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Thu, 16 Jul 2020 08:51:30 +0000 (UTC) Date: Thu, 16 Jul 2020 09:51:27 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Roman Bolshakov Subject: Re: [PATCH 4/4] net/colo: Match is-enabled probe to tracepoint Message-ID: <20200716085127.GB227735@redhat.com> References: <20200716081754.22422-1-r.bolshakov@yadro.com> <20200716081754.22422-5-r.bolshakov@yadro.com> MIME-Version: 1.0 In-Reply-To: <20200716081754.22422-5-r.bolshakov@yadro.com> User-Agent: Mutt/1.14.5 (2020-06-23) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/16 01:59:11 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Li Zhijian , Jason Wang , qemu-devel@nongnu.org, Cameron Esfahani , Zhang Chen , Stefan Hajnoczi , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Adding Stefan to CC as the trace maintainer. On Thu, Jul 16, 2020 at 11:17:54AM +0300, Roman Bolshakov wrote: > Build of QEMU with dtrace fails on macOS: > > LINK x86_64-softmmu/qemu-system-x86_64 > error: probe colo_compare_miscompare doesn't exist > error: Could not register probes > ld: error creating dtrace DOF section for architecture x86_64 > > The reason of the error is explained by Adam Leventhal [1]: > > Note that is-enabled probes don't have the stability magic so I'm not > sure how things would work if only is-enabled probes were used. > > net/colo code uses is-enabled probes to determine if other probes should > be used but colo_compare_miscompare itself is not used explicitly. > Linker doesn't include the symbol and build fails. > > The issue can be resolved if is-enabled probe matches the actual trace > point that is used inside the test. > > 1. http://markmail.org/message/6grq2ygr5nwdwsnb > > Fixes: f4b618360e ("colo-compare: add TCP, UDP, ICMP packet comparison") > Cc: Philippe Mathieu-Daudé > Cc: Cameron Esfahani > Signed-off-by: Roman Bolshakov > --- > net/colo-compare.c | 12 +++++++----- > net/filter-rewriter.c | 8 ++++++-- > net/trace-events | 2 -- > 3 files changed, 13 insertions(+), 9 deletions(-) > > diff --git a/net/colo-compare.c b/net/colo-compare.c > index 398b7546ff..9525ed703b 100644 > --- a/net/colo-compare.c > +++ b/net/colo-compare.c > @@ -327,7 +327,7 @@ static int colo_compare_packet_payload(Packet *ppkt, > uint16_t len) > > { > - if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) { > + if (trace_event_get_state_backends(TRACE_COLO_COMPARE_IP_INFO)) { > char pri_ip_src[20], pri_ip_dst[20], sec_ip_src[20], sec_ip_dst[20]; > > strcpy(pri_ip_src, inet_ntoa(ppkt->ip->ip_src)); > @@ -492,7 +492,7 @@ sec: > g_queue_push_head(&conn->primary_list, ppkt); > g_queue_push_head(&conn->secondary_list, spkt); > > - if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) { > + if (trace_event_get_state_backends(TRACE_COLO_COMPARE_TCP_INFO)) { > qemu_hexdump((char *)ppkt->data, stderr, > "colo-compare ppkt", ppkt->size); > qemu_hexdump((char *)spkt->data, stderr, Not your fault, as this problem is pre-existing, but IMHO this block of code is simply broken by design. It is checking a trace event enablement state, and then not emitting any trace event, but instead dumping info to stderr. This is mis-use of the trace framework, and changing the event name fixes your immediate macOS bug but the code is still flawed. Basically it is using the trace framework as a way to dynamically turn on / off general debugging information. I'm not quite sure what todo to fix it, but I don't think it should be wrapped in any trace_event_get_state_backends() call at all. The simplest immediate option I think is to change it to be a compile time debug // #define DEBUG_COLO_PACKETS and then use #ifdef DEBUG_COLO_PACKETS qemu_hexdump(...) #endif and then leave it upto the maintainer to come up with a more advanced solution if they want to make it runtime configurable again, but not abusing the trace framework. > @@ -533,7 +533,8 @@ static int colo_packet_compare_udp(Packet *spkt, Packet *ppkt) > ppkt->size - offset)) { > trace_colo_compare_udp_miscompare("primary pkt size", ppkt->size); > trace_colo_compare_udp_miscompare("Secondary pkt size", spkt->size); > - if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) { > + if (trace_event_get_state_backends( > + TRACE_COLO_COMPARE_UDP_MISCOMPARE)) { > qemu_hexdump((char *)ppkt->data, stderr, "colo-compare pri pkt", > ppkt->size); > qemu_hexdump((char *)spkt->data, stderr, "colo-compare sec pkt", Same brokenness > @@ -576,7 +577,8 @@ static int colo_packet_compare_icmp(Packet *spkt, Packet *ppkt) > ppkt->size); > trace_colo_compare_icmp_miscompare("Secondary pkt size", > spkt->size); > - if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) { > + if (trace_event_get_state_backends( > + TRACE_COLO_COMPARE_ICMP_MISCOMPARE)) { > qemu_hexdump((char *)ppkt->data, stderr, "colo-compare pri pkt", > ppkt->size); > qemu_hexdump((char *)spkt->data, stderr, "colo-compare sec pkt", Same brokenness > @@ -597,7 +599,7 @@ static int colo_packet_compare_other(Packet *spkt, Packet *ppkt) > uint16_t offset = ppkt->vnet_hdr_len; > > trace_colo_compare_main("compare other"); > - if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) { > + if (trace_event_get_state_backends(TRACE_COLO_COMPARE_IP_INFO)) { > char pri_ip_src[20], pri_ip_dst[20], sec_ip_src[20], sec_ip_dst[20]; > > strcpy(pri_ip_src, inet_ntoa(ppkt->ip->ip_src)); > diff --git a/net/filter-rewriter.c b/net/filter-rewriter.c > index 1aaad101b6..ff04165cc4 100644 > --- a/net/filter-rewriter.c > +++ b/net/filter-rewriter.c > @@ -76,7 +76,9 @@ static int handle_primary_tcp_pkt(RewriterState *rf, > struct tcp_hdr *tcp_pkt; > > tcp_pkt = (struct tcp_hdr *)pkt->transport_header; > - if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_DEBUG)) { > + if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_PKT_INFO) || > + trace_event_get_state_backends( > + TRACE_COLO_FILTER_REWRITER_CONN_OFFSET)) { > trace_colo_filter_rewriter_pkt_info(__func__, > inet_ntoa(pkt->ip->ip_src), inet_ntoa(pkt->ip->ip_dst), > ntohl(tcp_pkt->th_seq), ntohl(tcp_pkt->th_ack), Since there are two separate trace events here, each should be wrapped with its own check. IOW, two completely separate if (...) trace(..); blocks > @@ -180,7 +182,9 @@ static int handle_secondary_tcp_pkt(RewriterState *rf, > > tcp_pkt = (struct tcp_hdr *)pkt->transport_header; > > - if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_DEBUG)) { > + if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_PKT_INFO) || > + trace_event_get_state_backends( > + TRACE_COLO_FILTER_REWRITER_CONN_OFFSET)) { > trace_colo_filter_rewriter_pkt_info(__func__, > inet_ntoa(pkt->ip->ip_src), inet_ntoa(pkt->ip->ip_dst), > ntohl(tcp_pkt->th_seq), ntohl(tcp_pkt->th_ack), Same here. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|