Re: [PATCH v6 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] The `dump_on_panic` command-line option sets `remote->panic_on = true` but fails to dynamically register the panic handler if the trace buffer is already loaded.
--

--- Patch [16]: [PATCH v6 16/18] tracing/remotes: Add trace_remote cmdline options ---
commit 16551de261e3bdeffe51c1a5227c6a115ddbe725
Author: Vincent Donnefort <vdonnefort@google.com>

tracing/remotes: Add trace_remote cmdline options
    
This commit introduces command-line options for trace remotes, allowing
configuration of features like dump_on_panic, dmesg, buf_size, and poll,
as well as enabling specific trace events automatically on boot.

> diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c
> index 204d5bef7a8c4..34847463d9e43 100644
> --- a/kernel/trace/trace_remote.c
> +++ b/kernel/trace/trace_remote.c

[ ... ]

> @@ -1170,6 +1172,126 @@ static int poll_ms_show(struct seq_file *s, void *unused)
> +static void trace_remote_apply_cmdline_opts(struct trace_remote *remote, char *cmdline)
> +{
> +	bool dmesg_on = false;
> +	char *opt;
> +	int ret;
> +
> +	while ((opt = strsep(&cmdline, "^"))) {
> +		if (!*opt)
> +			continue;
> +
> +		if (!strcmp(opt, "dump_on_panic")) {
> +			remote->panic_on = true;

[Severity: Medium]
If the trace remote was configured across multiple command line arguments, and
an earlier argument already enabled events (which loads the trace buffer via
trace_remote_enable_tracing()), will setting remote->panic_on = true here
fail to register the panic notifier?

Since this doesn't call trace_remote_panic_load() if the buffer is already
loaded, it appears the panic handler might never be registered under this
configuration pattern.

> +		} else if (!strcmp(opt, "dmesg")) {
> +			dmesg_on = true;
> +		} else if (!strncmp(opt, "buf_size=", 9)) {
> +			/* buf_size can only be applied if the buffer is unloaded */
> +			if (trace_remote_loaded(remote))
> +				pr_warn("Cannot apply buf_size after events are enabled\n");
> +			else
> +				remote->trace_buffer_size = memparse(opt + 9, NULL);

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260817135517.3919534-1-vdonnefort@google.com?part=16