diff options
Diffstat (limited to 'debian/patches-rt/0003-tracing-Use-in_serving_softirq-to-deduct-softirq-sta.patch')
| -rw-r--r-- | debian/patches-rt/0003-tracing-Use-in_serving_softirq-to-deduct-softirq-sta.patch | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/debian/patches-rt/0003-tracing-Use-in_serving_softirq-to-deduct-softirq-sta.patch b/debian/patches-rt/0003-tracing-Use-in_serving_softirq-to-deduct-softirq-sta.patch new file mode 100644 index 000000000..334c9bb82 --- /dev/null +++ b/debian/patches-rt/0003-tracing-Use-in_serving_softirq-to-deduct-softirq-sta.patch @@ -0,0 +1,42 @@ +From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Date: Wed, 3 Feb 2021 11:05:25 -0500 +Subject: [PATCH 3/4] tracing: Use in_serving_softirq() to deduct softirq + status. +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.21-rt34.tar.xz + +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> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + kernel/trace/trace.c | 3 +-- + 1 file changed, 1 insertion(+), 2 deletions(-) + +--- a/kernel/trace/trace.c ++++ b/kernel/trace/trace.c +@@ -2589,8 +2589,7 @@ unsigned int tracing_gen_ctx_irq_test(un + 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()) |