source: trunk/kernel/kern/process.h @ 619

Last change on this file since 619 was 618, checked in by alain, 5 years ago

fix a bug in process_destroy() : the vmm_destroy() must be called before
the PID release.
File size: 37.1 KB
Line 
1/*
2 * process.h - process related functions definition.
3 *
4 * Authors  Ghassan Almaless (2008,2009,2010,2011,2012)
5 *          Mohamed Lamine Karaoui (2015)
6 *          Alain Greiner (2016,2017,2018)
7 *
8 * Copyright (c) UPMC Sorbonne Universites
9 *
10 * This file is part of ALMOS-MKH.
11 *
12 * ALMOS-MKH is free software; you can redistribute it and/or modify it
13 * under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; version 2.0 of the License.
15 *
16 * ALMOS-MKH is distributed in the hope that it will be useful, but
17 * WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
19 * General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
23 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
24 */
25
26#ifndef _PROCESS_H_
27#define _PROCESS_H_
28
29#include <kernel_config.h>
30#include <errno.h>
31#include <hal_kernel_types.h>
32#include <list.h>
33#include <xlist.h>
34#include <bits.h>
35#include <busylock.h>
36#include <rwlock.h>
37#include <queuelock.h>
38#include <remote_queuelock.h>
39#include <remote_rwlock.h>
40#include <hal_atomic.h>
41#include <vmm.h>
42#include <cluster.h>
43#include <vfs.h>
44
45/****  Forward declarations  ****/
46
47struct thread_s;
48
49/*********************************************************************************************
50 * These macros are used to compose or decompose global process identifier (PID)
51 * to or from cluster identifier / local process index (CXY , LPID)
52 ********************************************************************************************/
53
54#define LPID_FROM_PID( pid )       (lpid_t)(pid & 0x0000FFFF)
55#define CXY_FROM_PID( pid )        (cxy_t)(pid >> 16)
56#define PID( cxy , lpid )          (pid_t)((cxy << 16) | lpid )
57
58/*********************************************************************************************
59 * This enum defines the actions that can be executed by the process_sigaction() function.
60 ********************************************************************************************/
61
62typedef enum 
63{
64    BLOCK_ALL_THREADS    = 0x11,
65    UNBLOCK_ALL_THREADS  = 0x22,
66    DELETE_ALL_THREADS   = 0x33, 
67} 
68process_sigactions_t;
69
70/*********************************************************************************************
71 * This structure defines an array of extended pointers on the open file descriptors
72 * for a given process. We use an extended pointer because the open file descriptor
73 * is always stored in the same cluster as the inode associated to the file.
74 * A free entry in this array contains the XPTR_NULL value.
75 * The array size is defined by a the CONFIG_PROCESS_FILE_MAX_NR parameter.
76 *
77 * NOTE: - Only the fd_array[] in the reference process contains a complete list of open
78 *         files, and is protected by the lock against concurrent access.
79 *       - the fd_array[] in a process copy is simply a cache containing a subset of the
80 *         open files to speed the fdid to xptr translation, but the "lock" and "current
81 *         fields should not be used.
82 *       - all modifications made by the process_fd_remove() are done in reference cluster
83 *         and reported in all process_copies.
84 ********************************************************************************************/
85
86typedef struct fd_array_s
87{
88        remote_queuelock_t lock;                              /*! lock protecting fd_array      */
89    uint32_t           current;                           /*! current number of open files  */
90        xptr_t             array[CONFIG_PROCESS_FILE_MAX_NR]; /*! open file descriptors         */
91}
92fd_array_t;
93
94/*********************************************************************************************
95 * This structure defines a process descriptor.
96 * A process is identified by a unique PID (process identifier):
97 * - The PID 16 LSB bits contain the LPID (Local Process Index)
98 * - The PID 16 MSB bits contain the owner cluster CXY.
99 * In each cluster, the process manager allocates  the LPID values for the process that
100 * are owned by this cluster.
101 * The process descriptor is replicated in all clusters containing at least one thread
102 * of the PID process, with the following rules :
103 * 1) The <pid>, <ppid>, <ref_xp>, <owner_xp>, <vfs_root_xp>, <vfs_bin_xp>  fields are
104 *    defined in all process descriptor copies.
