Currently kdb's ftdump command will livelock by constantly printk'ing the empty string at KERN_EMERG level if it run when the ftrace system is not in use. This occurs because trace_empty() never returns false when the ring buffers are left at the start of a non-consuming read [launched by ring_buffer_read_start()].
This patch changes the loop exit condition to use the result of trace_find_next_entry_inc(). Effectively this switches the non-consuming kdb dumper to follow the approach of the non-consuming userspace interface [s_next()] rather than the consuming ftrace_dump(). Signed-off-by: Daniel Thompson <[email protected]> Cc: Jason Wessel <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Ingo Molnar <[email protected]> --- kernel/trace/trace_kdb.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c index 8faa7ce..b0b1c44 100644 --- a/kernel/trace/trace_kdb.c +++ b/kernel/trace/trace_kdb.c @@ -59,19 +59,19 @@ static void ftrace_dump_buf(int skip_lines, long cpu_file) ring_buffer_read_start(iter.buffer_iter[cpu_file]); tracing_iter_reset(&iter, cpu_file); } - if (!trace_empty(&iter)) - trace_find_next_entry_inc(&iter); - while (!trace_empty(&iter)) { + + while (trace_find_next_entry_inc(&iter)) { if (!cnt) kdb_printf("---------------------------------\n"); cnt++; - if (trace_find_next_entry_inc(&iter) != NULL && !skip_lines) + if (!skip_lines) { print_trace_line(&iter); - if (!skip_lines) trace_printk_seq(&iter.seq); - else + } else { skip_lines--; + } + if (KDB_FLAG(CMD_INTERRUPT)) goto out; } -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
