On Oct 18, 2024, at 2:49 AM, Simon Horman horms@kernel.org wrote:
On Thu, Oct 17, 2024 at 11:14:33AM -0700, Anjali Kulkarni wrote:
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