105 * 2) The <vfs_cwd_xp> and associated <cwd_lock>, that can be dynamically modified,
106 *    are only defined in the reference process descriptor.
107 * 2) The <vmm>, containing the VSL (list of registered vsegs), and the GPT (generic
108 *    page table), are only complete in the reference process cluster, other copies
109 *    are actually use as read-only caches.
110 * 3) the <fd_array>, containing extended pointers on the open file descriptors, is only
111 *    complete in the reference process cluster, other copies are read-only caches.
112 * 4) The <sem_root>, <mutex_root>, <barrier_root>, <condvar_root>, and the associated
113 *    <sync_lock>, dynamically allocated, are only defined in the reference cluster.
114 * 5) The <children_root>, <children_nr>, <children_list>, and <txt_list> fields are only
115 *    defined in the reference cluster, and are undefined in other clusters.
116 * 6) The <local_list>, <copies_list>, <th_tbl>, <th_nr>, <u_th_lock> or <k_th_lock> fields
117 *    are specific in each cluster, and are defined in all process descriptors copies.
118 * 7) The termination <flags> and <exit_status> are only defined in the reference cluster.
119 *    (The term_state format is defined in the shared_syscalls.h file ).
120 ********************************************************************************************/
121
122typedef struct process_s
123{
124        vmm_t              vmm;              /*! embedded virtual memory manager                 */
125
126        fd_array_t         fd_array;         /*! embedded open file descriptors array            */
127
128        xptr_t             vfs_root_xp;      /*! extended pointer on VFS root inode              */
129        xptr_t             vfs_bin_xp;       /*! extended pointer on .elf file descriptor        */
130        pid_t              pid;              /*! process identifier                              */
131    xptr_t             ref_xp;           /*! extended pointer on reference process           */
132    xptr_t             owner_xp;         /*! extended pointer on owner process               */
133    xptr_t             parent_xp;        /*! extended pointer on parent process              */
134
135        xptr_t             cwd_xp;           /*! extended pointer on current working dir inode   */
136        remote_busylock_t  cwd_lock;         /*! lock protecting working directory changes       */
137
138        xlist_entry_t      children_root;    /*! root of the children process xlist              */
139    remote_queuelock_t children_lock;    /*! lock protecting children process xlist          */
140    uint32_t           children_nr;      /*! number of children processes                    */
141
142        xlist_entry_t      children_list;    /*! member of list of children of same parent       */
143    xlist_entry_t      local_list;       /*! member of list of process in same cluster       */
144    xlist_entry_t      copies_list;      /*! member of list of copies of same process        */
145    xlist_entry_t      txt_list;         /*! member of list of processes sharing same TXT    */
146
147        struct thread_s  * th_tbl[CONFIG_THREADS_MAX_PER_CLUSTER];       /*! local threads       */
148
149        uint32_t           th_nr;            /*! number of threads in this cluster               */
150    rwlock_t           th_lock;          /*! lock protecting th_tbl[]  i                     */ 
151
152    xlist_entry_t      sem_root;         /*! root of the user defined semaphore list         */
153    xlist_entry_t      mutex_root;       /*! root of the user defined mutex list             */
154    xlist_entry_t      barrier_root;     /*! root of the user defined barrier list           */
155    xlist_entry_t      condvar_root;     /*! root of the user defined condvar list           */
156    remote_queuelock_t sync_lock;        /*! lock protecting user defined synchro lists      */
157
158    xlist_entry_t      dir_root;         /*! root of the user defined DIR list               */
159    remote_queuelock_t dir_lock;         /*! lock protexting user defined DIR list           */
160
161    uint32_t           term_state;       /*! termination status (flags & exit status)        */
162}
163process_t;
164
165/*********************************************************************************************
166 * This structure defines the information required by the process_make_exec() function
167 * to create a new reference process descriptor, and the associated main thread.
