Refactor libinterfork and add support for clone() interception
[ust.git] / libust / tracectl.c
index e28b3159d73c1408b58b072850f2bb89a45d59eb..5e59ca7bc0e8f5cf3ffee07cd6b25e06b3a98a3b 100644 (file)
 #include <urcu-bp.h>
 
 #include <ust/marker.h>
+#include <ust/tracectl.h>
 #include "tracer.h"
 #include "usterr.h"
 #include "ustcomm.h"
-#include "relay.h" /* FIXME: remove */
+#include "buffers.h" /* FIXME: remove */
 #include "marker-control.h"
 
 //#define USE_CLONE
@@ -87,9 +88,8 @@ struct blocked_consumer {
        struct ustcomm_server server;
        struct ustcomm_source src;
 
-       /* args to ltt_do_get_subbuf */
-       struct rchan_buf *rbuf;
-       struct ltt_channel_buf_struct *lttbuf;
+       /* args to ust_buffers_do_get_subbuf */
+       struct ust_buffer *buf;
 
        struct list_head list;
 };
@@ -250,13 +250,13 @@ void process_blocked_consumers(void)
                                continue;
                        }
 
-                       result = ltt_do_get_subbuf(bc->rbuf, bc->lttbuf, &consumed_old);
+                       result = ust_buffers_do_get_subbuf(bc->buf, &consumed_old);
                        if(result == -EAGAIN) {
                                WARN("missed buffer?");
                                continue;
                        }
                        else if(result < 0) {
-                               DBG("ltt_do_get_subbuf: error: %s", strerror(-result));
+                               DBG("ust_buffers_do_get_subbuf: error: %s", strerror(-result));
                        }
                        asprintf(&reply, "%s %ld", "OK", consumed_old);
                        result = ustcomm_send_reply(&bc->server, reply, &bc->src);
@@ -371,6 +371,29 @@ void *listener_main(void *p)
                                return (void *)1;
                        }
                }
+               else if(!strcmp(recvbuf, "trace_create")) {
+                       DBG("trace create");
+
+                       result = ltt_trace_setup(trace_name);
+                       if(result < 0) {
+                               ERR("ltt_trace_setup failed");
+                               return (void *)1;
+                       }
+
+                       result = ltt_trace_set_type(trace_name, trace_type);
+                       if(result < 0) {
+                               ERR("ltt_trace_set_type failed");
+                               return (void *)1;
+                       }
+
+                       result = ltt_trace_alloc(trace_name);
+                       if(result < 0) {
+                               ERR("ltt_trace_alloc failed");
+                               return (void *)1;
+                       }
+
+                       inform_consumer_daemon(trace_name);
+               }
                else if(!strcmp(recvbuf, "trace_start")) {
                        DBG("trace start");
 
@@ -423,16 +446,15 @@ void *listener_main(void *p)
                        }
 
                        for(i=0; i<trace->nr_channels; i++) {
-                               struct rchan *rchan = trace->channels[i].trans_channel_data;
-                               struct rchan_buf *rbuf = rchan->buf;
-                               struct ltt_channel_struct *ltt_channel = (struct ltt_channel_struct *)rchan->private_data;
+                               struct ust_channel *channel = &trace->channels[i];
+                               struct ust_buffer *buf = channel->buf;
 
                                if(!strcmp(trace->channels[i].channel_name, channel_name)) {
                                        char *reply;
 
-                                       DBG("the shmid for the requested channel is %d", rbuf->shmid);
-                                       DBG("the shmid for its buffer structure is %d", ltt_channel->buf_shmid);
-                                       asprintf(&reply, "%d %d", rbuf->shmid, ltt_channel->buf_shmid);
+                                       DBG("the shmid for the requested channel is %d", buf->shmid);
+                                       DBG("the shmid for its buffer structure is %d", channel->buf_shmid);
+                                       asprintf(&reply, "%d %d", buf->shmid, channel->buf_shmid);
 
                                        result = ustcomm_send_reply(&ustcomm_app.server, reply, &src);
                                        if(result) {
@@ -472,13 +494,13 @@ void *listener_main(void *p)
                        }
 
                        for(i=0; i<trace->nr_channels; i++) {
-                               struct rchan *rchan = trace->channels[i].trans_channel_data;
+                               struct ust_channel *channel = &trace->channels[i];
 
                                if(!strcmp(trace->channels[i].channel_name, channel_name)) {
                                        char *reply;
 
-                                       DBG("the n_subbufs for the requested channel is %zd", rchan->n_subbufs);
-                                       asprintf(&reply, "%zd", rchan->n_subbufs);
+                                       DBG("the n_subbufs for the requested channel is %d", channel->subbuf_cnt);
+                                       asprintf(&reply, "%d", channel->subbuf_cnt);
 
                                        result = ustcomm_send_reply(&ustcomm_app.server, reply, &src);
                                        if(result) {
@@ -516,13 +538,13 @@ void *listener_main(void *p)
                        }
 
                        for(i=0; i<trace->nr_channels; i++) {
-                               struct rchan *rchan = trace->channels[i].trans_channel_data;
+                               struct ust_channel *channel = &trace->channels[i];
 
                                if(!strcmp(trace->channels[i].channel_name, channel_name)) {
                                        char *reply;
 
-                                       DBG("the subbuf_size for the requested channel is %zd", rchan->subbuf_size);
-                                       asprintf(&reply, "%zd", rchan->subbuf_size);
+                                       DBG("the subbuf_size for the requested channel is %zd", channel->subbuf_size);
+                                       asprintf(&reply, "%zd", channel->subbuf_size);
 
                                        result = ustcomm_send_reply(&ustcomm_app.server, reply, &src);
                                        if(result) {
@@ -567,11 +589,10 @@ void *listener_main(void *p)
                        }
 
