tracing: move tgid out of generic entry and into userstack

The userstack trace required the recording of the tgid entry.
Unfortunately, it was added to the generic entry where it wasted
4 bytes of every entry and was only used by one entry.

This patch moves it out of the generic field and moves it into the
only user (userstack_entry).

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

5 files changed, 4 insertions, 7 deletions

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 23f7179bf74e..06c795b536c2 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -34,7 +34,6 @@ struct trace_entry {
         unsigned char           flags;
         unsigned char           preempt_count;
         int                     pid;
-        int                     tgid;
 };
 
 #define FTRACE_MAX_EVENT                                                \
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5c75deeefe30..1a37da2e8534 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -886,7 +886,6 @@ tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
 
         entry->preempt_count            = pc & 0xff;
         entry->pid                      = (tsk) ? tsk->pid : 0;
-        entry->tgid                     = (tsk) ? tsk->tgid : 0;
         entry->flags =
 #ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
                 (irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
@@ -1068,6 +1067,7 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
                 return;
         entry   = ring_buffer_event_data(event);
 
+        entry->tgid             = current->tgid;
         memset(&entry->caller, 0, sizeof(entry->caller));
 
         trace.nr_entries        = 0;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index acaa68060ebc..b69697b4b846 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -101,6 +101,7 @@ struct stack_entry {
 
 struct userstack_entry {
         struct trace_entry      ent;
+        unsigned int            tgid;
         unsigned long           caller[FTRACE_STACK_ENTRIES];
 };
 
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 78b1ed230177..28d92027a93c 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -86,7 +86,6 @@ int trace_define_common_fields(struct ftrace_event_call *call)
         __common_field(unsigned char, flags);
         __common_field(unsigned char, preempt_count);
         __common_field(int, pid);
-        __common_field(int, tgid);
 
         return ret;
 }
@@ -572,13 +571,11 @@ static int trace_write_header(struct trace_seq *s)
                                 "\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
                                 "\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
                                 "\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
-                                "\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
                                 "\n",
                                 FIELD(unsigned short, type),
                                 FIELD(unsigned char, flags),
                                 FIELD(unsigned char, preempt_count),
-                                FIELD(int, pid),
-                                FIELD(int, tgid));
+                                FIELD(int, pid));
 }
 
 static ssize_t
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index e0c2545622e8..be34a6aa7e4d 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -407,7 +407,7 @@ seq_print_userip_objs(const struct userstack_entry *entry, struct trace_seq *s,
                  * since individual threads might have already quit!
                  */
                 rcu_read_lock();
-                task = find_task_by_vpid(entry->ent.tgid);
+                task = find_task_by_vpid(entry->tgid);
                 if (task)
                         mm = get_task_mm(task);
                 rcu_read_unlock();