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linux/include/xen/xenbus.h
Greg Kroah-Hartman d69d804845 driver core: have match() callback in struct bus_type take a const * 
In the match() callback, the struct device_driver * should not be
changed, so change the function callback to be a const *.  This is one
step of many towards making the driver core safe to have struct
device_driver in read-only memory.

Because the match() callback is in all busses, all busses are modified
to handle this properly.  This does entail switching some container_of()
calls to container_of_const() to properly handle the constant *.

For some busses, like PCI and USB and HV, the const * is cast away in
the match callback as those busses do want to modify those structures at
this point in time (they have a local lock in the driver structure.)
That will have to be changed in the future if they wish to have their
struct device * in read-only-memory.

Cc: Rafael J. Wysocki <rafael@kernel.org>
Reviewed-by: Alex Elder <elder@kernel.org>
Acked-by: Sumit Garg <sumit.garg@linaro.org>
Link: https://lore.kernel.org/r/2024070136-wrongdoer-busily-01e8@gregkh
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-07-03 15:16:54 +02:00

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/******************************************************************************
* xenbus.h
*
* Talks to Xen Store to figure out what devices we have.
*
* Copyright (C) 2005 Rusty Russell, IBM Corporation
* Copyright (C) 2005 XenSource Ltd.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation; or, when distributed
* separately from the Linux kernel or incorporated into other
* software packages, subject to the following license:
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this source file (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy, modify,
* merge, publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#ifndef _XEN_XENBUS_H
#define _XEN_XENBUS_H
#include <linux/device.h>
#include <linux/notifier.h>
#include <linux/mutex.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/completion.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/semaphore.h>
#include <xen/interface/xen.h>
#include <xen/interface/grant_table.h>
#include <xen/interface/io/xenbus.h>
#include <xen/interface/io/xs_wire.h>
#include <xen/interface/event_channel.h>
#define XENBUS_MAX_RING_GRANT_ORDER 4
#define XENBUS_MAX_RING_GRANTS (1U << XENBUS_MAX_RING_GRANT_ORDER)
/* Register callback to watch this node. */
struct xenbus_watch
{
struct list_head list;
/* Path being watched. */
const char *node;
unsigned int nr_pending;
/*
* Called just before enqueing new event while a spinlock is held.
* The event will be discarded if this callback returns false.
*/
bool (*will_handle)(struct xenbus_watch *,
const char *path, const char *token);
/* Callback (executed in a process context with no locks held). */
void (*callback)(struct xenbus_watch *,
const char *path, const char *token);
};
/* A xenbus device. */
struct xenbus_device {
const char *devicetype;
const char *nodename;
const char *otherend;
int otherend_id;
struct xenbus_watch otherend_watch;
struct device dev;
enum xenbus_state state;
struct completion down;
struct work_struct work;
struct semaphore reclaim_sem;
/* Event channel based statistics and settings. */
atomic_t event_channels;
atomic_t events;
atomic_t spurious_events;
atomic_t jiffies_eoi_delayed;
unsigned int spurious_threshold;
};
#define to_xenbus_device(__dev) container_of_const(__dev, struct xenbus_device, dev)
struct xenbus_device_id
{
/* .../device/<device_type>/<identifier> */
char devicetype[32]; /* General class of device. */
};
/* A xenbus driver. */
struct xenbus_driver {
const char *name; /* defaults to ids[0].devicetype */
const struct xenbus_device_id *ids;
bool allow_rebind; /* avoid setting xenstore closed during remove */
bool not_essential; /* is not mandatory for boot progress */
int (*probe)(struct xenbus_device *dev,
const struct xenbus_device_id *id);
void (*otherend_changed)(struct xenbus_device *dev,
enum xenbus_state backend_state);
void (*remove)(struct xenbus_device *dev);
int (*suspend)(struct xenbus_device *dev);
int (*resume)(struct xenbus_device *dev);
int (*uevent)(const struct xenbus_device *, struct kobj_uevent_env *);
struct device_driver driver;
int (*read_otherend_details)(struct xenbus_device *dev);
int (*is_ready)(struct xenbus_device *dev);
