[PATCH 1/1] eal: correct memory ordering in MCS lock

[Stephen Hemminger]

On Mon, 3 Nov 2025 18:06:05 +0000
Konstantin Ananyev <konstantin.ananyev at huawei.com> wrote:

> > 
> > On 11/3/25 11:07, Stephen Hemminger wrote:  
> > > On Mon, 3 Nov 2025 09:12:39 -0600
> > > Wathsala Vithanage <wathsala.vithanage at arm.com> wrote:
> > >  
> > >> MCS lock is broken, it's just a matter of time it will run into a deadlock.
> > >>
> > >> drivers/dma/cnxk is a user of MCS lock.  
> > > I am surprised that a driver would use mcslock.
> > > MCSlock is targeted at case of large number of CPU's with lots of contention.
> > > It will likely be slower than spinlock or ticketlock for the use case of driver.  
> > It appears in |drivers/dma/cnxk/cnxk_dmadev_fp.c|, perhaps the
> > maintainer can clarify.
> >   
> 
> If MCS lock is really broken, it needs to be fixed anyway.
> It might be used by other third-party libs/apps that do use on DPDK.

100% agree it must be fixed.
It would be good to have test or static analysis tool that could validate all the lock types.