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SubjectRe: [PATCH] tracing: Increase size of trace_marker_raw to max ring buffer entry
On Sat, 9 Dec 2023 17:57:16 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
>
> There's no reason to give an arbitrary limit to the size of a raw trace
> marker. Just let it be as big as the size that is allowed by the ring
> buffer itself.
>
> And there's also no reason to artificially break up the write to
> TRACE_BUF_SIZE, as that's not even used.

Looks good to me.

Reivewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thanks!

>
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> ---
> [
> Depends on: https://lore.kernel.org/linux-trace-kernel/20231209175003.63db40ab@gandalf.local.home/
> ]
> kernel/trace/trace.c | 13 ++++---------
> 1 file changed, 4 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index da837119a446..077b20e83e7c 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -7351,9 +7351,6 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
> return written;
> }
>
> -/* Limit it for now to 3K (including tag) */
> -#define RAW_DATA_MAX_SIZE (1024*3)
> -
> static ssize_t
> tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
> size_t cnt, loff_t *fpos)
> @@ -7375,18 +7372,16 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
> return -EINVAL;
>
> /* The marker must at least have a tag id */
> - if (cnt < sizeof(unsigned int) || cnt > RAW_DATA_MAX_SIZE)
> + if (cnt < sizeof(unsigned int))
> return -EINVAL;
>
> - if (cnt > TRACE_BUF_SIZE)
> - cnt = TRACE_BUF_SIZE;
> -
> - BUILD_BUG_ON(TRACE_BUF_SIZE >= PAGE_SIZE);
> -
> size = sizeof(*entry) + cnt;
> if (cnt < FAULT_SIZE_ID)
> size += FAULT_SIZE_ID - cnt;
>
> + if (size > ring_buffer_max_event_size(buffer))
> + return -EINVAL;
> +
> buffer = tr->array_buffer.buffer;
> event = __trace_buffer_lock_reserve(buffer, TRACE_RAW_DATA, size,
> tracing_gen_ctx());
> --
> 2.42.0
>


--
Masami Hiramatsu (Google) <mhiramat@kernel.org>

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