From 4fe8c3048cd8280a54256bca9cac2007bd546c33 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 12 May 2008 21:20:54 +0200 Subject: ftrace: printk and trace irqsoff and wakeups printk called from wakeup critical timings and irqs off can cause deadlocks since printk might do a wakeup itself. If the call to printk happens with the runqueue lock held, it can deadlock. This patch protects the printk from being called in trace irqs off with a test to see if the runqueue for the current CPU is locked. If it is locked, the printk is skipped. The wakeup always holds the runqueue lock, so the printk is simply removed. Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- kernel/trace/trace_sched_wakeup.c | 13 ------------- 1 file changed, 13 deletions(-) (limited to 'kernel/trace/trace_sched_wakeup.c') diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c index 2a012423f9d0..5948011006bc 100644 --- a/kernel/trace/trace_sched_wakeup.c +++ b/kernel/trace/trace_sched_wakeup.c @@ -106,19 +106,6 @@ wakeup_sched_switch(struct task_struct *prev, struct task_struct *next) update_max_tr(tr, wakeup_task, wakeup_cpu); - if (tracing_thresh) { - printk(KERN_INFO "(%16s-%-5d|#%d):" - " %lu us wakeup latency violates %lu us threshold.\n", - wakeup_task->comm, wakeup_task->pid, - raw_smp_processor_id(), - latency, nsecs_to_usecs(tracing_thresh)); - } else { - printk(KERN_INFO "(%16s-%-5d|#%d):" - " new %lu us maximum wakeup latency.\n", - wakeup_task->comm, wakeup_task->pid, - cpu, latency); - } - out_unlock: __wakeup_reset(tr); spin_unlock_irqrestore(&wakeup_lock, flags); -- cgit v1.2.3