Rename struct device to struct _device

types.h defines device_t as a typedef of struct device *.  struct device
is defined in subr_bus.c and almost all of the kernel uses device_t.
The LinuxKPI also defines a struct device, so type confusion can occur.

This causes bugs and ambiguity for debugging tools.  Rename the FreeBSD
struct device to struct _device.

Reviewed by:	gbe (man pages)
Reviewed by:	rpokala, imp, jhb
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D29676

share/man/man9/device.9

@@ -35,7 +35,7 @@
 .Nm device
 .Nd an abstract representation of a device
 .Sh SYNOPSIS
-.Vt typedef struct device *device_t ;
+.Vt typedef struct _device *device_t ;
 .Sh DESCRIPTION
 The device object represents a piece of hardware attached to the
 system such as an expansion card, the bus which that card is plugged

share/man/man9/rman.9

@@ -88,12 +88,12 @@
 .Ft "struct resource *"
 .Fo rman_reserve_resource
 .Fa "struct rman *rm" "rman_res_t start" "rman_res_t end" "rman_res_t count"
-.Fa "u_int flags" "struct device *dev"
+.Fa "u_int flags" "device_t dev"
 .Fc
 .Ft "struct resource *"
 .Fo rman_reserve_resource_bound
 .Fa "struct rman *rm" "rman_res_t start" "rman_res_t end" "rman_res_t count"
-.Fa "rman_res_t bound" "u_int flags" "struct device *dev"
+.Fa "rman_res_t bound" "u_int flags" "device_t dev"
 .Fc
 .Ft uint32_t
 .Fn rman_make_alignment_flags "uint32_t size"
@@ -101,7 +101,7 @@
 .Fn rman_get_start "struct resource *r"
 .Ft rman_res_t
 .Fn rman_get_end "struct resource *r"
-.Ft "struct device *"
+.Ft "device_t"
 .Fn rman_get_device "struct resource *r"
 .Ft rman_res_t
 .Fn rman_get_size "struct resource *r"

sys/kern/subr_bus.c

@@ -95,7 +95,7 @@ struct driverlink {
  */
 typedef TAILQ_HEAD(devclass_list, devclass) devclass_list_t;
 typedef TAILQ_HEAD(driver_list, driverlink) driver_list_t;
-typedef TAILQ_HEAD(device_list, device) device_list_t;
+typedef TAILQ_HEAD(device_list, _device) device_list_t;
 
 struct devclass {
 	TAILQ_ENTRY(devclass) link;
@@ -112,9 +112,12 @@ struct devclass {
 };
 
 /**
- * @brief Implementation of device.
+ * @brief Implementation of _device.
+ *
+ * The structure is named "_device" instead of "device" to avoid type confusion
+ * caused by other subsystems defining a (struct device).
  */
-struct device {
+struct _device {
 	/*
 	 * A device is a kernel object. The first field must be the
 	 * current ops table for the object.
@@ -124,8 +127,8 @@ struct device {
 	/*
 	 * Device hierarchy.
 	 */
-	TAILQ_ENTRY(device)	link;	/**< list of devices in parent */
+	TAILQ_ENTRY(_device)	link;	/**< list of devices in parent */
-	TAILQ_ENTRY(device)	devlink; /**< global device list membership */
+	TAILQ_ENTRY(_device)	devlink; /**< global device list membership */
 	device_t	parent;		/**< parent of this device  */
 	device_list_t	children;	/**< list of child devices */
 
@@ -853,7 +856,7 @@ devctl_safe_quote_sb(struct sbuf *sb, const char *src)
 
 /* End of /dev/devctl code */
 
-static TAILQ_HEAD(,device)	bus_data_devices;
+static struct device_list bus_data_devices;
 static int bus_data_generation = 1;
 
 static kobj_method_t null_methods[] = {

sys/powerpc/include/bus_dma.h

@@ -33,8 +33,6 @@
 #include <sys/bus_dma.h>
 #include <sys/bus_dma_internal.h>
 
-struct device;
+int bus_dma_tag_set_iommu(bus_dma_tag_t, device_t iommu, void *cookie);
-
-int bus_dma_tag_set_iommu(bus_dma_tag_t, struct device *iommu, void *cookie);
 
 #endif /* _POWERPC_BUS_DMA_H_ */

sys/sys/pcpu.h

@@ -187,7 +187,7 @@ struct pcpu {
 	STAILQ_ENTRY(pcpu) pc_allcpu;
 	struct lock_list_entry *pc_spinlocks;
 	long		pc_cp_time[CPUSTATES];	/* statclock ticks */
-	struct device	*pc_device;
+	struct _device	*pc_device;		/* CPU device handle */
 	void		*pc_netisr;		/* netisr SWI cookie */
 	int		pc_unused1;		/* unused field */
 	int		pc_domain;		/* Memory domain. */

sys/sys/systm.h

@@ -626,9 +626,8 @@ void counted_warning(unsigned *counter, const char *msg);
 /*
  * APIs to manage deprecation and obsolescence.
  */
-struct device;
 void _gone_in(int major, const char *msg);
-void _gone_in_dev(struct device *dev, int major, const char *msg);
+void _gone_in_dev(device_t dev, int major, const char *msg);
 #ifdef NO_OBSOLETE_CODE
 #define __gone_ok(m, msg)					 \
 	_Static_assert(m < P_OSREL_MAJOR(__FreeBSD_version)),	 \
@@ -641,5 +640,4 @@ void _gone_in_dev(struct device *dev, int major, const char *msg);
 #endif /* _KERNEL */
 
 __NULLABILITY_PRAGMA_POP
-
 #endif /* !_SYS_SYSTM_H_ */

sys/sys/types.h

@@ -272,7 +272,7 @@ typedef __rman_res_t    rman_res_t;
 
 #ifdef _KERNEL
 typedef	int		boolean_t;
-typedef	struct device	*device_t;
+typedef	struct _device	*device_t;
 typedef	__intfptr_t	intfptr_t;
 
 /*