diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2021-01-25 20:45:10 +0100 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2021-02-02 17:02:06 -0500 |
| commit | fe427886bf41279085e0707cced41150dbcd8512 (patch) | |
| tree | 20577d28c052e895e9ed58e7e1df35181471c52a /kernel/trace/trace.c | |
| parent | 0c02006e6f5b0a3e73499bbf5943d9174c5ed640 (diff) | |
tracing: Use in_serving_softirq() to deduct softirq status.
PREEMPT_RT does not report "serving softirq" because the tracing core
looks at the preemption counter while PREEMPT_RT does not update it
while processing softirqs in order to remain preemptible. The
information is stored somewhere else.
The in_serving_softirq() macro and the SOFTIRQ_OFFSET define are still
working but not on the preempt-counter.
Use in_serving_softirq() macro which works on PREEMPT_RT. On !PREEMPT_RT
the compiler (gcc-10 / clang-11) is smart enough to optimize the
in_serving_softirq() related read of the preemption counter away.
The only difference I noticed by using in_serving_softirq() on
!PREEMPT_RT is that gcc-10 implemented tracing_gen_ctx_flags() as
reading FLAG, jmp _tracing_gen_ctx_flags(). Without in_serving_softirq()
it inlined _tracing_gen_ctx_flags() into tracing_gen_ctx_flags().
Link: https://lkml.kernel.org/r/20210125194511.3924915-4-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 584fa2a1304a..75620c29e904 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2590,8 +2590,7 @@ unsigned int tracing_gen_ctx_irq_test(unsigned int irqs_status) trace_flags |= TRACE_FLAG_NMI; if (pc & HARDIRQ_MASK) trace_flags |= TRACE_FLAG_HARDIRQ; - - if (pc & SOFTIRQ_OFFSET) + if (in_serving_softirq()) trace_flags |= TRACE_FLAG_SOFTIRQ; if (tif_need_resched()) |