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| author | Wander Lairson Costa <wander@redhat.com> | 2021-12-20 22:28:27 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-12-20 23:50:14 +0300 |
| commit | 361c81dbc58c8aa230e1f2d556045fa7bc3eb4a3 (patch) | |
| tree | ce8ee18c100f6ddaedfb01f8da170c7d958dd591 /kernel/trace/blktrace.c | |
| parent | 5ef1630586317e92c9ebd7b4ce48f393b7ff790f (diff) | |
| download | linux-361c81dbc58c8aa230e1f2d556045fa7bc3eb4a3.tar.xz | |
blktrace: switch trace spinlock to a raw spinlock
The running_trace_lock protects running_trace_list and is acquired
within the tracepoint which implies disabled preemption. The spinlock_t
typed lock can not be acquired with disabled preemption on PREEMPT_RT
because it becomes a sleeping lock.
The runtime of the tracepoint depends on the number of entries in
running_trace_list and has no limit. The blk-tracer is considered debug
code and higher latencies here are okay.
Make running_trace_lock a raw_spinlock_t.
Signed-off-by: Wander Lairson Costa <wander@redhat.com>
Link: https://lore.kernel.org/r/20211220192827.38297-1-wander@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'kernel/trace/blktrace.c')
| -rw-r--r-- | kernel/trace/blktrace.c | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index 431e41bc4c23..af68a67179b4 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) @@ -666,9 +666,9 @@ 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; @@ -676,9 +676,9 @@ 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; } @@ -1608,9 +1608,9 @@ static int blk_trace_remove_queue(struct request_queue *q) 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); } |