Re: [PATCH 1/2] s390/dasd: Add __context_unsafe() attribute to various functions

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

On Thu, Aug 06, 2026 at 09:34:06AM -0700, Bart Van Assche wrote:
> On 8/6/26 6:00 AM, Heiko Carstens wrote:
> > diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
> > index bacf770c0e1f..b4dcef06edaa 100644
> > --- a/drivers/s390/block/dasd_eckd.c
> > +++ b/drivers/s390/block/dasd_eckd.c
> > @@ -1468,6 +1468,7 @@ static void dasd_eckd_path_available_action(struct dasd_device *device,
> >   }
> >   static void do_pe_handler_work(struct work_struct *work)
> > +__context_unsafe(/* Conditional locking */)
> >   {
> >   	struct pe_handler_work_data *data;
> >   	struct dasd_device *device;
> 
> __context_unsafe() should be avoided if there is a better solution.

Sure, I did that for other code, but this one is up to Stefan.

> For
> this driver I propose to make the following changes:
> - Change dasd_pe_handler_mutex into a semaphore. This driver locks this
>   mutex from one kernel thread and unlocks it from another kernel
>   thread. That's not allowed!

Yes, I did not realize that when adding those attributes, however that
was also reported by Sashiko.

> - Split the dasd_eckd_read_vol_info(), dasd_eckd_release(), ...
>   functions. Move the code between the mutex_lock() and mutex_unlock()
>   calls into a new function. Rework both functions such that the
>   mutex_lock() and mutex_unlock() calls end up in the same branch of an
>   if-statement.

Agreed, all for Stefan's todo list :)