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ring-buffer: Add ring_buffer_record_is_on_cpu()

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Add the function ring_buffer_record_is_on_cpu() that returns true if the
ring buffer for a give CPU is writable and false otherwise.

Also add tracer_tracing_is_on_cpu() to return if the ring buffer for a
given CPU is writeable for a given trace_array.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20250505212236.059853898@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt
2025-05-05 17:21:13 -04:00
committed by Steven Rostedt (Google)
parent 969043af15
commit 092a38565e
3 changed files with 34 additions and 0 deletions
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1
include/linux/ring_buffer.h
View File

@@ -192,6 +192,7 @@ void ring_buffer_record_off(struct trace_buffer *buffer);
void ring_buffer_record_on(struct trace_buffer *buffer);
bool ring_buffer_record_is_on(struct trace_buffer *buffer);
bool ring_buffer_record_is_set_on(struct trace_buffer *buffer);
bool ring_buffer_record_is_on_cpu(struct trace_buffer *buffer, int cpu);
void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu);
void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu);

18
kernel/trace/ring_buffer.c
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@@ -4882,6 +4882,24 @@ bool ring_buffer_record_is_set_on(struct trace_buffer *buffer)
return !(atomic_read(&buffer->record_disabled) & RB_BUFFER_OFF);
}
/**
* ring_buffer_record_is_on_cpu - return true if the ring buffer can write
* @buffer: The ring buffer to see if write is enabled
* @cpu: The CPU to test if the ring buffer can write too
*
* Returns true if the ring buffer is in a state that it accepts writes
* for a particular CPU.
*/
bool ring_buffer_record_is_on_cpu(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
cpu_buffer = buffer->buffers[cpu];
return ring_buffer_record_is_set_on(buffer) &&
!atomic_read(&cpu_buffer->record_disabled);
}
/**
* ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer
* @buffer: The ring buffer to stop writes to.

15
kernel/trace/trace.h
View File

@@ -673,6 +673,21 @@ struct dentry *trace_create_file(const char *name,
void *data,
const struct file_operations *fops);
/**
* tracer_tracing_is_on_cpu - show real state of ring buffer enabled on for a cpu
* @tr : the trace array to know if ring buffer is enabled
* @cpu: The cpu buffer to check if enabled
*
* Shows real state of the per CPU buffer if it is enabled or not.
*/
static inline bool tracer_tracing_is_on_cpu(struct trace_array *tr, int cpu)
{
if (tr->array_buffer.buffer)
return ring_buffer_record_is_on_cpu(tr->array_buffer.buffer, cpu);
return false;
}
int tracing_init_dentry(void);
struct ring_buffer_event;