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rman_release_resource.9freebsd

BSD mandoc

NAME

rman rman_activate_resource rman_await_resource rman_deactivate_resource rman_fini rman_init rman_manage_region rman_release_resource rman_reserve_resource rman_reserve_resource_bound rman_make_alignment_flags rman_get_start rman_get_end rman_get_device rman_get_size rman_get_flags rman_set_virtual rman_get_virtual rman_set_bustag rman_get_bustag rman_set_bushandle rman_get_bushandle rman_set_rid rman_get_rid - resource management functions

SYNOPSIS

In sys/rman.h Ft int Fn rman_activate_resource struct resource *r Ft int Fn rman_await_resource struct resource *r int pri2 int timo Ft int Fn rman_deactivate_resource struct resource *r Ft int Fn rman_fini struct rman *rm Ft int Fn rman_init struct rman *rm Ft int Fn rman_manage_region struct rman *rm u_long start u_long end Ft int Fn rman_release_resource struct resource *r Ft struct resource * Fo rman_reserve_resource Fa struct rman *rm u_long start u_long end u_long count Fa u_int flags struct device *dev Fc Ft struct resource * Fo rman_reserve_resource_bound Fa struct rman *rm u_long start u_long end u_long count Fa u_long bound u_int flags struct device *dev Fc Ft uint32_t Fn rman_make_alignment_flags uint32_t size Ft u_long Fn rman_get_start struct resource *r Ft u_long Fn rman_get_end struct resource *r Ft struct device * Fn rman_get_device struct resource *r Ft u_long Fn rman_get_size struct resource *r Ft u_int Fn rman_get_flags struct resource *r Ft void Fn rman_set_virtual struct resource *r void *v Ft void * Fn rman_get_virtual struct resource *r Ft void Fn rman_set_bustag struct resource *r bus_space_tag_t t Ft bus_space_tag_t Fn rman_get_bustag struct resource *r Ft void Fn rman_set_bushandle struct resource *r bus_space_handle_t h Ft bus_space_handle_t Fn rman_get_bushandle struct resource *r Ft void Fn rman_set_rid struct resource *r int rid Ft int Fn rman_get_rid struct resource *r

DESCRIPTION

The set of functions provides a flexible resource management abstraction. It is used extensively by the bus management code. It implements the abstractions of region and resource. A region descriptor is used to manage a region; this could be memory or some other form of bus space.

Each region has a set of bounds. Within these bounds, allocated segments may reside. Each segment, termed a resource, has several properties which are represented by a 16-bit flag register, as follows.

 #define RF_ALLOCATED    0x0001 /* resource has been reserved */
 #define RF_ACTIVE       0x0002 /* resource allocation has been activated */
 #define RF_SHAREABLE    0x0004 /* resource permits contemporaneous sharing */
 #define RF_TIMESHARE    0x0008 /* resource permits time-division sharing */
 #define RF_WANTED       0x0010 /* somebody is waiting for this resource */
 #define RF_FIRSTSHARE   0x0020 /* first in sharing list */
 #define RF_PREFETCHABLE 0x0040 /* resource is prefetchable */
 

The remainder of the flag bits are used to represent the desired alignment of the resource within the region.

The Fn rman_init function initializes the region descriptor, pointed to by the Fa rm argument, for use with the resource management functions. It is required that the fields rm_type and rm_descr of Vt struct rman be set before calling Fn rman_init . The field rm_type shall be set to RMAN_ARRAY The field rm_descr shall be set to a string that describes the resource to be managed. It also initializes any mutexes associated with the structure. If Fn rman_init fails to initalize the mutex, it will return Er ENOMEM ; otherwise it will return 0 and Fa rm will be initalized.

The Fn rman_fini function frees any structures associated with the structure pointed to by the Fa rm argument. If any of the resources within the managed region have the RF_ALLOCATED flag set, it will return Er EBUSY ; otherwise, any mutexes associated with the structure will be released and destroyed, and the function will return 0.

The Fn rman_manage_region function establishes the concept of a region which is under control. The Fa rman argument points to the region descriptor. The Fa start and Fa end arguments specify the bounds of the region. If successful, Fn rman_manage_region will return 0. If the region overlaps with an existing region, it will return Er EBUSY . Er ENOMEM will be return when Fn rman_manage_region failed to allocate memory for the region.

The Fn rman_reserve_resource_bound function is where the bulk of the logic is located. It attempts to reserve a contiguous range in the specified region Fa rm for the use of the device Fa dev . The caller can specify the Fa start and Fa end of an acceptable range, as well as alignment, and the code will attempt to find a free segment which fits. The Fa start argument is the lowest acceptable starting value of the resource. The Fa end argument is the highest acceptable ending value of the resource. Therefore, Fa start No + Fa count No - 1 must be ≤ Fa end for any allocation to happen. The default behavior is to allocate an exclusive segment, unless the RF_SHAREABLE or RF_TIMESHARE flags are set, in which case a shared segment will be allocated. If this shared segment already exists, the caller has its device added to the list of consumers.

The Fn rman_reserve_resource function is used to reserve resources within a previously established region. It is a simplified interface to Fn rman_reserve_resource_bound which passes 0 for the Fa flags argument.

The Fn rman_make_alignment_flags function returns the flag mask corresponding to the desired alignment Fa size . This should be used when calling Fn rman_reserve_resource_bound .

The Fn rman_release_resource function releases the reserved resource Fa r . It may attempt to merge adjacent free resources.

The Fn rman_activate_resource function marks a resource as active, by setting the RF_ACTIVE flag. If this is a time shared resource, and the caller has not yet acquired the resource, the function returns Er EBUSY .

The Fn rman_deactivate_resource function marks a resource Fa r as inactive, by clearing the RF_ACTIVE flag. If other consumers are waiting for this range, it will wakeup their threads.

The Fn rman_await_resource function performs an asynchronous wait for a resource Fa r to become inactive, that is, for the RF_ACTIVE flag to be cleared. It is used to enable cooperative sharing of a resource which can only be safely used by one thread at a time. The arguments Fa pri and Fa timo are passed to the Fn rman_await_resource function.

The Fn rman_get_start , Fn rman_get_end , Fn rman_get_size , and Fn rman_get_flags functions return the bounds, size and flags of the previously reserved resource Fa r .

The Fn rman_set_bustag function associates a Vt bus_space_tag_t Fa t with the resource Fa r . The Fn rman_get_bustag function is used to retrieve this tag once set.

The Fn rman_set_bushandle function associates a Vt bus_space_handle_t Fa h with the resource Fa r . The Fn rman_get_bushandle function is used to retrieve this handle once set.

The Fn rman_set_virtual function is used to associate a kernel virtual address with a resource Fa r . The Fn rman_get_virtual function can be used to retrieve the KVA once set.

The Fn rman_set_rid function associates a resource identifier with a resource Fa r . The Fn rman_get_rid function retrieves this RID.

The Fn rman_get_device function returns a pointer to the device which reserved the resource Fa r .

SEE ALSO

bus_activate_resource9, bus_alloc_resource9, bus_release_resource9, bus_set_resource9, mutex(9)

AUTHORS

This manual page was written by An Bruce M Simpson Aq bms@spc.org .