Commit b620ecbd authored by Alex Williamson's avatar Alex Williamson
Browse files

vfio: Introduce interface to flush virqfd inject workqueue 



In order to synchronize changes that can affect the thread callback,
introduce an interface to force a flush of the inject workqueue.  The
irqfd pointer is only valid under spinlock, but the workqueue cannot
be flushed under spinlock.  Therefore the flush work for the irqfd is
queued under spinlock.  The vfio_irqfd_cleanup_wq workqueue is re-used
for queuing this work such that flushing the workqueue is also ordered
relative to shutdown.

Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Reviewed-by: default avatarReinette Chatre <reinette.chatre@intel.com>
Reviewed-by: default avatarEric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20240308230557.805580-4-alex.williamson@redhat.com


Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent 810cd4bb

drivers/vfio/virqfd.c

+21 −0
Original line number Diff line number Diff line
@@ -101,6 +101,13 @@ static void virqfd_inject(struct work_struct *work) 
		virqfd->thread(virqfd->opaque, virqfd->data);

}



static void virqfd_flush_inject(struct work_struct *work)

{

	struct virqfd *virqfd = container_of(work, struct virqfd, flush_inject);



	flush_work(&virqfd->inject);

}



int vfio_virqfd_enable(void *opaque,

		       int (*handler)(void *, void *),

		       void (*thread)(void *, void *),
@@ -124,6 +131,7 @@ int vfio_virqfd_enable(void *opaque, 


	INIT_WORK(&virqfd->shutdown, virqfd_shutdown);

	INIT_WORK(&virqfd->inject, virqfd_inject);

	INIT_WORK(&virqfd->flush_inject, virqfd_flush_inject);



	irqfd = fdget(fd);

	if (!irqfd.file) {
@@ -213,3 +221,16 @@ void vfio_virqfd_disable(struct virqfd **pvirqfd) 
	flush_workqueue(vfio_irqfd_cleanup_wq);

}

EXPORT_SYMBOL_GPL(vfio_virqfd_disable);



void vfio_virqfd_flush_thread(struct virqfd **pvirqfd)

{

	unsigned long flags;



	spin_lock_irqsave(&virqfd_lock, flags);

	if (*pvirqfd && (*pvirqfd)->thread)

		queue_work(vfio_irqfd_cleanup_wq, &(*pvirqfd)->flush_inject);

	spin_unlock_irqrestore(&virqfd_lock, flags);



	flush_workqueue(vfio_irqfd_cleanup_wq);

}

EXPORT_SYMBOL_GPL(vfio_virqfd_flush_thread);

include/linux/vfio.h

+2 −0
Original line number Diff line number Diff line
@@ -356,6 +356,7 @@ struct virqfd { 
	wait_queue_entry_t		wait;

	poll_table		pt;

	struct work_struct	shutdown;

	struct work_struct	flush_inject;

	struct virqfd		**pvirqfd;

};
@@ -363,5 +364,6 @@ int vfio_virqfd_enable(void *opaque, int (*handler)(void *, void *), 
		       void (*thread)(void *, void *), void *data,

		       struct virqfd **pvirqfd, int fd);

void vfio_virqfd_disable(struct virqfd **pvirqfd);

void vfio_virqfd_flush_thread(struct virqfd **pvirqfd);



#endif /* VFIO_H */