linux-kernel - Re: [PATCH v10 13/30] tracing: Introduce simple_ring

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Message-ID: <20260128181847.222ea802@gandalf.local.home>
Date: Wed, 28 Jan 2026 18:18:47 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Vincent Donnefort <vdonnefort@...gle.com>
Cc: mhiramat@...nel.org, mathieu.desnoyers@...icios.com,
 linux-trace-kernel@...r.kernel.org, maz@...nel.org, oliver.upton@...ux.dev,
 joey.gouly@....com, suzuki.poulose@....com, yuzenghui@...wei.com,
 kvmarm@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
 jstultz@...gle.com, qperret@...gle.com, will@...nel.org,
 aneesh.kumar@...nel.org, kernel-team@...roid.com,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 13/30] tracing: Introduce simple_ring_buffer

On Mon, 26 Jan 2026 10:44:02 +0000
Vincent Donnefort <vdonnefort@...gle.com> wrote:

> +
> +/**
> + * simple_ring_buffer_init - Init @cpu_buffer based on @desc
> + *
> + * @cpu_buffer:	A simple_rb_per_cpu buffer to init, allocated by the caller.
> + * @bpages:	Array of simple_buffer_pages, with as many elements as @desc->nr_page_va
> + * @desc:	A ring_buffer_desc
> + *
> + * Returns: 0 on success or -EINVAL if the content of @desc is invalid
> + */

Again, kerneldoc goes with the function and not the prototype.

Especially helps with review, as I like to see the kerneldoc what reading
the function.

-- Steve

> +int simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, struct simple_buffer_page *bpages,
> +			    const struct ring_buffer_desc *desc);
> +
> +/**
> + * simple_ring_buffer_unload - Prepare @cpu_buffer for deletion
> + *
> + * @cpu_buffer:	A simple_rb_per_cpu that will be deleted.
> + */
> +void simple_ring_buffer_unload(struct simple_rb_per_cpu *cpu_buffer);
> +
> +/**
> + * simple_ring_buffer_reserve - Reserve an entry in @cpu_buffer
> + *
> + * @cpu_buffer:	A simple_rb_per_cpu
> + * @length:	Size of the entry in bytes
> + * @timestamp:	Timestamp of the entry
> + *
> + * Returns the address of the entry where to write data or NULL
> + */
> +void *simple_ring_buffer_reserve(struct simple_rb_per_cpu *cpu_buffer, unsigned long length,
> +				 u64 timestamp);
> +
> +/**
> + * simple_ring_buffer_commit - Commit the entry reserved with simple_ring_buffer_reserve()
> + *
> + * @cpu_buffer:	The simple_rb_per_cpu where the entry has been reserved
> + */
> +void simple_ring_buffer_commit(struct simple_rb_per_cpu *cpu_buffer);
> +
> +/**
> + * simple_ring_buffer_enable_tracing - Enable or disable writing to @cpu_buffer
> + *
> + * @cpu_buffer: A simple_rb_per_cpu
> + * @enable:	True to enable tracing, False to disable it
> + *
> + * Returns 0 on success or -ENODEV if @cpu_buffer was unloaded
> + */
> +int simple_ring_buffer_enable_tracing(struct simple_rb_per_cpu *cpu_buffer, bool enable);
> +
> +/**
> + * simple_ring_buffer_reset - Reset @cpu_buffer
> + *
> + * @cpu_buffer: A simple_rb_per_cpu
> + *
> + * This will not clear the content of the data, only reset counters and pointers
> + *
> + * Returns 0 on success or -ENODEV if @cpu_buffer was unloaded.
> + */
> +int simple_ring_buffer_reset(struct simple_rb_per_cpu *cpu_buffer);
> +
> +/**
> + * simple_ring_buffer_swap_reader_page - Swap ring-buffer head with the reader
> + *
> + * This function enables consuming reading. It ensures the current head page will not be overwritten
> + * and can be safely read.
> + *
> + * @cpu_buffer: A simple_rb_per_cpu
> + *
> + * Returns 0 on success, -ENODEV if @cpu_buffer was unloaded or -EBUSY if we failed to catch the
> + * head page.
> + */
> +int simple_ring_buffer_swap_reader_page(struct simple_rb_per_cpu *cpu_buffer);
> +
> +#endif