| Message ID | 20200716081754.22422-5-r.bolshakov@yadro.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add dtrace support on macOS | expand |
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 <philmd@redhat.com> > Cc: Cameron Esfahani <dirty@apple.com> > Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com> > --- > 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
On Thu, Jul 16, 2020 at 09:51:27AM +0100, Daniel P. Berrangé wrote: > 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 <philmd@redhat.com> > > Cc: Cameron Esfahani <dirty@apple.com> > > Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com> > > --- > > 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. > Hi Daniel, It makes sense, compile-time define works better because the trace data doesn't go into a trace point. I'll use that approach in v2. > > @@ -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 > Agreed, I'll do that, thanks! > > @@ -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. > > Best regards, Roman
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, @@ -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", @@ -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", @@ -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), @@ -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), diff --git a/net/trace-events b/net/trace-events index fa49c71533..bfaff7891d 100644 --- a/net/trace-events +++ b/net/trace-events @@ -17,10 +17,8 @@ colo_compare_udp_miscompare(const char *sta, int size) ": %s = %d" colo_compare_icmp_miscompare(const char *sta, int size) ": %s = %d" colo_compare_ip_info(int psize, const char *sta, const char *stb, int ssize, const char *stc, const char *std) "ppkt size = %d, ip_src = %s, ip_dst = %s, spkt size = %d, ip_src = %s, ip_dst = %s" colo_old_packet_check_found(int64_t old_time) "%" PRId64 -colo_compare_miscompare(void) "" colo_compare_tcp_info(const char *pkt, uint32_t seq, uint32_t ack, int hdlen, int pdlen, int offset, int flags) "%s: seq/ack= %u/%u hdlen= %d pdlen= %d offset= %d flags=%d" # filter-rewriter.c -colo_filter_rewriter_debug(void) "" colo_filter_rewriter_pkt_info(const char *func, const char *src, const char *dst, uint32_t seq, uint32_t ack, uint32_t flag) "%s: src/dst: %s/%s p: seq/ack=%u/%u flags=0x%x" colo_filter_rewriter_conn_offset(uint32_t offset) ": offset=%u"
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 <philmd@redhat.com> Cc: Cameron Esfahani <dirty@apple.com> Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com> --- net/colo-compare.c | 12 +++++++----- net/filter-rewriter.c | 8 ++++++-- net/trace-events | 2 -- 3 files changed, 13 insertions(+), 9 deletions(-)