168 ********************************************************************************************/
169
170typedef struct exec_info_s
171{
172    char               path[CONFIG_VFS_MAX_PATH_LENGTH];   /*!  .elf file path              */
173
174    char            ** args_pointers;  /*! physical base address of array of pointers       */
175    char             * args_buf_base;  /*! physical base address of kernel args buffer      */
176    uint32_t           args_nr;        /*! actual number of arguments                       */
177
178    char            ** envs_pointers;  /*! physical base address of array of pointers       */
179    char             * envs_buf_base;  /*! physical base address of kernel args buffer      */
180    char             * envs_buf_free;  /*! physical address of first free slot in envs_buf  */
181    uint32_t           envs_nr;        /*! actual number of environment variables           */
182}
183exec_info_t;
184
185/***************   Process Descriptor Operations    *****************************************/
186
187/*********************************************************************************************
188 * This function allocates memory in local cluster for a process descriptor.
189 *********************************************************************************************
190 * @ returns pointer on process descriptor if success / return NULL if failure
191 ********************************************************************************************/
192process_t * process_alloc( void );
193
194/*********************************************************************************************
195 * This function releases memory in local cluster for a process descriptor.
196 *********************************************************************************************
197 * @ process      : pointer on process descriptor to release.
198 ********************************************************************************************/
199void process_free( process_t * process );
200
201/*********************************************************************************************
202 * This function initialize, in each cluster, the kernel "process_zero", that is the owner
203 * of all kernel threads in a given cluster. It is called by the kernel_init() function.
204 * The process_zero descriptor is allocated as a global variable in file kernel_init.c
205 * Both the PID and PPID fields are set to zero, the ref_xp is the local process_zero,
206 * and the parent process is set to XPTR_NULL. The th_tbl[] is initialized as empty.
207 *********************************************************************************************
208 * @ process      : [in] pointer on local process descriptor to initialize.
209 ********************************************************************************************/
210void process_zero_create( process_t * process );
211
212/*********************************************************************************************
213 * This function allocates memory and initializes the "process_init" descriptor and the
214 * associated "thread_init" descriptor. It is called once at the end of the kernel
215 * initialisation procedure. Its local process identifier is 1, and parent process
216 * is the kernel process in cluster 0.
217 * The "process_init" is the first user process, and all other user processes will be forked
218 * from this process. The code executed by "process_init" is stored in a .elf file, whose
219 * pathname is defined by the CONFIG_PROCESS_INIT_PATH configuration variable.
220 * The process_init does not use the [STDIN/STDOUT/STDERR] streams, but it is linked
221 * to kernel TXT0, because these streams must be defined for all user processes.
222 ********************************************************************************************/
223void process_init_create( void );
224
225/*********************************************************************************************
226 * This function initializes a reference, user process descriptor from another process
227 * descriptor, defined by the <parent_xp> argument. The <process> and <pid> arguments
228 * are previously allocated by the caller. This function can be called by two functions:
229 * 1) process_init_create() : process is the INIT process; parent is process-zero.
230 * 2) process_make_fork() : the parent process descriptor is generally remote.
231 * The following fields are initialised :
232 * - It set the pid / ppid / ref_xp / parent_xp / state fields.
233 * - It initializes the VMM (register the kentry, args, envs vsegs in VSL)
234 * - It initializes the FDT, defining the three pseudo files STDIN / STDOUT / STDERR.
235 *   . if INIT process     => link to kernel TXT[0].
236 *   . if KSH[i] process   => allocate a free TXT[i] and give TXT ownership.
237 *   . if USER process     => same TXT[i] as parent process and give TXT ownership.
238 * - It set the root_xp, bin_xp, cwd_xp fields.
239 * - It reset the children list as empty, but does NOT register it in parent children list.
240 * - It reset the TH_TBL list of threads as empty.
241 * - It reset the semaphore / mutex / barrier / condvar lists as empty.
242 * - It registers the process in the local_list, rooted in the local cluster manager.
243 * - It registers the process in the copies_list, rooted in the owner cluster manager.
244 * - It registers the process extended pointer in the local pref_tbl[] array.
245 *********************************************************************************************
246 * @ process      : [in] pointer on local process descriptor to initialize.
247 * @ pid          : [in] process identifier.