void (*reclaim_memory)(struct xenbus_device *dev);
};
#define to_xenbus_driver(__drv) container_of_const(__drv, struct xenbus_driver, driver)
int __must_check __xenbus_register_frontend(struct xenbus_driver *drv,
struct module *owner,
const char *mod_name);
int __must_check __xenbus_register_backend(struct xenbus_driver *drv,
struct module *owner,
const char *mod_name);
#define xenbus_register_frontend(drv) \
__xenbus_register_frontend(drv, THIS_MODULE, KBUILD_MODNAME)
#define xenbus_register_backend(drv) \
__xenbus_register_backend(drv, THIS_MODULE, KBUILD_MODNAME)
void xenbus_unregister_driver(struct xenbus_driver *drv);
struct xenbus_transaction
{
u32 id;
};
/* Nil transaction ID. */
#define XBT_NIL ((struct xenbus_transaction) { 0 })
char **xenbus_directory(struct xenbus_transaction t,
const char *dir, const char *node, unsigned int *num);
void *xenbus_read(struct xenbus_transaction t,
const char *dir, const char *node, unsigned int *len);
int xenbus_write(struct xenbus_transaction t,
const char *dir, const char *node, const char *string);
int xenbus_mkdir(struct xenbus_transaction t,
const char *dir, const char *node);
int xenbus_exists(struct xenbus_transaction t,
const char *dir, const char *node);
int xenbus_rm(struct xenbus_transaction t, const char *dir, const char *node);
int xenbus_transaction_start(struct xenbus_transaction *t);
int xenbus_transaction_end(struct xenbus_transaction t, int abort);
/* Single read and scanf: returns -errno or num scanned if > 0. */
__scanf(4, 5)
int xenbus_scanf(struct xenbus_transaction t,
const char *dir, const char *node, const char *fmt, ...);
/* Read an (optional) unsigned value. */
unsigned int xenbus_read_unsigned(const char *dir, const char *node,
unsigned int default_val);
/* Single printf and write: returns -errno or 0. */
__printf(4, 5)
int xenbus_printf(struct xenbus_transaction t,
const char *dir, const char *node, const char *fmt, ...);
/* Generic read function: NULL-terminated triples of name,
* sprintf-style type string, and pointer. Returns 0 or errno.*/
int xenbus_gather(struct xenbus_transaction t, const char *dir, ...);
/* notifer routines for when the xenstore comes up */
extern int xenstored_ready;
int register_xenstore_notifier(struct notifier_block *nb);
void unregister_xenstore_notifier(struct notifier_block *nb);
int register_xenbus_watch(struct xenbus_watch *watch);
void unregister_xenbus_watch(struct xenbus_watch *watch);
void xs_suspend(void);
void xs_resume(void);
void xs_suspend_cancel(void);
struct work_struct;
#define XENBUS_IS_ERR_READ(str) ({ \
if (!IS_ERR(str) && strlen(str) == 0) { \
kfree(str); \
str = ERR_PTR(-ERANGE); \
} \
IS_ERR(str); \
})
#define XENBUS_EXIST_ERR(err) ((err) == -ENOENT || (err) == -ERANGE)
int xenbus_watch_path(struct xenbus_device *dev, const char *path,
struct xenbus_watch *watch,
bool (*will_handle)(struct xenbus_watch *,
const char *, const char *),
void (*callback)(struct xenbus_watch *,
const char *, const char *));
__printf(5, 6)
int xenbus_watch_pathfmt(struct xenbus_device *dev, struct xenbus_watch *watch,
bool (*will_handle)(struct xenbus_watch *,
const char *, const char *),
void (*callback)(struct xenbus_watch *,
const char *, const char *),
const char *pathfmt, ...);
int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state new_state);
int xenbus_setup_ring(struct xenbus_device *dev, gfp_t gfp, void **vaddr,
unsigned int nr_pages, grant_ref_t *grefs);
void xenbus_teardown_ring(void **vaddr, unsigned int nr_pages,
grant_ref_t *grefs);
int xenbus_map_ring_valloc(struct xenbus_device *dev, grant_ref_t *gnt_refs,
unsigned int nr_grefs, void **vaddr);
int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr);
int xenbus_alloc_evtchn(struct xenbus_device *dev, evtchn_port_t *port);
int xenbus_free_evtchn(struct xenbus_device *dev, evtchn_port_t port);
enum xenbus_state xenbus_read_driver_state(const char *path);
__printf(3, 4)
void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, ...);
__printf(3, 4)
void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, ...);
const char *xenbus_strstate(enum xenbus_state state);
int xenbus_dev_is_online(struct xenbus_device *dev);
int xenbus_frontend_closed(struct xenbus_device *dev);
extern const struct file_operations xen_xenbus_fops;
extern struct xenstore_domain_interface *xen_store_interface;
extern int xen_store_evtchn;
#endif /* _XEN_XENBUS_H */
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