Re: [PATCH v5 16/18] tracing/remotes: Add trace_remote cmdline options

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] User-controllable command-line arguments inappropriately trigger a WARN_ON().
--

--- Patch [16]: [PATCH v5 16/18] tracing/remotes: Add trace_remote cmdline options ---
commit 473129b2ec6ced6d4d23093ce86b83497f7202d2
Author: Vincent Donnefort <vdonnefort@google.com>

tracing/remotes: Add trace_remote cmdline options

This commit adds a trace_remote= boot command-line option to configure a
trace remote upon registration. It enables configuring various options like
buffer size, polling interval, and activating specific tracing events.

> diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c
> index b1c75666ab638..8764d0ed39097 100644
> --- a/kernel/trace/trace_remote.c
> +++ b/kernel/trace/trace_remote.c

[ ... ]

> @@ -1169,6 +1171,124 @@ static int poll_ms_show(struct seq_file *s, void *unused)

[ ... ]

> +static void trace_remote_apply_cmdline_opts(struct trace_remote *remote, char *cmdline)
> +{

[ ... ]

> +		} else if (!strncmp(opt, "buf_size=", 9)) {
> +			/* buf_size can only be applied if the buffer is unloaded */
> +			if (!WARN_ON(trace_remote_loaded(remote)))
> +				remote->trace_buffer_size = memparse(opt + 9, NULL);

[Severity: Medium]
Should this be a pr_warn() instead of a WARN_ON()?

If the bootloader passes multiple trace_remote= parameters, and an earlier
parameter enables events (which loads the buffer) before a later parameter
tries to set buf_size= for the same remote, this check will fail and emit a
warning.

Because WARN_ON() is used here, a simple typo or misordered boot command line 
will trigger a splat and cause a kernel panic during boot on any system 
configured with panic_on_warn.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260812161340.2417322-1-vdonnefort@google.com?part=16