Messages in this thread Patch in this message | | | From | Joel Fernandes <> | Subject | [PATCH RFC v5 1/6] softirq: reorder trace_softirqs_on to prevent lockdep splat | Date | Mon, 30 Apr 2018 18:41:59 -0700 |
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I'm able to reproduce a lockdep splat when CONFIG_PROVE_LOCKING=y and CONFIG_PREEMPTIRQ_EVENTS=y.
$ echo 1 > /d/tracing/events/preemptirq/preempt_enable/enable
Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Zilstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Thomas Glexiner <tglx@linutronix.de> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Fenguang Wu <fengguang.wu@intel.com> Cc: Baohong Liu <baohong.liu@intel.com> Cc: Vedang Patel <vedang.patel@intel.com> Cc: kernel-team@android.com Signed-off-by: Joel Fernandes <joelaf@google.com> --- kernel/softirq.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c index 24d243ef8e71..47e2f61938c0 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -139,9 +139,13 @@ static void __local_bh_enable(unsigned int cnt) { lockdep_assert_irqs_disabled(); + if (preempt_count() == cnt) + trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip()); + if (softirq_count() == (cnt & SOFTIRQ_MASK)) trace_softirqs_on(_RET_IP_); - preempt_count_sub(cnt); + + __preempt_count_sub(cnt); } /* -- 2.17.0.441.gb46fe60e1d-goog
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