Re: [RFC v3 8/9] kmsg: add predefined _PID, _TID, _COMM keywords to kmsg* log dict

Hi Andy,

On Mon, 19 Oct 2015, Andy Lutomirski wrote:

On Mon, Oct 19, 2015 at 5:58 AM, Paul Osmialowski
[off-list ref] wrote:

quoted

From: Marcin Niesluchowski <redacted>

kmsg* devices write operation wrote no dict along with message
Due to usage of kmsg devices in userspace dict has been added
identifying pid, tid and comm of writing process.

Does this affect even the normal /dev/kmsg?

Yes.

quoted

-static int kmsg_sys_write(int minor, int level, const char *fmt, ...)
+static size_t set_kmsg_dict(char *buf)
+{
+       size_t len;
+
+       len = sprintf(buf, "_PID=%d", task_tgid_nr(current)) + 1;
+       len += sprintf(buf + len, "_TID=%d", task_pid_nr(current)) + 1;
+       memcpy(buf + len, "_COMM=", 6);
+       len += 6;
+       get_task_comm(buf + len, current);
+       while (buf[len] != '\0')
+               len++;

len += strlen(buf); ?

Is it obvious for some reason that this doesn't overflow buf?

KMSG_DICT_MAX_LEN sets architecture-intepentent max size.

Why is task_pid_nr acceptable here?  Isn't this intended for use in namespaces?

task_tgid_nr - process id (pid as seen in userspace),
task_pid_nr - thread id

Thanks,
Paul