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  1. 17 Mar, 2009 3 commits
    • Steven Rostedt's avatar
      tracing: stop comm recording on tracing off · 6adaad14
      Steven Rostedt authored 
      Impact: fix for losing comms in trace

The command lines of tasks are cached at sched switch to not need
to record them at every trace point.  Disabling the tracing on stops
the recording of traces, but does not stop the caching of command lines.
When the tracing is off the cache may overflow and cause the tracing
to show incorrect tasks matching the PIDs.

This patch disables prevents updates to the comm cache when the ring buffer
is off.
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
      6adaad14
    • Steven Rostedt's avatar
      tracing: protect reader of cmdline output · 4ca53085
      Steven Rostedt authored 
      Impact: fix to one cause of incorrect comm outputs in trace

The spinlock only protected the creation of a comm <=> pid pair.
But it was possible that a reader could look up a pid, and get the
wrong comm because it had no locking.

This also required changing trace_find_cmdline to copy the comm cache
and not just send back a pointer to it.
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
      4ca53085
    • Frederic Weisbecker's avatar
      tracing/ftrace: fix the check on nopped sites · 03303549
      Frederic Weisbecker authored 
      Impact: fix a dynamic tracing failure

Recently, the function and function graph tracers failed to use dynamic
tracing after the following commit:

fa9d13cf
(ftrace: don't try to __ftrace_replace_code on !FTRACE_FL_CONVERTED rec)

The patch is right except a mistake on the check for the FTRACE_FL_CONVERTED
flag. The code patching is aborted in case of successfully nopped sites.
What we want is the opposite: ignore the callsites that haven't been nopped.
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
      03303549
  3. 14 Mar, 2009 1 commit
    • Lai Jiangshan's avatar
      kallsyms, tracing: output more proper symbol name · b478b782
      Lai Jiangshan authored 
      Impact: bugfix, output more reliable symbol lookup result

Debug tools(dump_stack(), ftrace...) are like to print out symbols.
But it is always print out the first aliased symbol.(Aliased symbols
are symbols with the same address), and the first aliased symbol is
sometime not proper.

 # echo function_graph > current_tracer
 # cat trace
......
 1)   1.923 us    |    select_nohz_load_balancer();
 1) + 76.692 us   |  }
 1)               |  default_idle() {
 1)   ==========> |    __irqentry_text_start() {
 1)   0.000 us    |      native_apic_mem_write();
 1)               |      irq_enter() {
 1)   0.000 us    |        idle_cpu();
 1)               |        tick_check_idle() {
 1)   0.000 us    |          tick_check_oneshot_broadcast();
 1)               |          tick_nohz_stop_idle() {
......

It's very embarrassing, it ouputs "__irqentry_text_start()",
actually, it should output "smp_apic_timer_interrupt()".
(these two symbol are the same address, but "__irqentry_text_start"
is deemed to the first aliased symbol by scripts/kallsyms)

This patch puts symbols like "__irqentry_text_start" to the second
aliased symbols. And a more proper symbol name becomes the first.

Aliased symbols mostly come from linker script. The solution is
guessing "is this symbol defined in linker script", the symbols
defined in linker script will not become the first aliased symbol.

And if symbols are found to be equal in this "linker script provided"
criteria, symbols are sorted by the number of prefix underscores.
Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: default avatarSam Ravnborg <sam@ravnborg.org>
Reviewed-by: default avatarPaulo Marques <pmarques@grupopie.com>
LKML-Reference: <49BA06E2.7080807@cn.fujitsu.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      b478b782
  5. 13 Mar, 2009 36 commits