From: Jason Gunthorpe <jgg@nvidia.com>
To: David Hildenbrand <david@redhat.com>
Cc: Tony Krowiak <akrowiak@linux.ibm.com>,
linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
borntraeger@de.ibm.com, cohuck@redhat.com,
pasic@linux.vnet.ibm.com, jjherne@linux.ibm.com,
alex.williamson@redhat.com, kwankhede@nvidia.com,
frankja@linux.ibm.com, imbrenda@linux.ibm.com, hca@linux.ibm.com
Subject: Re: [PATCH 2/3] s390/vfio-ap: introduce two new r/w locks to replace wait_queue_head_t
Date: Fri, 11 Jun 2021 14:41:50 -0300 [thread overview]
Message-ID: <20210611174150.GX1002214@nvidia.com> (raw)
In-Reply-To: <7ed059b0-5d58-eeec-167c-280917b47c00@redhat.com>
On Fri, Jun 11, 2021 at 07:11:50PM +0200, David Hildenbrand wrote:
> > Also, not convinced down_write_trylock() is appropriate from a sysfs
> > callback, it should block and wait, surely? Otherwise userspace gets
> > random racy failures depending on what the kernel is doing??
>
> It might we worth exploring lock_device_hotplug_sysfs() which does a
>
> "return restart_syscall()" with some delay.
The ideal design from a sysfs should be a single
down_write_killable().
restart_syscall will just create a weird spinlock that is hopefully
unlikely to spin :\
Jason
next prev parent reply other threads:[~2021-06-11 17:41 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-09 22:46 [PATCH 0/3] s390/vfio-ap: refactor mdev remove callback and locks Tony Krowiak
2021-06-09 22:46 ` [PATCH 1/3] s390/vfio-ap: clean up mdev resources when remove callback invoked Tony Krowiak
2021-06-11 16:48 ` Jason Gunthorpe
2021-06-14 17:29 ` Tony Krowiak
2021-06-15 7:43 ` Christian Borntraeger
2021-06-09 22:46 ` [PATCH 2/3] s390/vfio-ap: introduce two new r/w locks to replace wait_queue_head_t Tony Krowiak
2021-06-11 17:05 ` Jason Gunthorpe
2021-06-11 17:11 ` David Hildenbrand
2021-06-11 17:41 ` Jason Gunthorpe [this message]
2021-06-09 22:46 ` [PATCH 3/3] s390/vfio-ap: r/w lock for PQAP interception handler function pointer Tony Krowiak
2021-06-11 17:06 ` Jason Gunthorpe
2021-06-15 8:55 ` Christian Borntraeger
2021-06-15 18:08 ` Tony Krowiak
2021-06-15 18:55 ` Tony Krowiak
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