Re: [PATCH net-next v5 0/3] Threads support in proc connector

On Oct 18, 2024, at 2:49 AM, Simon Horman [off-list ref] wrote:

On Thu, Oct 17, 2024 at 11:14:33AM -0700, Anjali Kulkarni wrote:

quoted

Recently we committed a fix to allow processes to receive notifications for
non-zero exits via the process connector module. Commit is a4c9a56e6a2c.

However, for threads, when it does a pthread_exit(&exit_status) call, the
kernel is not aware of the exit status with which pthread_exit is called.
It is sent by child thread to the parent process, if it is waiting in
pthread_join(). Hence, for a thread exiting abnormally, kernel cannot
send notifications to any listening processes.

The exception to this is if the thread is sent a signal which it has not
handled, and dies along with it's process as a result; for eg. SIGSEGV or
SIGKILL. In this case, kernel is aware of the non-zero exit and sends a
notification for it.

For our use case, we cannot have parent wait in pthread_join, one of the
main reasons for this being that we do not want to track normal
pthread_exit(), which could be a very large number. We only want to be
notified of any abnormal exits. Hence, threads are created with
pthread_attr_t set to PTHREAD_CREATE_DETACHED.

To fix this problem, we add a new type PROC_CN_MCAST_NOTIFY to proc connector
API, which allows a thread to send it's exit status to kernel either when
it needs to call pthread_exit() with non-zero value to indicate some
error or from signal handler before pthread_exit().

We also need to filter packets with non-zero exit notifications futher
based on instances, which can be identified by task names. Hence, added a
comm field to the packet's struct proc_event, in which task->comm is
stored.

As it seems that there will be another revision anyway,
please run this patch-set through checkpatch with the following arguments.

./scripts/checkpatch.pl --strict --max-line-length=80

And please fix warnings about alignment and line length.
But please do so in such a way that doesn't reduce readability,
e.g. don't split strings over multiple lines.

Ok thanks, will do. 

Anjali