ring_buffer_per_cpu::mapped tracks if a ring-buffer is either mapped by user-space or if it is a persistent buffer. We already have user_mapped for the former and ring_meta for the latter. Get rid of mapped and instead create rb_is_static(). A static ring-buffer cannot be resized, swapped or have its pages extracted.
Signed-off-by: Vincent Donnefort <[email protected]> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index d128bda5b661..8dae55ddbe15 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -508,7 +508,7 @@ struct ring_buffer_per_cpu { int cpu; atomic_t record_disabled; atomic_t resize_disabled; - struct trace_buffer *buffer; + struct trace_buffer *buffer; raw_spinlock_t reader_lock; /* serialize readers */ arch_spinlock_t lock; struct lock_class_key lock_key; @@ -546,7 +546,6 @@ struct ring_buffer_per_cpu { /* pages removed since last reset */ unsigned long pages_removed; - unsigned int mapped; unsigned int user_mapped; /* user space mapping */ struct mutex mapping_lock; struct buffer_page **subbuf_ids; /* ID to subbuf VA */ @@ -614,6 +613,11 @@ static __always_inline unsigned int rb_max_data_size(struct trace_buffer *buffer return rb_subbuf_capacity(buffer) - RB_EVNT_HDR_SIZE - sizeof(event->array[0]); } +static bool rb_is_static(struct ring_buffer_per_cpu *cpu_buffer) +{ + return cpu_buffer->user_mapped || cpu_buffer->remote || cpu_buffer->ring_meta; +} + struct ring_buffer_iter { struct ring_buffer_per_cpu *cpu_buffer; unsigned long head; @@ -2544,7 +2548,6 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu) * Range mapped buffers have the same restrictions as memory * mapped ones do. */ - cpu_buffer->mapped = 1; cpu_buffer->ring_meta = rb_range_meta(buffer, nr_pages, cpu); bpage->page = rb_range_buffer(cpu_buffer, 0); if (!bpage->page) @@ -6634,12 +6637,11 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) rb_head_page_activate(cpu_buffer); cpu_buffer->pages_removed = 0; - if (cpu_buffer->mapped) { - rb_update_meta_page(cpu_buffer); - if (cpu_buffer->ring_meta) { - struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; - meta->commit_buffer = meta->head_buffer; - } + rb_update_meta_page(cpu_buffer); + if (cpu_buffer->ring_meta) { + struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; + + meta->commit_buffer = meta->head_buffer; } } @@ -6888,8 +6890,8 @@ int ring_buffer_swap_cpu(struct trace_buffer *buffer_a, cpu_buffer_a = buffer_a->buffers[cpu]; cpu_buffer_b = buffer_b->buffers[cpu]; - /* It's up to the callers to not try to swap mapped buffers */ - if (WARN_ON_ONCE(cpu_buffer_a->mapped || cpu_buffer_b->mapped)) + /* It's up to the callers to not try to swap static buffers */ + if (WARN_ON_ONCE(rb_is_static(cpu_buffer_a) || rb_is_static(cpu_buffer_b))) return -EBUSY; /* At least make sure the two buffers are somewhat the same */ @@ -7101,7 +7103,6 @@ int ring_buffer_read_page(struct trace_buffer *buffer, unsigned int size; unsigned int read; u64 save_timestamp; - bool force_memcpy; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return -1; @@ -7140,8 +7141,6 @@ int ring_buffer_read_page(struct trace_buffer *buffer, /* Check if any events were dropped */ missed_events = cpu_buffer->lost_events; - force_memcpy = cpu_buffer->mapped || cpu_buffer->remote; - /* * If this page has been partially read or * if len is not big enough to read the rest of the page or @@ -7151,7 +7150,7 @@ int ring_buffer_read_page(struct trace_buffer *buffer, */ if (read || (len < (size - read)) || cpu_buffer->reader_page == cpu_buffer->commit_page || - force_memcpy) { + rb_is_static(cpu_buffer)) { struct buffer_data_page *rpage = cpu_buffer->reader_page->page; unsigned int rpos = read; unsigned int pos = 0; @@ -7598,11 +7597,7 @@ static int __rb_inc_dec_mapped(struct ring_buffer_per_cpu *cpu_buffer, lockdep_assert_held(&cpu_buffer->mapping_lock); - /* mapped is always greater or equal to user_mapped */ - if (WARN_ON(cpu_buffer->mapped < cpu_buffer->user_mapped)) - return -EINVAL; - - if (inc && cpu_buffer->mapped == UINT_MAX) + if (inc && cpu_buffer->user_mapped == UINT_MAX) return -EBUSY; if (WARN_ON(!inc && cpu_buffer->user_mapped == 0)) @@ -7611,13 +7606,10 @@ static int __rb_inc_dec_mapped(struct ring_buffer_per_cpu *cpu_buffer, mutex_lock(&cpu_buffer->buffer->mutex); raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); - if (inc) { + if (inc) cpu_buffer->user_mapped++; - cpu_buffer->mapped++; - } else { + else cpu_buffer->user_mapped--; - cpu_buffer->mapped--; - } raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); mutex_unlock(&cpu_buffer->buffer->mutex); @@ -7789,7 +7781,6 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu, if (!err) { raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); /* This is the first time it is mapped by user */ - cpu_buffer->mapped++; cpu_buffer->user_mapped = 1; raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); } else { @@ -7846,8 +7837,6 @@ int ring_buffer_unmap(struct trace_buffer *buffer, int cpu) raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); /* This is the last user space mapping */ - if (!WARN_ON_ONCE(cpu_buffer->mapped < cpu_buffer->user_mapped)) - cpu_buffer->mapped--; cpu_buffer->user_mapped = 0; raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); -- 2.55.0.654.g21b8a5bc05-goog
