Messages in this thread Patch in this message | | | Date | Wed, 13 Jan 2010 19:09:22 +0100 (CET) | From | John Kacur <> | Subject | Re: [PATCH 14/26] trace: Convert various locks to raw_spinlock |
| |
On Wed, 13 Jan 2010, Steven Rostedt wrote:
> On Wed, 2010-01-13 at 16:36 +0100, John Kacur wrote: > > > > On Wed, 13 Jan 2010, Steven Rostedt wrote: > > > > > > Thanks for the review Steve and Frederic - I'll spin a new patch that > > doesn't convert tracing_start_lock. > > > > However, let's give it some good testing in preempt-rt, because we may > > have forgotten over time, why we converted these locks. > > Well, I think we just never unconverted them :-) I think we took the > paranoid approach and converted all locks in the trace directory to raw. > In fact, I think I even had a script to do it. > > -- Steve
Okay, here is the new version of the patch. Frederic and Steve, can I have Acked-bys before I push to git?
Thanks
From ee03cc607493e58f34bf93afa2b8a23da5510927 Mon Sep 17 00:00:00 2001 From: John Kacur <jkacur@redhat.com> Date: Sun, 10 Jan 2010 03:09:48 +0100 Subject: [PATCH] trace: Convert reader_lock and max_trace_lock to raw_spinlocks
Convert reader_lock and max_trace_lock to raw_spinlock. These locks cannot sleep in preempt-rt because they are called with interrupts disabled. This should have zero-impact on mainline.
See also: 87654a70523a8c5baadcbbc07d80cbae8f912837
Signed-off-by: John Kacur <jkacur@redhat.com> --- kernel/trace/ring_buffer.c | 53 +++++++++++++++++++++-------------------- kernel/trace/trace_irqsoff.c | 10 +++++-- 2 files changed, 34 insertions(+), 29 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 2326b04..56b073c 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -422,7 +422,8 @@ int ring_buffer_print_page_header(struct trace_seq *s) struct ring_buffer_per_cpu { int cpu; struct ring_buffer *buffer; - spinlock_t reader_lock; /* serialize readers */ + /* Can be called with interrupts disabled via ftrace_dump */ + raw_spinlock_t reader_lock; /* serialize readers */ arch_spinlock_t lock; struct lock_class_key lock_key; struct list_head *pages; @@ -996,7 +997,7 @@ rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) cpu_buffer->cpu = cpu; cpu_buffer->buffer = buffer; - spin_lock_init(&cpu_buffer->reader_lock); + raw_spin_lock_init(&cpu_buffer->reader_lock); lockdep_set_class(&cpu_buffer->reader_lock, buffer->reader_lock_key); cpu_buffer->lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; @@ -1193,7 +1194,7 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) struct list_head *p; unsigned i; - spin_lock_irq(&cpu_buffer->reader_lock); + raw_spin_lock_irq(&cpu_buffer->reader_lock); rb_head_page_deactivate(cpu_buffer); for (i = 0; i < nr_pages; i++) { @@ -1210,7 +1211,7 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) rb_reset_cpu(cpu_buffer); rb_check_pages(cpu_buffer); - spin_unlock_irq(&cpu_buffer->reader_lock); + raw_spin_unlock_irq(&cpu_buffer->reader_lock); } static void @@ -1221,7 +1222,7 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer, struct list_head *p; unsigned i; - spin_lock_irq(&cpu_buffer->reader_lock); + raw_spin_lock_irq(&cpu_buffer->reader_lock); rb_head_page_deactivate(cpu_buffer); for (i = 0; i < nr_pages; i++) { @@ -1235,7 +1236,7 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer, rb_reset_cpu(cpu_buffer); rb_check_pages(cpu_buffer); - spin_unlock_irq(&cpu_buffer->reader_lock); + raw_spin_unlock_irq(&cpu_buffer->reader_lock); } /** @@ -2735,9 +2736,9 @@ void ring_buffer_iter_reset(struct ring_buffer_iter *iter) cpu_buffer = iter->cpu_buffer; - spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); rb_iter_reset(iter); - spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); } EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); @@ -3157,12 +3158,12 @@ ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) again: local_irq_save(flags); if (dolock) - spin_lock(&cpu_buffer->reader_lock); + raw_spin_lock(&cpu_buffer->reader_lock); event = rb_buffer_peek(cpu_buffer, ts); if (event && event->type_len == RINGBUF_TYPE_PADDING) rb_advance_reader(cpu_buffer); if (dolock) - spin_unlock(&cpu_buffer->reader_lock); + raw_spin_unlock(&cpu_buffer->reader_lock); local_irq_restore(flags); if (event && event->type_len == RINGBUF_TYPE_PADDING) @@ -3187,9 +3188,9 @@ ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) unsigned long flags; again: - spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); event = rb_iter_peek(iter, ts); - spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); if (event && event->type_len == RINGBUF_TYPE_PADDING) goto again; @@ -3225,14 +3226,14 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) cpu_buffer = buffer->buffers[cpu]; local_irq_save(flags); if (dolock) - spin_lock(&cpu_buffer->reader_lock); + raw_spin_lock(&cpu_buffer->reader_lock); event = rb_buffer_peek(cpu_buffer, ts); if (event) rb_advance_reader(cpu_buffer); if (dolock) - spin_unlock(&cpu_buffer->reader_lock); + raw_spin_unlock(&cpu_buffer->reader_lock); local_irq_restore(flags); out: @@ -3278,11 +3279,11 @@ ring_buffer_read_start(struct ring_buffer *buffer, int cpu) atomic_inc(&cpu_buffer->record_disabled); synchronize_sched(); - spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); arch_spin_lock(&cpu_buffer->lock); rb_iter_reset(iter); arch_spin_unlock(&cpu_buffer->lock); - spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); return iter; } @@ -3319,7 +3320,7 @@ ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; unsigned long flags; - spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); again: event = rb_iter_peek(iter, ts); if (!event) @@ -3330,7 +3331,7 @@ ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) rb_advance_iter(iter); out: - spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); return event; } @@ -3396,7 +3397,7 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) atomic_inc(&cpu_buffer->record_disabled); - spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing))) goto out; @@ -3408,7 +3409,7 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) arch_spin_unlock(&cpu_buffer->lock); out: - spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); atomic_dec(&cpu_buffer->record_disabled); } @@ -3446,10 +3447,10 @@ int ring_buffer_empty(struct ring_buffer *buffer) cpu_buffer = buffer->buffers[cpu]; local_irq_save(flags); if (dolock) - spin_lock(&cpu_buffer->reader_lock); + raw_spin_lock(&cpu_buffer->reader_lock); ret = rb_per_cpu_empty(cpu_buffer); if (dolock) - spin_unlock(&cpu_buffer->reader_lock); + raw_spin_unlock(&cpu_buffer->reader_lock); local_irq_restore(flags); if (!ret) @@ -3480,10 +3481,10 @@ int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) cpu_buffer = buffer->buffers[cpu]; local_irq_save(flags); if (dolock) - spin_lock(&cpu_buffer->reader_lock); + raw_spin_lock(&cpu_buffer->reader_lock); ret = rb_per_cpu_empty(cpu_buffer); if (dolock) - spin_unlock(&cpu_buffer->reader_lock); + raw_spin_unlock(&cpu_buffer->reader_lock); local_irq_restore(flags); return ret; @@ -3678,7 +3679,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer, if (!bpage) goto out; - spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); reader = rb_get_reader_page(cpu_buffer); if (!reader) @@ -3753,7 +3754,7 @@ int ring_buffer_read_page(struct ring_buffer *buffer, ret = read; out_unlock: - spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); out: return ret; diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c index 2974bc7..7125f71 100644 --- a/kernel/trace/trace_irqsoff.c +++ b/kernel/trace/trace_irqsoff.c @@ -23,7 +23,11 @@ static int tracer_enabled __read_mostly; static DEFINE_PER_CPU(int, tracing_cpu); -static DEFINE_SPINLOCK(max_trace_lock); +/* + * This lock is always taken with interrupts disabled, + * and therefore cannot sleep in preempt-rt. + */ +static DEFINE_RAW_SPINLOCK(max_trace_lock); enum { TRACER_IRQS_OFF = (1 << 1), @@ -144,7 +148,7 @@ check_critical_timing(struct trace_array *tr, if (!report_latency(delta)) goto out; - spin_lock_irqsave(&max_trace_lock, flags); + raw_spin_lock_irqsave(&max_trace_lock, flags); /* check if we are still the max latency */ if (!report_latency(delta)) @@ -167,7 +171,7 @@ check_critical_timing(struct trace_array *tr, max_sequence++; out_unlock: - spin_unlock_irqrestore(&max_trace_lock, flags); + raw_spin_unlock_irqrestore(&max_trace_lock, flags); out: data->critical_sequence = max_sequence; -- 1.6.5.2
| |