[PATCH RT 5/6] sched: Better debug output for might sleep
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2012-10-10 13:40:09
Also in:
lkml
Subsystem:
scheduler, the rest · Maintainers:
Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
From: Thomas Gleixner <redacted> might sleep can tell us where interrupts have been disabled, but we have no idea what disabled preemption. Add some debug infrastructure. Cc: stable-rt@vger.kernel.org Signed-off-by: Thomas Gleixner <redacted> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> --- include/linux/sched.h | 4 ++++ kernel/sched.c | 23 +++++++++++++++++++++-- 2 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8155129..a179dd0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h@@ -1606,6 +1606,10 @@ struct task_struct { int kmap_idx; pte_t kmap_pte[KM_TYPE_NR]; #endif + +#ifdef CONFIG_DEBUG_PREEMPT + unsigned long preempt_disable_ip; +#endif }; #ifdef CONFIG_PREEMPT_RT_FULL
diff --git a/kernel/sched.c b/kernel/sched.c
index ea235b6..38f9104 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c@@ -4121,8 +4121,13 @@ void __kprobes add_preempt_count(int val) DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= PREEMPT_MASK - 10); #endif - if (preempt_count() == val) - trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); + if (preempt_count() == val) { + unsigned long ip = get_parent_ip(CALLER_ADDR1); +#ifdef CONFIG_DEBUG_PREEMPT + current->preempt_disable_ip = ip; +#endif + trace_preempt_off(CALLER_ADDR0, ip); + } } EXPORT_SYMBOL(add_preempt_count);
@@ -4164,6 +4169,13 @@ static noinline void __schedule_bug(struct task_struct *prev) print_modules(); if (irqs_disabled()) print_irqtrace_events(prev); +#ifdef DEBUG_PREEMPT + if (in_atomic_preempt_off()) { + pr_err("Preemption disabled at:"); + print_ip_sym(current->preempt_disable_ip); + pr_cont("\n"); + } +#endif if (regs) show_regs(regs);
@@ -8483,6 +8495,13 @@ void __might_sleep(const char *file, int line, int preempt_offset) debug_show_held_locks(current); if (irqs_disabled()) print_irqtrace_events(current); +#ifdef DEBUG_PREEMPT + if (!preempt_count_equals(preempt_offset)) { + pr_err("Preemption disabled at:"); + print_ip_sym(current->preempt_disable_ip); + pr_cont("\n"); + } +#endif dump_stack(); #endif }
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1.7.10.4