248 * @ parent_xp    : [in] extended pointer on parent process descriptor.
249 ********************************************************************************************/
250void process_reference_init( process_t * process,
251                             pid_t       pid,
252                             xptr_t      parent_xp );
253
254/*********************************************************************************************
255 * This function initializes a copy process descriptor, in the local cluster,
256 * from information defined in the reference remote process descriptor.
257 *********************************************************************************************
258 * @ process              : [in] local pointer on process descriptor to initialize.
259 * @ reference_process_xp : [in] extended pointer on reference process descriptor.
260 * @ return 0 if success / return ENOMEM if failure
261 ********************************************************************************************/
262error_t process_copy_init( process_t * local_process,
263                           xptr_t      reference_process_xp );
264
265/*********************************************************************************************
266 * This function releases all memory allocated for a process descriptor in the local cluster,
267 * including memory allocated for embedded substructures (fd_array, vmm, etc).
268 * The local th_tbl[] array must be empty.
269 *********************************************************************************************
270 * @ process     : pointer on the process descriptor.
271 ********************************************************************************************/
272void process_destroy( process_t * process );
273
274/*********************************************************************************************
275 * This debug function diplays on the kernel terminal TXT0 detailed informations on a
276 * process descriptor identified by the <process_xp> argument.
277 * It can be called by a thread running in any cluster.
278 * WARNING: this function uses the nolock_printk() function, and the  TXT0 lock MUST be
279 * taken by the caller function.
280 *********************************************************************************************
281 * @ process_xp : extended pointer on process descriptor.
282 ********************************************************************************************/
283void process_display( xptr_t process_xp );
284
285/*********************************************************************************************
286 * This function returns a printable string defining the sigaction type.
287 *********************************************************************************************
288 * @ sigaction_type   : BLOCK_ALL_THREADS / UNBLOCK_ALL_THREADS / DELETE_ALL_THREADS
289 * @ return a string pointer.
290 ********************************************************************************************/
291const char * process_action_str( process_sigactions_t sigaction_type );
292
293/*********************************************************************************************
294 * This function allows a client thread running in any cluster to block, unblock or delete
295 * all threads of a process identified by the <pid> argument, depending on the
296 * <action_type> argument.
297 *
298 * It uses the multicast, non blocking rpc_process_sigaction_client() function to send
299 * parallel requests to all remote clusters containing process copies.
300 * Then it blocks and deschedule to wait completion of these parallel requests.
301 *
302 * It is used by the sys_kill() & sys_exit() functions to handle the "kill" & "exit" syscalls.
303 * It is also used by the process_make_exec() function to handle the "exec" syscall.
304 * It is also called by the TXT device ISR to execute the ctrl C & ctrl Z commands.
305 *
306 * WARNING (1) the DELETE action is NOT executed on the target process main thread
307 * (thread 0 in process owner cluster), and not executed on the client thread itself.
308 *
309 * WARNING (2) the BLOCK action is executed on all target process threads, and this function
310 * returns only when all threads BUT the client thread are actually blocked and not running.
311 * When the client thread is also a target thread, it is blocked but not descheduled.
312 *
313 * WARNING (3) the UNBLOCK action is executed on all target process threads, as the
314 * client thread cannot be a target thread.
315 *
316 * Implementation note:
317 * This function allocates a - shared - RPC descriptor in client thread stack,
318 * and initializes it. This RPC descriptor can be shared because all parallel,
319 * non-blocking, RPC server threads use the same input arguments, including the
320 * RPC responses counter field.
321 *********************************************************************************************
322 * @ pid         : target process identifier.
323 * @ action_type : BLOCK_ALL_THREADS / UNBLOCK_ALL_THREADS / DELETE_ALL_THREADS
324 ********************************************************************************************/
325void process_sigaction( pid_t       pid,
326                        uint32_t    action_type );
327
328/*********************************************************************************************
329 * This function marks for delete all threads for a given <process> in the local cluster.
330 * It scan the list of local thread, and sets the THREAD_FLAG_REQ_DELETE bit for all
331 * threads, BUT the main thread (thread 0 in owner cluster), and the client thread
332 * identified by the <client_xp> argument.
