[PATCH] blktrace: fix 'BUG: sleeping function called from invalid context' in case of PREEMPT_RT

[Ming Lei]

trace_note_tsk() is called by __blk_add_trace(), which is covered by RCU read 
lock.
So in case of PREEMPT_RT, warning of 'BUG: sleeping function called from 
invalid context'
will be triggered because spin lock is converted to rtmutex.

Fix the issue by converting running_trace_lock into raw_spin_lock().

Cc: Christoph Hellwig <h...@lst.de>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ming Lei <ming....@redhat.com>
---
 kernel/trace/blktrace.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 2c5b3c5317c2..53dc876d669d 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -34,7 +34,7 @@ static struct trace_array *blk_tr;
 static bool blk_tracer_enabled __read_mostly;
 
 static LIST_HEAD(running_trace_list);
-static __cacheline_aligned_in_smp DEFINE_SPINLOCK(running_trace_lock);
+static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(running_trace_lock);
 
 /* Select an alternative, minimalistic output than the original one */
 #define TRACE_BLK_OPT_CLASSIC  0x1
@@ -121,12 +121,12 @@ static void trace_note_tsk(struct task_struct *tsk)
        struct blk_trace *bt;
 
        tsk->btrace_seq = blktrace_seq;
-       spin_lock_irqsave(&running_trace_lock, flags);
+       raw_spin_lock_irqsave(&running_trace_lock, flags);
        list_for_each_entry(bt, &running_trace_list, running_list) {
                trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm,
                           sizeof(tsk->comm), 0);
        }
-       spin_unlock_irqrestore(&running_trace_lock, flags);
+       raw_spin_unlock_irqrestore(&running_trace_lock, flags);
 }
 
 static void trace_note_time(struct blk_trace *bt)
@@ -669,9 +669,9 @@ static int __blk_trace_startstop(struct request_queue *q, 
int start)
                        blktrace_seq++;
                        smp_mb();
                        bt->trace_state = Blktrace_running;
-                       spin_lock_irq(&running_trace_lock);
+                       raw_spin_lock_irq(&running_trace_lock);
                        list_add(&bt->running_list, &running_trace_list);
-                       spin_unlock_irq(&running_trace_lock);
+                       raw_spin_unlock_irq(&running_trace_lock);
 
                        trace_note_time(bt);
                        ret = 0;
@@ -679,9 +679,9 @@ static int __blk_trace_startstop(struct request_queue *q, 
int start)
        } else {
                if (bt->trace_state == Blktrace_running) {
                        bt->trace_state = Blktrace_stopped;
-                       spin_lock_irq(&running_trace_lock);
+                       raw_spin_lock_irq(&running_trace_lock);
                        list_del_init(&bt->running_list);
-                       spin_unlock_irq(&running_trace_lock);
+                       raw_spin_unlock_irq(&running_trace_lock);
                        relay_flush(bt->rchan);
                        ret = 0;
                }
-- 
2.28.0