                        for(i=0; i<trace->nr_channels; i++) {
-                               struct rchan *rchan = trace->channels[i].trans_channel_data;
+                               struct ust_channel *channel = &trace->channels[i];
 
                                if(!strcmp(trace->channels[i].channel_name, channel_name)) {
-                                       struct rchan_buf *rbuf = rchan->buf;
-                                       struct ltt_channel_buf_struct *lttbuf = trace->channels[i].buf;
+                                       struct ust_buffer *buf = channel->buf;
                                        struct blocked_consumer *bc;
 
                                        bc = (struct blocked_consumer *) malloc(sizeof(struct blocked_consumer));
@@ -580,9 +601,8 @@ void *listener_main(void *p)
                                                goto next_cmd;
                                        }
                                        bc->fd_consumer = src.fd;
-                                       bc->fd_producer = lttbuf->data_ready_fd_read;
-                                       bc->rbuf = rbuf;
-                                       bc->lttbuf = lttbuf;
+                                       bc->fd_producer = buf->data_ready_fd_read;
+                                       bc->buf = buf;
                                        bc->src = src;
                                        bc->server = ustcomm_app.server;
 
@@ -630,21 +650,20 @@ void *listener_main(void *p)
                        }
 
                        for(i=0; i<trace->nr_channels; i++) {
-                               struct rchan *rchan = trace->channels[i].trans_channel_data;
+                               struct ust_channel *channel = &trace->channels[i];
 
                                if(!strcmp(trace->channels[i].channel_name, channel_name)) {
-                                       struct rchan_buf *rbuf = rchan->buf;
-                                       struct ltt_channel_buf_struct *lttbuf = trace->channels[i].buf;
+                                       struct ust_buffer *buf = channel->buf;
                                        char *reply;
                                        long consumed_old=0;
 
-                                       result = ltt_do_put_subbuf(rbuf, lttbuf, consumed_old);
+                                       result = ust_buffers_do_put_subbuf(buf, consumed_old);
                                        if(result < 0) {
-                                               WARN("ltt_do_put_subbuf: error (subbuf=%s)", channel_name);
+                                               WARN("ust_buffers_do_put_subbuf: error (subbuf=%s)", channel_name);
                                                asprintf(&reply, "%s", "ERROR");
                                        }
                                        else {
-                                               DBG("ltt_do_put_subbuf: success (subbuf=%s)", channel_name);
+                                               DBG("ust_buffers_do_put_subbuf: success (subbuf=%s)", channel_name);
                                                asprintf(&reply, "%s", "OK");
                                        }
 
@@ -931,7 +950,24 @@ static void __attribute__((constructor)) init()
                /* Ensure markers are initialized */
                init_markers();
 
-               /* In case. */
+               /* FIXME: When starting early tracing (here), depending on the
+                * order of constructors, it is very well possible some marker
+                * sections are not yet registered. Because of this, some
+                * channels may not be registered. Yet, we are about to ask the
+                * daemon to collect the channels. Channels which are not yet
+                * registered will not be collected.
+                *
+                * Currently, in LTTng, there is no way to add a channel after
+                * trace start. The reason for this is that it induces complex
+                * concurrency issues on the trace structures, which can only
+                * be resolved using RCU. This has not been done yet. As a
+                * workaround, we are forcing the registration of the "ust"
+                * channel here. This is the only channel (apart from metadata)
+                * that can be reliably used in early tracing.
+                *
+                * Non-early tracing does not have this problem and can use
+                * arbitrary channel names.
+                */
                ltt_channels_register("ust");
 
                result = ltt_trace_setup(trace_name);
@@ -1087,9 +1123,13 @@ void ust_potential_exec(void)
  * the new process, anytime a process whose memory is not shared with
  * the parent is created. If this function is not called, the events
  * of the new process will not be collected.
+ *
+ * Signals should be disabled before the fork and reenabled only after
+ * this call in order to guarantee tracing is not started before ust_fork()
+ * sanitizes the new process.
  */
 
-void ust_fork(void)
+static void ust_fork(void)
 {
        struct blocked_consumer *bc;
        struct blocked_consumer *deletable_bc = NULL;
@@ -1125,3 +1165,55 @@ void ust_fork(void)
        inform_consumer_daemon("auto");
 }
 
+void ust_before_fork(ust_fork_info_t *fork_info)
+{
+        /* Disable signals. This is to avoid that the child
+         * intervenes before it is properly setup for tracing. It is
+         * safer to disable all signals, because then we know we are not
+         * breaking anything by restoring the original mask.
+         */
+       sigset_t all_sigs;
+       int result;
+
+        /* FIXME:
+                - only do this if tracing is active
+        */
+
+        /* Disable signals */
+        sigfillset(&all_sigs);
+        result = sigprocmask(SIG_BLOCK, &all_sigs, &fork_info->orig_sigs);
+        if(result == -1) {
+                PERROR("sigprocmask");
+                return;
+        }
+}
+
+/* Don't call this function directly in a traced program */
+static void ust_after_fork_common(ust_fork_info_t *fork_info)
+{
+       int result;
+       sigset_t orig_sigs;
+
+        /* Restore signals */
+        result = sigprocmask(SIG_SETMASK, &fork_info->orig_sigs, NULL);
+        if(result == -1) {
+                PERROR("sigprocmask");
+                return;
+        }
+}
+
+void ust_after_fork_parent(ust_fork_info_t *fork_info)
+{
+       /* Reenable signals */
+       ust_after_fork_common(fork_info);
+}
+
+void ust_after_fork_child(ust_fork_info_t *fork_info)
+{
+       /* First sanitize the child */
+       ust_fork();
+
+       /* Then reenable interrupts */
+       ust_after_fork_common(fork_info);
+}
+
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