Commit d87aa138 authored by Stefan Hajnoczi's avatar Stefan Hajnoczi
Browse files

trace: add trace_event_get_state_backends() 



Code that checks dstate is unaware of SystemTap and LTTng UST dstate, so
the following trace event will not fire when solely enabled by SystemTap
or LTTng UST:

  if (trace_event_get_state(TRACE_MY_EVENT)) {
      str = g_strdup_printf("Expensive string to generate ...",
                            ...);
      trace_my_event(str);
      g_free(str);
  }

Add trace_event_get_state_backends() to fetch backend dstate.  Those
backends that use QEMU dstate fetch it as part of
generate_h_backend_dstate().

Update existing trace_event_get_state() callers to use
trace_event_get_state_backends() instead.

Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Message-id: 20170731140718.22010-3-stefanha@redhat.com
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 3932ef3f

docs/devel/tracing.txt

+1 −1
Original line number Diff line number Diff line
@@ -353,7 +353,7 @@ guard such computations and avoid its compilation when the event is disabled: 
    }



You can check both if the event has been disabled and is dynamically enabled at

the same time using the 'trace_event_get_state' routine (see header

the same time using the 'trace_event_get_state_backends' routine (see header

"trace/control.h" for more information).



=== "tcg" ===

hw/usb/hcd-ohci.c

+5 −8
Original line number Diff line number Diff line
@@ -936,16 +936,18 @@ static int ohci_service_iso_td(OHCIState *ohci, struct ohci_ed *ed, 
    return 1;

}



#ifdef trace_event_get_state

static void ohci_td_pkt(const char *msg, const uint8_t *buf, size_t len)

{

    bool print16 = !!trace_event_get_state(TRACE_USB_OHCI_TD_PKT_SHORT);

    bool printall = !!trace_event_get_state(TRACE_USB_OHCI_TD_PKT_FULL);

    bool print16;

    bool printall;

    const int width = 16;

    int i;

    char tmp[3 * width + 1];

    char *p = tmp;



    print16 = !!trace_event_get_state_backends(TRACE_USB_OHCI_TD_PKT_SHORT);

    printall = !!trace_event_get_state_backends(TRACE_USB_OHCI_TD_PKT_FULL);



    if (!printall && !print16) {

        return;

    }
@@ -967,11 +969,6 @@ static void ohci_td_pkt(const char *msg, const uint8_t *buf, size_t len) 
        p += sprintf(p, " %.2x", buf[i]);

    }

}

#else

static void ohci_td_pkt(const char *msg, const uint8_t *buf, size_t len)

{

}

#endif



/* Service a transport descriptor.

   Returns nonzero to terminate processing of this endpoint.  */

net/colo-compare.c

+6 −5
Original line number Diff line number Diff line
@@ -188,7 +188,7 @@ static int packet_enqueue(CompareState *s, int mode) 
 */

static int colo_packet_compare_common(Packet *ppkt, Packet *spkt, int offset)

{

    if (trace_event_get_state(TRACE_COLO_COMPARE_MISCOMPARE)) {

    if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) {

        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));
@@ -274,7 +274,8 @@ static int colo_packet_compare_tcp(Packet *spkt, Packet *ppkt) 
        res = -1;

    }



    if (res != 0 && trace_event_get_state(TRACE_COLO_COMPARE_MISCOMPARE)) {

    if (res != 0 &&

        trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) {

        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));
@@ -334,7 +335,7 @@ static int colo_packet_compare_udp(Packet *spkt, Packet *ppkt) 
    if (ret) {

        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(TRACE_COLO_COMPARE_MISCOMPARE)) {

        if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) {

            qemu_hexdump((char *)ppkt->data, stderr, "colo-compare pri pkt",

                         ppkt->size);

            qemu_hexdump((char *)spkt->data, stderr, "colo-compare sec pkt",
@@ -371,7 +372,7 @@ 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(TRACE_COLO_COMPARE_MISCOMPARE)) {

        if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) {

            qemu_hexdump((char *)ppkt->data, stderr, "colo-compare pri pkt",

                         ppkt->size);

            qemu_hexdump((char *)spkt->data, stderr, "colo-compare sec pkt",
@@ -390,7 +391,7 @@ static int colo_packet_compare_icmp(Packet *spkt, Packet *ppkt) 
static int colo_packet_compare_other(Packet *spkt, Packet *ppkt)

{

    trace_colo_compare_main("compare other");

    if (trace_event_get_state(TRACE_COLO_COMPARE_MISCOMPARE)) {

    if (trace_event_get_state_backends(TRACE_COLO_COMPARE_MISCOMPARE)) {

        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));

net/filter-rewriter.c

+2 −2
Original line number Diff line number Diff line
@@ -69,7 +69,7 @@ static int handle_primary_tcp_pkt(NetFilterState *nf, 
    struct tcphdr *tcp_pkt;



    tcp_pkt = (struct tcphdr *)pkt->transport_header;

    if (trace_event_get_state(TRACE_COLO_FILTER_REWRITER_DEBUG)) {

    if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_DEBUG)) {

        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),
@@ -115,7 +115,7 @@ static int handle_secondary_tcp_pkt(NetFilterState *nf, 


    tcp_pkt = (struct tcphdr *)pkt->transport_header;



    if (trace_event_get_state(TRACE_COLO_FILTER_REWRITER_DEBUG)) {

    if (trace_event_get_state_backends(TRACE_COLO_FILTER_REWRITER_DEBUG)) {

        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),

trace/control.h

+17 −1
Original line number Diff line number Diff line
@@ -96,7 +96,7 @@ static const char * trace_event_get_name(TraceEvent *ev); 
 * trace_event_get_state:

 * @id: Event identifier name.

 *

 * Get the tracing state of an event (both static and dynamic).

 * Get the tracing state of an event, both static and the QEMU dynamic state.

 *

 * If the event has the disabled property, the check will have no performance

 * impact.
@@ -104,6 +104,22 @@ static const char * trace_event_get_name(TraceEvent *ev); 
#define trace_event_get_state(id)                       \

    ((id ##_ENABLED) && trace_event_get_state_dynamic_by_id(id))



/**

 * trace_event_get_state_backends:

 * @id: Event identifier name.

 *

 * Get the tracing state of an event, both static and dynamic state from all

 * compiled-in backends.

 *

 * If the event has the disabled property, the check will have no performance

 * impact.

 *

 * Returns: true if at least one backend has the event enabled and the event

 * does not have the disabled property.

 */

#define trace_event_get_state_backends(id)              \

    ((id ##_ENABLED) && id ##_BACKEND_DSTATE())



/**

 * trace_event_get_vcpu_state:

 * @vcpu: Target vCPU.