reclaim when command interface is down [5.9,38/46] net: mlx5e: fix fs_tcp.c build when IPV6 is not enabled [5.9,39/46] ALSA: usb-audio: US16x08: fix value count for level meters [5.9,40/46] Input: xpad - support Ardwiino Controllers [5.9,41/46] Input: i8042 - add ByteSpeed touchpad to noloop table [5.9,42/46] Input: atmel_mxt_ts - fix lost interrupts [5.9,43/46] tracing: Fix alignment of static buffer [5.9,44/46] tracing: Remove WARN_ON in start_thread() [5.9,45/46] uapi: fix statx attribute value overlap for DAX & MOUNT_ROOT [5.9,46/46] drm/i915/gt: Fixup tgl mocs for PTE tracking

Message ID

20201206111558.584406523@linuxfoundation.org

State

Superseded

Headers

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
	Vasily Averin <vvs@virtuozzo.com>,
	"Steven Rostedt (VMware)" <rostedt@goodmis.org>
Subject: [PATCH 5.9 44/46] tracing: Remove WARN_ON in start_thread()
Date: Sun,  6 Dec 2020 12:17:52 +0100
Message-Id: <20201206111558.584406523@linuxfoundation.org>
In-Reply-To: <20201206111556.455533723@linuxfoundation.org>
References: <20201206111556.455533723@linuxfoundation.org>
User-Agent: quilt/0.66
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

Series

None | expand

Commit Message

Greg KH Dec. 6, 2020, 11:17 a.m. UTC

From: Vasily Averin <vvs@virtuozzo.com>

commit 310e3a4b5a4fc718a72201c1e4cf5c64ac6f5442 upstream.

This patch reverts commit 978defee11a5 ("tracing: Do a WARN_ON()
 if start_thread() in hwlat is called when thread exists")

.start hook can be legally called several times if according
tracer is stopped

screen window 1
[root@localhost ~]# echo 1 > /sys/kernel/tracing/events/kmem/kfree/enable
[root@localhost ~]# echo 1 > /sys/kernel/tracing/options/pause-on-trace
[root@localhost ~]# less -F /sys/kernel/tracing/trace

screen window 2
[root@localhost ~]# cat /sys/kernel/debug/tracing/tracing_on
0
[root@localhost ~]# echo hwlat >  /sys/kernel/debug/tracing/current_tracer
[root@localhost ~]# echo 1 > /sys/kernel/debug/tracing/tracing_on
[root@localhost ~]# cat /sys/kernel/debug/tracing/tracing_on
0
[root@localhost ~]# echo 2 > /sys/kernel/debug/tracing/tracing_on

triggers warning in dmesg:
WARNING: CPU: 3 PID: 1403 at kernel/trace/trace_hwlat.c:371 hwlat_tracer_start+0xc9/0xd0

Link: https://lkml.kernel.org/r/bd4d3e70-400d-9c82-7b73-a2d695e86b58@virtuozzo.com

Cc: Ingo Molnar <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 978defee11a5 ("tracing: Do a WARN_ON() if start_thread() in hwlat is called when thread exists")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/trace/trace_hwlat.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -368,7 +368,7 @@  static int start_kthread(struct trace_ar
 	struct task_struct *kthread;
 	int next_cpu;
 
-	if (WARN_ON(hwlat_kthread))
+	if (hwlat_kthread)
 		return 0;
 
 	/* Just pick the first CPU on first iteration */

[5.9,44/46] tracing: Remove WARN_ON in start_thread()

Commit Message

Patch