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ring-buffer: Make ring_buffer_{un}map() simpler with guard(mutex)

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Convert the taking of the buffer->mutex and the cpu_buffer->mapping_lock
over to guard(mutex) and simplify the ring_buffer_map() and
ring_buffer_unmap() functions.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Vincent Donnefort <vdonnefort@google.com>
Link: https://lore.kernel.org/20250527122009.267efb72@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt
2025-05-27 12:20:09 -04:00
committed by Steven Rostedt (Google)
parent b2e7c6ed26
commit 60bc720e10
1 changed files with 11 additions and 24 deletions
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35
kernel/trace/ring_buffer.c
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@@ -7161,36 +7161,34 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu,
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long flags, *subbuf_ids;
int err = 0;
int err;
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return -EINVAL;
cpu_buffer = buffer->buffers[cpu];
mutex_lock(&cpu_buffer->mapping_lock);
guard(mutex)(&cpu_buffer->mapping_lock);
if (cpu_buffer->user_mapped) {
err = __rb_map_vma(cpu_buffer, vma);
if (!err)
err = __rb_inc_dec_mapped(cpu_buffer, true);
mutex_unlock(&cpu_buffer->mapping_lock);
return err;
}
/* prevent another thread from changing buffer/sub-buffer sizes */
mutex_lock(&buffer->mutex);
guard(mutex)(&buffer->mutex);
err = rb_alloc_meta_page(cpu_buffer);
if (err)
goto unlock;
return err;
/* subbuf_ids include the reader while nr_pages does not */
subbuf_ids = kcalloc(cpu_buffer->nr_pages + 1, sizeof(*subbuf_ids), GFP_KERNEL);
if (!subbuf_ids) {
rb_free_meta_page(cpu_buffer);
err = -ENOMEM;
goto unlock;
return -ENOMEM;
}
atomic_inc(&cpu_buffer->resize_disabled);
@@ -7218,35 +7216,29 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu,
atomic_dec(&cpu_buffer->resize_disabled);
}
unlock:
mutex_unlock(&buffer->mutex);
mutex_unlock(&cpu_buffer->mapping_lock);
return err;
return 0;
}
int ring_buffer_unmap(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long flags;
int err = 0;
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return -EINVAL;
cpu_buffer = buffer->buffers[cpu];
mutex_lock(&cpu_buffer->mapping_lock);
guard(mutex)(&cpu_buffer->mapping_lock);
if (!cpu_buffer->user_mapped) {
err = -ENODEV;
goto out;
return -ENODEV;
} else if (cpu_buffer->user_mapped > 1) {
__rb_inc_dec_mapped(cpu_buffer, false);
goto out;
return 0;
}
mutex_lock(&buffer->mutex);
guard(mutex)(&buffer->mutex);
raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
/* This is the last user space mapping */
@@ -7261,12 +7253,7 @@ int ring_buffer_unmap(struct trace_buffer *buffer, int cpu)
rb_free_meta_page(cpu_buffer);
atomic_dec(&cpu_buffer->resize_disabled);
mutex_unlock(&buffer->mutex);
out:
mutex_unlock(&cpu_buffer->mapping_lock);
return err;
return 0;
}
int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu)