tracing: Buffer the output of seq_file in case of filled buffer

[pandora-kernel.git] / kernel / trace / trace.c

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dc937e1..484114d 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1516,6 +1516,8 @@ static void *s_next(struct seq_file *m, void *v, loff_t *pos)
        int i = (int)*pos;
        void *ent;
 
+       WARN_ON_ONCE(iter->leftover);
+
        (*pos)++;
 
        /* can't go backwards */
@@ -1614,8 +1616,16 @@ static void *s_start(struct seq_file *m, loff_t *pos)
                        ;
 
        } else {
-               l = *pos - 1;
-               p = s_next(m, p, &l);
+               /*
+                * If we overflowed the seq_file before, then we want
+                * to just reuse the trace_seq buffer again.
+                */
+               if (iter->leftover)
+                       p = iter;
+               else {
+                       l = *pos - 1;
+                       p = s_next(m, p, &l);
+               }
        }
 
        trace_event_read_lock();
@@ -1923,6 +1933,7 @@ static enum print_line_t print_trace_line(struct trace_iterator *iter)
 static int s_show(struct seq_file *m, void *v)
 {
        struct trace_iterator *iter = v;
+       int ret;
 
        if (iter->ent == NULL) {
                if (iter->tr) {
@@ -1942,9 +1953,27 @@ static int s_show(struct seq_file *m, void *v)
                        if (!(trace_flags & TRACE_ITER_VERBOSE))
                                print_func_help_header(m);
                }
+       } else if (iter->leftover) {
+               /*
+                * If we filled the seq_file buffer earlier, we
+                * want to just show it now.
+                */
+               ret = trace_print_seq(m, &iter->seq);
+
+               /* ret should this time be zero, but you never know */
+               iter->leftover = ret;
+
        } else {
                print_trace_line(iter);
-               trace_print_seq(m, &iter->seq);
+               ret = trace_print_seq(m, &iter->seq);
+               /*
+                * If we overflow the seq_file buffer, then it will
+                * ask us for this data again at start up.
+                * Use that instead.
+                *  ret is 0 if seq_file write succeeded.
+                *        -1 otherwise.
+                */
+               iter->leftover = ret;
        }
 
        return 0;