333 * The actual delete will be done by the scheduler at the next scheduling point.
334 *********************************************************************************************
335 * @ process     : pointer on the process descriptor.
336 * @ client_xp   : extended pointer on the client thread that should not be marked.
337 ********************************************************************************************/
338void process_delete_threads( process_t * process,
339                             xptr_t      client_xp );
340
341/*********************************************************************************************
342 * This function blocks all threads for a given <process> in the local cluster.
343 * It scan the list of local thread, and sets the THREAD_BLOCKED_GLOBAL bit for all threads.
344 * It request the relevant schedulers to acknowledge the blocking, using IPI if required,
345 * when the target thread is running on another core than the calling thread.
346 * It returns only when all threads in cluster, including the caller are actually blocked.
347 * The threads are not detached from the scheduler, and not detached from the local process.
348 *********************************************************************************************
349 * @ process     : pointer on the target process descriptor.
350 ********************************************************************************************/
351void process_block_threads( process_t * process );
352
353/*********************************************************************************************
354 * This function unblocks all threads of a given user process in a given cluster.
355 *********************************************************************************************
356 * @ process     : pointer on the process descriptor.
357 ********************************************************************************************/
358void process_unblock_threads( process_t * process );
359
360/*********************************************************************************************
361 * This function returns a pointer on the local copy of a process identified by its PID.
362 * If this local copy does not exist yet, it is dynamically created, from the reference
363 * process descriptor, registered in the global copies_list, and registered in the local_list.
364 * This function is used by the thread_user_create() function.
365 *********************************************************************************************
366 * @ pid     : searched process identifier.
367 * @ returns pointer on the local process descriptor if success / returns NULL if failure.
368 ********************************************************************************************/
369process_t * process_get_local_copy( pid_t pid );
370
371/*********************************************************************************************
372 * This function returns the parent process identifier for a remote process descriptor
373 * identified by an extended pointer.
374 *********************************************************************************************
375 * @ process_xp   : extended pointer on remote process descriptor.
376 * @ returns parent process dentifier.
377 ********************************************************************************************/
378pid_t process_get_ppid( xptr_t process_xp );
379
380/*********************************************************************************************
381 * This function implements the "exec" system call, and is called by the sys_exec() function.
382 * The "new" process keep the "old" process PID and PPID, all open files, and env variables,
383 * the vfs_root and vfs_cwd, but build a brand new memory image (new VMM from the new .elf).
384 * It is executed in the local cluster, that becomes both the "owner" and the "reference"
385 * cluster for the "new" process.
386 *********************************************************************************************
387 * @ exec_info   : [in]  pointer on the exec_info structure.
388 * @ return 0 if success / return non-zero if error.
389 ********************************************************************************************/
390error_t process_make_exec( exec_info_t * exec_info );
391
392/*********************************************************************************************
393 * This function implements the "fork" system call, and is called by the sys_fork() function,
394 * likely throuch the RPC_PROCESS_MAKE_FORK.
395 * It allocates memory and initializes a new "child" process descriptor, and the associated
396 * "child" thread descriptor in local cluster. It involves up to three different clusters :
397 * - the child (local) cluster can be any cluster selected by the sys_fork function.
398 * - the parent cluster must be the reference cluster for the parent process.
399 * - the client cluster containing the thread requesting the fork can be any cluster.
400 * The new "child" process descriptor is initialised from informations found in the "parent"
401 * reference process descriptor, containing the complete process description.
402 * The new "child" thread descriptor is initialised from informations found in the "parent"
403 * thread descriptor.
404 *********************************************************************************************
405 * @ parent_process_xp  : extended pointer on the reference parent process.
406 * @ parent_thread_xp   : extended pointer on the parent thread requesting the fork.
407 * @ child_pid          : [out] child process identifier.
408 * @ child_thread_ptr   : [out] local pointer on child thread in target cluster.
409 * @ return 0 if success / return non-zero if error.
410 ********************************************************************************************/
411error_t process_make_fork(  xptr_t             parent_process_xp,
412                            xptr_t             parent_thread_xp,
413                            pid_t            * child_pid, 
414                            struct thread_s ** child_thread_ptr );
415
416
417/********************   File Management Operations   ****************************************/
418
419/*********************************************************************************************
420 * This function initializes all entries of the local fd_array as empty.
