linux-kernel - Re: [PATCH RFC 20/39] xen-blkback: module

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Date:   Mon, 25 Feb 2019 13:57:19 -0500
From:   Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:     Joao Martins <joao.m.martins@...cle.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        xen-devel@...ts.xenproject.org,
        Ankur Arora <ankur.a.arora@...cle.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Roger Pau Monné <roger.pau@...rix.com>
Subject: Re: [PATCH RFC 20/39] xen-blkback: module_exit support

On Wed, Feb 20, 2019 at 08:15:50PM +0000, Joao Martins wrote:
> 
> Implement module_exit to allow users to do module unload of blkback.
> We prevent users from module unload whenever there are still interfaces
> allocated, in other words, do module_get on xen_blkif_alloc() and
> module_put on xen_blkif_free().

This patch looks like it can go now in right?

> 
> Signed-off-by: Joao Martins <joao.m.martins@...cle.com>
> ---
>  drivers/block/xen-blkback/blkback.c |  8 ++++++++
>  drivers/block/xen-blkback/common.h  |  2 ++
>  drivers/block/xen-blkback/xenbus.c  | 14 ++++++++++++++
>  3 files changed, 24 insertions(+)
> 
> diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
> index fd1e19f1a49f..d51d88be88e1 100644
> --- a/drivers/block/xen-blkback/blkback.c
> +++ b/drivers/block/xen-blkback/blkback.c
> @@ -1504,5 +1504,13 @@ static int __init xen_blkif_init(void)
>  
>  module_init(xen_blkif_init);
>  
> +static void __exit xen_blkif_exit(void)
> +{
> +	xen_blkif_interface_exit();
> +	xen_blkif_xenbus_exit();
> +}
> +
> +module_exit(xen_blkif_exit);
> +
>  MODULE_LICENSE("Dual BSD/GPL");
>  MODULE_ALIAS("xen-backend:vbd");
> diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
> index 1d3002d773f7..3415c558e115 100644
> --- a/drivers/block/xen-blkback/common.h
> +++ b/drivers/block/xen-blkback/common.h
> @@ -376,8 +376,10 @@ struct phys_req {
>  	blkif_sector_t		sector_number;
>  };
>  int xen_blkif_interface_init(void);
> +void xen_blkif_interface_exit(void);
>  
>  int xen_blkif_xenbus_init(void);
> +void xen_blkif_xenbus_exit(void);
>  
>  irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
>  int xen_blkif_schedule(void *arg);
> diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
> index a4bc74e72c39..424e2efebe85 100644
> --- a/drivers/block/xen-blkback/xenbus.c
> +++ b/drivers/block/xen-blkback/xenbus.c
> @@ -181,6 +181,8 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
>  	init_completion(&blkif->drain_complete);
>  	INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
>  
> +	__module_get(THIS_MODULE);
> +
>  	return blkif;
>  }
>  
> @@ -328,6 +330,8 @@ static void xen_blkif_free(struct xen_blkif *blkif)
>  
>  	/* Make sure everything is drained before shutting down */
>  	kmem_cache_free(xen_blkif_cachep, blkif);
> +
> +	module_put(THIS_MODULE);
>  }
>  
>  int __init xen_blkif_interface_init(void)
> @@ -341,6 +345,11 @@ int __init xen_blkif_interface_init(void)
>  	return 0;
>  }
>  
> +void xen_blkif_interface_exit(void)
> +{
> +	kmem_cache_destroy(xen_blkif_cachep);
> +}
> +
>  /*
>   *  sysfs interface for VBD I/O requests
>   */
> @@ -1115,3 +1124,8 @@ int xen_blkif_xenbus_init(void)
>  {
>  	return xenbus_register_backend(&xen_blkbk_driver);
>  }
> +
> +void xen_blkif_xenbus_exit(void)
> +{
> +	xenbus_unregister_driver(&xen_blkbk_driver);
> +}
> -- 
> 2.11.0
>