Messages in this thread | | | Subject | Re: [GIT PULL] tracing: use raw spinlocks for trace_vprintk | From | Peter Zijlstra <> | Date | Wed, 11 Mar 2009 07:59:24 +0100 |
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On Tue, 2009-03-10 at 21:26 -0400, Steven Rostedt wrote:
> commit 80370cb758e7ca2692cd9fb5e413d970b1f4b2b2 > Author: Steven Rostedt <srostedt@redhat.com> > Date: Tue Mar 10 17:16:35 2009 -0400 > > tracing: use raw spinlocks for trace_vprintk > > Impact: prevent locking up by lockdep tracer > > The lockdep tracer uses trace_vprintk and thus trace_vprintk can not > call back into lockdep without locking up.
Hmm, I did this when I posted the lockdep tracepoints, so someone then did a bad copy/paste job when renaming ftrace_printk or something?
See efed792d6738964f399a508ef9e831cd60fa4657
> Signed-off-by: Steven Rostedt <srostedt@redhat.com> > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 8c6a902..4c97947 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -1176,7 +1176,8 @@ void trace_graph_return(struct ftrace_graph_ret *trace) > */ > int trace_vprintk(unsigned long ip, int depth, const char *fmt, va_list args) > { > - static DEFINE_SPINLOCK(trace_buf_lock); > + static raw_spinlock_t trace_buf_lock = > + (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; > static u32 trace_buf[TRACE_BUF_SIZE]; > > struct ring_buffer_event *event; > @@ -1201,7 +1202,9 @@ int trace_vprintk(unsigned long ip, int depth, const char *fmt, va_list args) > if (unlikely(atomic_read(&data->disabled))) > goto out; > > - spin_lock_irqsave(&trace_buf_lock, flags); > + /* Lockdep uses trace_printk for lock tracing */ > + local_irq_save(flags);
Shouldn't you also use raw_local_irq_save() and friends?
> + __raw_spin_lock(&trace_buf_lock); > len = vbin_printf(trace_buf, TRACE_BUF_SIZE, fmt, args); > > if (len > TRACE_BUF_SIZE || len < 0) > @@ -1220,7 +1223,8 @@ int trace_vprintk(unsigned long ip, int depth, const char *fmt, va_list args) > ring_buffer_unlock_commit(tr->buffer, event); > > out_unlock: > - spin_unlock_irqrestore(&trace_buf_lock, flags); > + __raw_spin_unlock(&trace_buf_lock); > + local_irq_restore(flags); > > out: > ftrace_preempt_enable(resched); >
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