Re: [PATCH v2 2/3] s390/pci: Rework__zpci_event_availability() to remove conditional locking

[Heiko Carstens <hca@linux.ibm.com>]

On Wed, Aug 05, 2026 at 01:32:10PM +0200, Niklas Schnelle wrote:
> On Mon, 2026-08-03 at 16:29 +0200, Heiko Carstens wrote:
> > Clang's compiler based static context analysis does not work with locks
> > that are conditionally taken like in __zpci_event_availability():
> > 
> > arch/s390/pci/pci_event.c:402:10: warning: mutex 'get_zdev_by_fid(ccdf->fid).state_lock'
> >   is not held on every path through here [-Wthread-safety-analysis]
> > 
> > Given that code which takes locks conditionally can be considered
> > suboptimal rework __zpci_event_availability() to get rid of this.
> > 
> > Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
> > ---
> >  arch/s390/pci/pci_event.c | 108 +++++++++++++++++++-------------------
> >  1 file changed, 53 insertions(+), 55 deletions(-)

...

> Personally I think I'd put the 0x0306 and each of the two switches in
> helper functions to improve readability as this is getting awfully
> long. Maybe something like zpci_event_avail_any_device() (0x0306),
> zpci_event_avail_new_device() and zpci_event_avail_existing_device().
> 
> If you prefer and since I'm doing a follow up for the missing locking
> in zpci_reserved_devices() I can also do that in a separate patch. Also
> just to clarify Sashiko is right in that the missing locking is a pre-
> existing issue as the state_lock was already not taken in that case,
> it's just more obvious now.
> 
> Either way, functionality looks good to me so feel free to add:
> 
> Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>

Thanks, I'll address the two nits for patch 1 and 2, and will send a
new version. However I prefer if you do additional code refactoring
with addon patches, so the result looks exactly like you want it.
Otherwise we will go back and forth :)