4 * Copyright (C) 2002-2005 - Tom Zanussi <zanussi@us.ibm.com>, IBM Corp
5 * Copyright (C) 1999-2005 - Karim Yaghmour <karim@opersys.com>
6 * Copyright (C) 2008-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 * Re-using content from kernel/relay.c.
10 * This file is released under the GPL v2.
13 #include <linux/module.h>
16 #include "../../wrapper/ringbuffer/backend.h"
17 #include "../../wrapper/ringbuffer/frontend.h"
18 #include "../../wrapper/ringbuffer/vfs.h"
21 * fault() vm_op implementation for ring buffer file mapping.
23 static int lib_ring_buffer_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
25 struct lib_ring_buffer
*buf
= vma
->vm_private_data
;
26 struct channel
*chan
= buf
->backend
.chan
;
27 const struct lib_ring_buffer_config
*config
= chan
->backend
.config
;
28 pgoff_t pgoff
= vmf
->pgoff
;
31 unsigned long offset
, sb_bindex
;
34 * Verify that faults are only done on the range of pages owned by the
37 offset
= pgoff
<< PAGE_SHIFT
;
38 sb_bindex
= subbuffer_id_get_index(config
, buf
->backend
.buf_rsb
.id
);
39 if (!(offset
>= buf
->backend
.array
[sb_bindex
]->mmap_offset
40 && offset
< buf
->backend
.array
[sb_bindex
]->mmap_offset
+
41 buf
->backend
.chan
->backend
.subbuf_size
))
42 return VM_FAULT_SIGBUS
;
44 * ring_buffer_read_get_page() gets the page in the current reader's
47 page
= lib_ring_buffer_read_get_page(&buf
->backend
, offset
, &virt
);
49 return VM_FAULT_SIGBUS
;
57 * vm_ops for ring buffer file mappings.
59 static const struct vm_operations_struct lib_ring_buffer_mmap_ops
= {
60 .fault
= lib_ring_buffer_fault
,
64 * lib_ring_buffer_mmap_buf: - mmap channel buffer to process address space
65 * @buf: ring buffer to map
66 * @vma: vm_area_struct describing memory to be mapped
68 * Returns 0 if ok, negative on error
70 * Caller should already have grabbed mmap_sem.
72 static int lib_ring_buffer_mmap_buf(struct lib_ring_buffer
*buf
,
73 struct vm_area_struct
*vma
)
75 unsigned long length
= vma
->vm_end
- vma
->vm_start
;
76 struct channel
*chan
= buf
->backend
.chan
;
77 const struct lib_ring_buffer_config
*config
= chan
->backend
.config
;
78 unsigned long mmap_buf_len
;
80 if (config
->output
!= RING_BUFFER_MMAP
)
83 mmap_buf_len
= chan
->backend
.buf_size
;
84 if (chan
->backend
.extra_reader_sb
)
85 mmap_buf_len
+= chan
->backend
.subbuf_size
;
87 if (length
!= mmap_buf_len
)
90 vma
->vm_ops
= &lib_ring_buffer_mmap_ops
;
91 vma
->vm_flags
|= VM_DONTEXPAND
;
92 vma
->vm_private_data
= buf
;
98 * lib_ring_buffer_mmap - mmap file op
100 * @vma: the vma describing what to map
102 * Calls upon lib_ring_buffer_mmap_buf() to map the file into user space.
104 int lib_ring_buffer_mmap(struct file
*filp
, struct vm_area_struct
*vma
)
106 struct lib_ring_buffer
*buf
= filp
->private_data
;
107 return lib_ring_buffer_mmap_buf(buf
, vma
);
109 EXPORT_SYMBOL_GPL(lib_ring_buffer_mmap
);