421 *********************************************************************************************
422 * @ process  : pointer on the local process descriptor.
423 ********************************************************************************************/
424void process_fd_init( process_t * process );
425
426/*********************************************************************************************
427 * This function allocates a free slot in the fd_array of the reference process
428 * identified by the <process_xp> argument, register the <file_xp> argument in the
429 * allocated slot, and return the slot index in the <fdid> buffer.
430 * It can be called by any thread in any cluster, because it uses portable remote access
431 * primitives to access the reference process descriptor.
432 * It takes the lock protecting the reference fd_array against concurrent accesses.
433 *********************************************************************************************
434 * @ process_xp : [in]  extended pointer on client reference process.
435 * @ file_xp    : [in]  extended pointer on the file descriptor to be registered.
436 * @ fdid       : [out] buffer for fd_array slot index.
437 * @ return 0 if success / return EMFILE if array full.
438 ********************************************************************************************/
439error_t process_fd_register( xptr_t      process_xp,
440                             xptr_t      file_xp,
441                             uint32_t  * fdid );
442
443/*********************************************************************************************
444 * This function uses as many remote accesses as required, to reset an entry in fd_array[],
445 * in all clusters containing a copy. The entry is identified by the <fdid> argument.
446 * This function must be executed by a thread running in reference cluster, that contains
447 * the complete list of process descriptors copies.
448 * It takes the lock protecting the reference fd_array against concurrent accesses.
449 * TODO this function is not implemented yet.
450 *********************************************************************************************
451 * @ process  : [in] pointer on the local process descriptor.
452 * @ fdid     : [in] file descriptor index in the fd_array.
453 ********************************************************************************************/
454void process_fd_remove( process_t * process,
455                        uint32_t    fdid );
456
457/*********************************************************************************************
458 * This function returns an extended pointer on a file descriptor identified by its index
459 * in fd_array. It can be called by any thread running in any cluster.
460 * It accesses first the local process descriptor. In case of local miss, it takes
461 * the lock protecting the reference fd_array, and access the reference process descriptor.
462 * It updates the local fd_array when the file descriptor exists in reference cluster.
463 * It takes the lock protecting the reference fd_array against concurrent accesses.
464 * The file descriptor refcount is not incremented.
465 *********************************************************************************************
466 * @ process  : pointer on the local process descriptor.
467 * @ fdid     : file descriptor index in the fd_array.
468 * @ return extended pointer on file descriptor if success / return XPTR_NULL if not found.
469 ********************************************************************************************/
470xptr_t process_fd_get_xptr( process_t * process,
471                            uint32_t    fdid );
472
473/*********************************************************************************************
474 * This function copies all non-zero entries (other than the three first stdin/stdout/stderr)
475 * from a remote <src_xp> fd_array, embedded in a process descriptor, to another remote
476 * <dst_xp> fd_array, embedded in another process descriptor.
477 * The calling thread can be running in any cluster.
478 * It takes the lock protecting the reference fd_array against concurrent accesses.
479 * For each involved file descriptor, the refcount is incremented.
480 *********************************************************************************************
481 * @ dst_xp   : extended pointer on the destination fd_array_t.
482 * @ src_xp   : extended pointer on the source fd_array_t.
483 ********************************************************************************************/
484void process_fd_remote_copy( xptr_t dst_xp,
485                             xptr_t src_xp );
486
487/*********************************************************************************************
488 * This function checks the current number of open files for a given process.
489 * It can be called by any thread in any cluster, because it uses portable remote access
490 * primitives to access the reference process descriptor.
491 * It does not take the lock protecting the reference fd_array.
492 *********************************************************************************************
493 * @ returns true if file descriptor array full.
494 ********************************************************************************************/
495bool_t process_fd_array_full( void );
496
497
498
499/********************   Thread Related Operations   *****************************************/
500
501/*********************************************************************************************
502 * This function atomically registers a new thread in the local process descriptor.
