lkml.org 
[lkml]   [2011]   [Mar]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 1/2] tracing - trace lost events properly
    Date
    Add proper handling of lost event trace, allowing callers
    to get correct trace buffer info.

    - returning TRACE_TYPE_PARTIAL_LINE, in case we dont fit into
    the trace_seq buffer
    - added WARN_ON to make sure we don't miss incorrect trace_seq
    handling

    wbr,
    jirka


    Signed-off-by: Jiri Olsa <jolsa@redhat.com>
    ---
    kernel/trace/trace.c | 14 +++++++++++---
    1 files changed, 11 insertions(+), 3 deletions(-)

    diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
    index 9541c27..20d84f8 100644
    --- a/kernel/trace/trace.c
    +++ b/kernel/trace/trace.c
    @@ -2013,9 +2013,10 @@ enum print_line_t print_trace_line(struct trace_iterator *iter)
    {
    enum print_line_t ret;

    - if (iter->lost_events)
    - trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
    - iter->cpu, iter->lost_events);
    + if (iter->lost_events &&
    + !trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
    + iter->cpu, iter->lost_events))
    + return TRACE_TYPE_PARTIAL_LINE;

    if (iter->trace && iter->trace->print_line) {
    ret = iter->trace->print_line(iter);
    @@ -3229,6 +3230,13 @@ waitagain:

    if (iter->seq.len >= cnt)
    break;
    +
    + /*
    + * Setting the full flag means we reached the trace_seq buffer
    + * size and we should leave by partial output condition above.
    + * One of the trace_seq_* functions is not used properly.
    + */
    + WARN_ON(iter->seq.full);
    }
    trace_access_unlock(iter->cpu_file);
    trace_event_read_unlock();
    --
    1.7.1


    \
     
     \ /
      Last update: 2011-03-13 00:03    [W:0.021 / U:30.764 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site