From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [for-next][PATCH 08/15] tracing: Use in_serving_softirq() to deduct softirq status.
Date: Wed, 03 Feb 2021 11:05:25 -0500 [thread overview]
Message-ID: <20210203160549.825691017@goodmis.org> (raw)
In-Reply-To: 20210203160517.982448432@goodmis.org
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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>
---
kernel/trace/trace.c | 3 +--
1 file changed, 1 insertion(+), 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())
--
2.29.2
next prev parent reply other threads:[~2021-02-03 16:09 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 16:05 [for-next][PATCH 00/15] tracing: Updates for 5.12 Steven Rostedt
2021-02-03 16:05 ` [for-next][PATCH 01/15] tracing: Add printf attribute to log function Steven Rostedt
2021-02-03 16:05 ` [for-next][PATCH 02/15] tracing: Update trace_ignore_this_task() kernel-doc comment Steven Rostedt
2021-02-03 16:05 ` [for-next][PATCH 03/15] tracing: Remove get/put_cpu() from function_trace_init Steven Rostedt
2021-02-03 16:05 ` [for-next][PATCH 04/15] ring-buffer: Remove cpu_buffer argument from the rb_inc_page() Steven Rostedt
2021-02-03 16:05 ` [for-next][PATCH 05/15] ring-buffer: Drop unneeded check in ring_buffer_resize() Steven Rostedt
2021-02-03 16:05 ` [for-next][PATCH 07/15] tracing: Inline tracing_gen_ctx_flags() Steven Rostedt
2021-02-03 16:05 ` Steven Rostedt [this message]
2021-02-03 16:05 ` [for-next][PATCH 09/15] tracing: Remove NULL check from current in tracing_generic_entry_update() Steven Rostedt
2021-02-03 16:05 ` [for-next][PATCH 10/15] tracing: Fix spelling mistake in Kconfig "infinit" -> "infinite" Steven Rostedt
2021-02-03 16:05 ` [for-next][PATCH 11/15] tracing: Fix spelling of controlling in uprobes Steven Rostedt
2021-02-03 16:05 ` [for-next][PATCH 12/15] tracing: Fix a kernel doc warning Steven Rostedt
2021-02-03 16:05 ` [for-next][PATCH 13/15] tracing: Remove definition of DEBUG in trace_mmiotrace.c Steven Rostedt
2021-02-03 16:05 ` [for-next][PATCH 14/15] tracepoint: Do not fail unregistering a probe due to memory failure Steven Rostedt
2021-02-03 17:05 ` Peter Zijlstra
2021-02-03 17:09 ` Peter Zijlstra
2021-02-03 17:23 ` Steven Rostedt
2021-02-03 17:57 ` Mathieu Desnoyers
2021-02-04 16:50 ` Steven Rostedt
2021-02-03 17:57 ` [PATCH 1/1] tracepoint: cleanup: do not fail unregistration Mathieu Desnoyers
2021-02-04 17:47 ` Steven Rostedt
2021-02-03 16:05 ` [for-next][PATCH 15/15] kernel: trace: preemptirq_delay_test: add cpu affinity Steven Rostedt
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