From 8a59cb301183f5f689a32468046abc399b3c6f4e Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Tue, 24 Oct 2023 13:32:28 +0000 Subject: [PATCH] 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 Change-Id: I35cd4d9cef24e64f2dc3afad85d90d588c09e5f0 Signed-off-by: Greg Kroah-Hartman --- include/linux/ring_buffer.h | 2 +- kernel/trace/ring_buffer.c | 54 +++++++++++++------------------------ kernel/trace/trace.c | 2 +- 3 files changed, 21 insertions(+), 37 deletions(-) diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index b73950772299..1a40277b512c 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -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 diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 078cee0d6b4d..45f4659658e8 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -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; - } - + 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; diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 80c13b5adbef..6552f7cc2331 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -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