Re: [PATCH v2 4/7] tracing: Add synthetic event error logging

From: Steven Rostedt
Date: Mon Oct 12 2020 - 18:04:44 EST


On Mon, 12 Oct 2020 15:18:06 -0500
Tom Zanussi <zanussi@xxxxxxxxxx> wrote:

> +static int cmdstr_append(char *buf, const char *str, int *remaining)
> +{
> + int len = strlen(str);
> +
> + if (len + 1 >= *remaining) {
> + synth_err(SYNTH_ERR_CMD_TOO_LONG, 0);
> + return -EINVAL;
> + }
> +
> + strcat(buf, str);
> + strcat(buf, " ");
> + *remaining -= len + 1;
> +
> + return 0;
> +}
> +
> +static int save_cmdstr(int argc, const char *name, const char **argv)
> +{
> + int i, ret, remaining = MAX_DYNEVENT_CMD_LEN;
> + char *buf;
> +
> + synth_err_clear();
> +
> + buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
> + ret = cmdstr_append(buf, name, &remaining);
> + if (ret) {
> + kfree(buf);
> + return ret;
> + }
> +
> + for (i = 0; i < argc; i++) {
> + ret = cmdstr_append(buf, argv[i], &remaining);
> + if (ret) {
> + kfree(buf);
> + return ret;
> + }
> + }
> +
> + last_cmd_set(buf);
> +
> + kfree(buf);
> +
> + return ret;
> +}
> +

Hmm, the above could easily be replaced with:

struct seq_buf s;

buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
if (!buf)
return -ENOMEM;

seq_buf_init(&s, buf, MAX_DYNEVENT_CMD_LEN);

seq_buf_puts(&s, name);

for (i = 0; i < argc; i++) {
seq_buf_putc(&s, ' ');
seq_buf_puts(&s, argv[i]);
}

if (!seq_buf_buffer_left(&s)) {
synth_err(SYNTH_ERR_CMD_TOO_LONG, 0);
kfree(buf);
return -EINVAL;
}
buf[s.len] = 0;
last_cmd_set(buf);

kfree(buf);
return 0;


-- Steve