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[104.155.91.135]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49ce5533ffbsm309781515e9.3.2026.09.07.02.44.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Sep 2026 02:44:11 -0700 (PDT) Date: Mon, 7 Sep 2026 10:44:07 +0100 From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, linux-trace-kernel@vger.kernel.org Cc: mathieu.desnoyers@efficios.com, kernel-team@android.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1] ring-buffer: Rename ring_buffer_size() to ring_buffer_capacity() Message-ID: References: <20260907094238.3624013-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260907094238.3624013-1-vdonnefort@google.com> On Mon, Sep 07, 2026 at 10:42:38AM +0100, Vincent Donnefort wrote: > Since commit 8a5f63637890 ("ring-buffer: Fix subbuf resize race with ring > buffer readers"), "capacity" refers to the memory available for events > (excluding subbuffer headers) while "size" refers to the raw allocation. > ring_buffer_size() actually calculates this event capacity. Rename it to > ring_buffer_capacity() to align with this convention. > > Signed-off-by: Vincent Donnefort > > diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h > index afc7daa6ee7d..9e23ab66176b 100644 > --- a/include/linux/ring_buffer.h > +++ b/include/linux/ring_buffer.h > @@ -165,7 +165,7 @@ void ring_buffer_iter_reset(struct ring_buffer_iter *iter); > int ring_buffer_iter_empty(struct ring_buffer_iter *iter); > bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter); > > -unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu); > +unsigned long ring_buffer_capacity(struct trace_buffer *buffer, int cpu); > unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer); > > void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu); > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index 9c03a555a6ba..2940ff763354 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -6547,18 +6547,23 @@ void ring_buffer_iter_advance(struct ring_buffer_iter *iter) > EXPORT_SYMBOL_GPL(ring_buffer_iter_advance); > > /** > - * ring_buffer_size - return the size of the ring buffer (in bytes) > + * ring_buffer_capacity - return the capacity of the ring buffer (in bytes) > * @buffer: The ring buffer. > - * @cpu: The CPU to get ring buffer size from. > + * @cpu: The CPU to get ring buffer capacity from. > + * > + * Capacity is the total memory available for recording event data in the > + * ring buffer. It excludes subbufer headers. Of course, I manage to do a typo... "subbuffer" -- Vincent > + * > + * Returns the capacity in bytes, or 0 if the CPU is not set in the buffer mask. > */ > -unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu) > +unsigned long ring_buffer_capacity(struct trace_buffer *buffer, int cpu) > { > if (!cpumask_test_cpu(cpu, buffer->cpumask)) > return 0; > > return rb_subbuf_capacity(buffer) * buffer->buffers[cpu]->nr_pages; > } > -EXPORT_SYMBOL_GPL(ring_buffer_size); > +EXPORT_SYMBOL_GPL(ring_buffer_capacity); > > /** > * ring_buffer_max_event_size - return the max data size of an event > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 8658cad53cb5..f0251788ec75 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -4712,9 +4712,9 @@ void trace_set_buffer_entries(struct array_buffer *buf, unsigned long val) > static void update_buffer_entries(struct array_buffer *buf, int cpu) > { > if (cpu == RING_BUFFER_ALL_CPUS) { > - trace_set_buffer_entries(buf, ring_buffer_size(buf->buffer, 0)); > + trace_set_buffer_entries(buf, ring_buffer_capacity(buf->buffer, 0)); > } else { > - per_cpu_ptr(buf->data, cpu)->entries = ring_buffer_size(buf->buffer, cpu); > + per_cpu_ptr(buf->data, cpu)->entries = ring_buffer_capacity(buf->buffer, cpu); > } > } > > @@ -8476,7 +8476,7 @@ int allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, int > > /* Allocate the first page for all buffers */ > trace_set_buffer_entries(&tr->array_buffer, > - ring_buffer_size(tr->array_buffer.buffer, 0)); > + ring_buffer_capacity(tr->array_buffer.buffer, 0)); > > return 0; > } > > base-commit: df2908090cda368b01ff43709f51890076c56157 > -- > 2.55.0.979.g7e5102b832-goog >