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Commit 8a59cb30 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
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Reapply "ANDROID: Revert "tracing/ring-buffer: Have polling block on watermark"" 



This reverts commit 541686ad47d2b3eb58a3d809322fe558b3b2c948, which
reapplys the original revert as the original is still causing crashes.

Bug: 263508491
Cc: Lee Jones <joneslee@google.com>
Change-Id: I35cd4d9cef24e64f2dc3afad85d90d588c09e5f0
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
parent 574430d8

include/linux/ring_buffer.h

+1 −1
Original line number Diff line number Diff line
@@ -99,7 +99,7 @@ __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *k 


int ring_buffer_wait(struct ring_buffer *buffer, int cpu, int full);

__poll_t ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,

			  struct file *filp, poll_table *poll_table, int full);

			  struct file *filp, poll_table *poll_table);





#define RING_BUFFER_ALL_CPUS -1

kernel/trace/ring_buffer.c

+19 −35
Original line number Diff line number Diff line
@@ -569,21 +569,6 @@ size_t ring_buffer_nr_dirty_pages(struct ring_buffer *buffer, int cpu) 
	return cnt - read;

}



static __always_inline bool full_hit(struct ring_buffer *buffer, int cpu, int full)

{

	struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];

	size_t nr_pages;

	size_t dirty;



	nr_pages = cpu_buffer->nr_pages;

	if (!nr_pages || !full)

		return true;



	dirty = ring_buffer_nr_dirty_pages(buffer, cpu);



	return (dirty * 100) > (full * nr_pages);

}



/*

 * rb_wake_up_waiters - wake up tasks waiting for ring buffer input

 *
@@ -679,20 +664,22 @@ int ring_buffer_wait(struct ring_buffer *buffer, int cpu, int full) 
		    !ring_buffer_empty_cpu(buffer, cpu)) {

			unsigned long flags;

			bool pagebusy;

			bool done;

			size_t nr_pages;

			size_t dirty;



			if (!full)

				break;



			raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);

			pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page;

			done = !pagebusy && full_hit(buffer, cpu, full);



			nr_pages = cpu_buffer->nr_pages;

			dirty = ring_buffer_nr_dirty_pages(buffer, cpu);

			if (!cpu_buffer->shortest_full ||

			    cpu_buffer->shortest_full > full)

				cpu_buffer->shortest_full = full;

			raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);

			if (done)

			if (!pagebusy &&

			    (!nr_pages || (dirty * 100) > full * nr_pages))

				break;

		}
@@ -713,7 +700,6 @@ int ring_buffer_wait(struct ring_buffer *buffer, int cpu, int full) 
 * @cpu: the cpu buffer to wait on

 * @filp: the file descriptor

 * @poll_table: The poll descriptor

 * @full: wait until the percentage of pages are available, if @cpu != RING_BUFFER_ALL_CPUS

 *

 * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon

 * as data is added to any of the @buffer's cpu buffers. Otherwise
@@ -723,14 +709,14 @@ int ring_buffer_wait(struct ring_buffer *buffer, int cpu, int full) 
 * zero otherwise.

 */

__poll_t ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,

			  struct file *filp, poll_table *poll_table, int full)

			  struct file *filp, poll_table *poll_table)

{

	struct ring_buffer_per_cpu *cpu_buffer;

	struct rb_irq_work *work;



	if (cpu == RING_BUFFER_ALL_CPUS) {

	if (cpu == RING_BUFFER_ALL_CPUS)

		work = &buffer->irq_work;

	} else {

	else {

		if (!cpumask_test_cpu(cpu, buffer->cpumask))

			return -EINVAL;
@@ -738,14 +724,8 @@ __poll_t ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu, 
		work = &cpu_buffer->irq_work;

	}



	if (full) {

		poll_wait(filp, &work->full_waiters, poll_table);

		work->full_waiters_pending = true;

	} else {

	poll_wait(filp, &work->waiters, poll_table);

	work->waiters_pending = true;

	}



	/*

	 * There's a tight race between setting the waiters_pending and

	 * checking if the ring buffer is empty.  Once the waiters_pending bit
@@ -761,9 +741,6 @@ __poll_t ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu, 
	 */

	smp_mb();



	if (full)

		return full_hit(buffer, cpu, full) ? EPOLLIN | EPOLLRDNORM : 0;



	if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) ||

	    (cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu)))

		return EPOLLIN | EPOLLRDNORM;
@@ -2674,6 +2651,10 @@ static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, 
static __always_inline void

rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer)

{

	size_t nr_pages;

	size_t dirty;

	size_t full;



	if (buffer->irq_work.waiters_pending) {

		buffer->irq_work.waiters_pending = false;

		/* irq_work_queue() supplies it's own memory barriers */
@@ -2697,7 +2678,10 @@ rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer) 


	cpu_buffer->last_pages_touch = local_read(&cpu_buffer->pages_touched);



	if (!full_hit(buffer, cpu_buffer->cpu, cpu_buffer->shortest_full))

	full = cpu_buffer->shortest_full;

	nr_pages = cpu_buffer->nr_pages;

	dirty = ring_buffer_nr_dirty_pages(buffer, cpu_buffer->cpu);

	if (full && nr_pages && (dirty * 100) <= full * nr_pages)

		return;



	cpu_buffer->irq_work.wakeup_full = true;

kernel/trace/trace.c

+1 −1
Original line number Diff line number Diff line
@@ -6036,7 +6036,7 @@ trace_poll(struct trace_iterator *iter, struct file *filp, poll_table *poll_tabl 
		return EPOLLIN | EPOLLRDNORM;

	else

		return ring_buffer_poll_wait(iter->trace_buffer->buffer, iter->cpu_file,

					     filp, poll_table, iter->tr->buffer_percent);

					     filp, poll_table);

}



static __poll_t