lkml.org 
[lkml]   [2009]   [Mar]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [GIT PULL] tracing: use raw spinlocks for trace_vprintk
From
Date
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);
>


\
 
 \ /
  Last update: 2009-03-11 08:03    [W:0.096 / U:0.672 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site