Re: [PATCH] eal: add worker threads cleanup in rte_eal_cleanup()

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 13 Jan 2025 05:13:01 +0000
Gagandeep Singh <G.Singh@nxp.com> wrote:

> Hi,
> 
> > -----Original Message-----
> > From: Stephen Hemminger <stephen@networkplumber.org>
> > Sent: Friday, January 10, 2025 10:49 PM
> > To: Gagandeep Singh <G.Singh@nxp.com>
> > Cc: dev@dpdk.org
> > Subject: Re: [PATCH] eal: add worker threads cleanup in rte_eal_cleanup()
> > 
> > On Fri, 10 Jan 2025 12:17:17 +0530
> > Gagandeep Singh <g.singh@nxp.com> wrote:
> >   
> > > This patch introduces a worker thread cleanup function in the EAL
> > > library, ensuring proper termination of created pthreads and
> > > invocation of registered pthread destructors.
> > > This guarantees the correct cleanup of thread-specific resources, used
> > > by drivers or applications.
> > >
> > > Signed-off-by: Gagandeep Singh <g.singh@nxp.com>
> > > ---  
> > 
> > What problem is this trying to solve?
> > 
> > Canceling threads sends signals and can be problematic.
> > Many of the operations done in drivers are not signal safe.  
> 
> To ensure the proper cleanup of thread-specific resources, the DPAA driver initializes pthread-specific destructors using pthread_key_create(). These destructors are executed only when a thread terminates or the key is deleted. However, since threads are not terminated when the application is killed, these destructors are not executed, resulting in resource leaks.
> To address this issue, we propose adding thread termination code to rte_eal_cleanup() to ensure that threads are properly terminated, thereby triggering the execution of pthread-specific destructors
> 
> Any alternate suggestion in case pthread_cancel is not a better solution? We can add pthread join timeout to avoid blocking on thread stuck or
> May be any way to call pthread_exit?

The DPAA driver is the problem here. It should not be using pthread_key.
Other drivers don't do this. Other drivers do setup on probe and cleanup on close.

An application doing a clean shutdown should do what existing testpmd, l3fwd, do
	- wait for worker threads to go idle
	- stop all ports
	- close all ports
	- call eal cleanup

If DPAA driver needs pthread_key it should handling that in the close.
But it really should be using DPDK thread local storage for this.