Shared Memory

Shared Memory. More...

Data Structures
struct	shmem_object_t
	Represents a shared memory object. More...

Functions
static void	shmem_object_free (shmem_object_t *shmem)
static shmem_object_t *	shmem_object_new (void)
static void	shmem_vmm_callback (void *private)
static void *	shmem_object_allocate_pages (shmem_object_t *shmem, uint64_t pageAmount, space_t *space, void *address, pml_flags_t flags)
static uint64_t	shmem_open (file_t *file)
static void	shmem_close (file_t *file)
static void *	shmem_mmap (file_t *file, void *address, uint64_t length, uint64_t *offset, pml_flags_t flags)
static uint64_t	shmem_init (void)
static void	shmem_deinit (void)

Variables
static dentry_t *	shmemDir = NULL
static dentry_t *	newFile = NULL
static file_ops_t	fileOps

Detailed Description

Shared Memory.

Shared memory is exposed in the /dev/shmem directory. Shared memory allows multiple processes to share a section of memory for inter-process communication (IPC).

Creating Shared Memory

Shared memory objects are created using the /dev/shmem/new file. Opening this file using open() will create a new anonymous shared memory object and return a file descriptor to it.

Using Shared Memory

Shared memory objects can be mapped to the current process's address space using the mmap() system call. The first call to mmap() will decide the size of the shared memory object. Subsequent calls to mmap() will map the existing shared memory object.

Function Documentation

shmem_close()

static void shmem_close ( file_t *  file )

static

Definition at line 157 of file shmem.c.

References DEREF, file, NULL, and dentry_t::private.

shmem_deinit()

static void shmem_deinit ( void  )

static

Definition at line 249 of file shmem.c.

References DEREF, newFile, NULL, and shmemDir.

Referenced by _module_procedure().

shmem_init()

static uint64_t shmem_init ( void  )

static

Definition at line 229 of file shmem.c.

References DEREF, ERR, fileOps, LOG_ERR, newFile, NULL, shmemDir, sysfs_dir_new(), and sysfs_file_new().

Referenced by _module_procedure().

shmem_mmap()

static void * shmem_mmap ( file_t *  file, void *  address, uint64_t  length, uint64_t *  offset, pml_flags_t  flags  )

static

Definition at line 168 of file shmem.c.

References address, assert, BYTES_TO_PAGES, EINVAL, errno, file, shmem_object_t::lock, LOCK_SCOPE, MIN, NULL, PAGE_SIZE, pageAmount, shmem_object_t::pageAmount, shmem_object_t::pages, dentry_t::private, REF, sched_process_unsafe(), shmem_object_allocate_pages(), shmem_vmm_callback(), process_t::space, and vmm_map_pages().

shmem_object_allocate_pages()

static void * shmem_object_allocate_pages ( shmem_object_t *  shmem, uint64_t  pageAmount, space_t *  space, void *  address, pml_flags_t  flags  )

static

Definition at line 100 of file shmem.c.

References address, free(), malloc(), NULL, pageAmount, shmem_object_t::pageAmount, shmem_object_t::pages, pmm_alloc(), pmm_free(), REF, shmem_vmm_callback(), and vmm_map_pages().

Referenced by shmem_mmap().

shmem_object_free()

static void shmem_object_free ( shmem_object_t *  shmem )

static

Definition at line 54 of file shmem.c.

References assert, free(), NULL, shmem_object_t::pageAmount, shmem_object_t::pages, and pmm_free().

Referenced by shmem_object_new().

shmem_object_new()

static shmem_object_t * shmem_object_new ( void  )

static

Definition at line 74 of file shmem.c.

References shmem_object_t::lock, lock_init(), malloc(), NULL, shmem_object_t::pageAmount, shmem_object_t::pages, shmem_object_t::ref, ref_init(), and shmem_object_free().

Referenced by shmem_open().

shmem_open()

static uint64_t shmem_open ( file_t *  file )

static

Definition at line 145 of file shmem.c.

References ERR, file, NULL, dentry_t::private, and shmem_object_new().

shmem_vmm_callback()

static void shmem_vmm_callback ( void *  private )

static

Definition at line 89 of file shmem.c.

References DEREF, and NULL.

Referenced by shmem_mmap(), and shmem_object_allocate_pages().

Variable Documentation

fileOps

file_ops_t fileOps

static

Initial value:

= {
    .open = shmem_open,
    .close = shmem_close,
    .mmap = shmem_mmap,
}

Definition at line 223 of file shmem.c.

Referenced by shmem_init().

newFile

dentry_t* newFile = NULL

static

Definition at line 52 of file shmem.c.

Referenced by shmem_deinit(), and shmem_init().

shmemDir

dentry_t* shmemDir = NULL

static

Definition at line 51 of file shmem.c.

Referenced by shmem_deinit(), and shmem_init().