If xen_backend_device_create() fails to instantiate a device, the XenBus code will just keep trying over and over again each time the bus is re-enumerated, as long as the backend appears online and in XenbusStateInitialising. The only thing which prevents the XenBus code from recreating duplicates of devices which already exist, is the fact that xen_device_realize() sets the backend state to XenbusStateInitWait. If the attempt to create the device doesn't get *that* far, that's when it will keep getting retried. My first thought was to handle errors by setting the backend state to XenbusStateClosed, but that doesn't work for XenConsole which wants to *ignore* any device of type != "ioemu" completely. So, make xen_backend_device_create() *keep* the XenBackendInstance for a failed device, and provide a new xen_backend_exists() function to allow xen_bus_type_enumerate() to check whether one already exists before creating a new one. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Paul Durrant <paul@xen.org>
		
			
				
	
	
		
			42 lines
		
	
	
		
			1.4 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			42 lines
		
	
	
		
			1.4 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/*
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 * Copyright (c) 2018  Citrix Systems Inc.
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 *
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 * This work is licensed under the terms of the GNU GPL, version 2 or later.
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 * See the COPYING file in the top-level directory.
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 */
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#ifndef HW_XEN_BACKEND_H
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#define HW_XEN_BACKEND_H
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#include "hw/xen/xen-bus.h"
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typedef struct XenBackendInstance XenBackendInstance;
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typedef void (*XenBackendDeviceCreate)(XenBackendInstance *backend,
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                                       QDict *opts, Error **errp);
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typedef void (*XenBackendDeviceDestroy)(XenBackendInstance *backend,
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                                        Error **errp);
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typedef struct XenBackendInfo {
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    const char *type;
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    XenBackendDeviceCreate create;
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    XenBackendDeviceDestroy destroy;
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} XenBackendInfo;
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XenBus *xen_backend_get_bus(XenBackendInstance *backend);
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const char *xen_backend_get_name(XenBackendInstance *backend);
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void xen_backend_set_device(XenBackendInstance *backend,
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                            XenDevice *xendevice);
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XenDevice *xen_backend_get_device(XenBackendInstance *backend);
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void xen_backend_register(const XenBackendInfo *info);
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const char **xen_backend_get_types(unsigned int *nr);
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bool xen_backend_exists(const char *type, const char *name);
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void xen_backend_device_create(XenBus *xenbus, const char *type,
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                               const char *name, QDict *opts, Error **errp);
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bool xen_backend_try_device_destroy(XenDevice *xendev, Error **errp);
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#endif /* HW_XEN_BACKEND_H */
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