503 * It checks that there is an available slot in the local th_tbl[] array, and allocates
504 * a new LTID using the relevant lock depending on the kernel/user type.
505 *********************************************************************************************
506 * @ process  : pointer on the local process descriptor.
507 * @ thread   : pointer on new thread to be registered.
508 * @ trdid    : [out] buffer for allocated trdid.
509 * @ returns 0 if success / returns non zero if no slot available.
510 ********************************************************************************************/
511error_t process_register_thread( process_t       * process,
512                                 struct thread_s * thread,
513                                 trdid_t         * trdid );
514
515
516/***************   Terminals related operations  ********************************************/
517
518/*********************************************************************************************
519 * This function scan the set of user TXT terminals to find a free terminal
520 * (the list of attached processes is empty for a free TXT terminal).
521 * It is called only by the process_reference_init() function when creating a KSH process.
522 * It makes a kernel panic if no free TXT terminal is found.
523 * The allocated TXT terminal is only released when the KSH process is deleted.
524 *********************************************************************************************
525 * @ return TXT terminal index if succes / kernel panic if no terminal found.
526 ********************************************************************************************/
527uint32_t process_txt_alloc( void );
528
529/*********************************************************************************************
530 * This function attach a process, identified by the <process> argument to a TXT terminal,
531 * identified by the <txt_id> channel index argument.
532 * The process descriptor identified by the <process> argument must be in the owner cluster. 
533 * It insert the process descriptor in the xlist rooted in the TXT_RX device.
534 * It is called by the process_reference_init() function.
535 *********************************************************************************************
536 * @ process  : local pointer on process descriptor.
537 * @ txt_id   : TXT channel index.
538 ********************************************************************************************/
539void process_txt_attach( process_t * process,
540                         uint32_t    txt_id );
541
542/*********************************************************************************************
543 * This function detach a process, identified by the <process_xp> argument,
544 * from the list of process attached to a given TXT terminal. It transfer the TXT ownership
545 * to another process, if the detached process is the TXT owner.
546 * The process descriptor identified by the <process_xp> argument must be in the owner
547 * cluster, but the calling thread can be running in any cluster.
548 *********************************************************************************************
549 * @ process_xp  : extended pointer on process descriptor.
550 ********************************************************************************************/
551void process_txt_detach( xptr_t  process_xp );                     
552
553/*********************************************************************************************
554 * This function gives a process identified by the <process_xp> argument the exclusive
555 * ownership of its attached TXT_RX terminal (i.e. put the process in foreground).
556 * It can be called by a thread running in any cluster, but the <process_xp> must be the
557 * owner cluster process descriptor.
558 *********************************************************************************************
559 * @ owner_xp  : extended pointer on process descriptor in owner cluster.
560 ********************************************************************************************/
561void process_txt_set_ownership( xptr_t process_xp );
562
563/*********************************************************************************************
564 * When the process identified by the <owner_xp> argument has the exclusive ownership of
565 * the TXT_RX terminal, this function transfer this ownership to another attached process.
566 * The process descriptor must be the process owner.
567 * This function does nothing if the process identified by the <process_xp> is not
568 * the TXT owner.
569 * - If the current owner is not the KSH process, the new owner is the KSH process.
570 * - If the current owner is the KSH process, the new owner is another attached process.
571 * - If there is no other attached process, the TXT has no more defined owner.
572 *********************************************************************************************
573 * @ process_xp  : extended pointer on process descriptor in owner cluster.
574 ********************************************************************************************/
575void process_txt_transfer_ownership( xptr_t process_xp );
576
577/*********************************************************************************************
578 * This function returns true if the  process identified by the <process_xp> argument
579 * is the TXT owner. It can be called by a thread running in any cluster, but the
580 * process_xp must be the owner cluster process descriptor.
581 *********************************************************************************************
582 * @ returns true if target process is TXT owner.
583 ********************************************************************************************/
584bool_t process_txt_is_owner( xptr_t process_xp );
585
586/*********************************************************************************************
587 * This function returns an extended ponter on the current TXT owner process,
588 * for the TXT terminal identified by the <channel> index.
589 *********************************************************************************************
590 * @ channel : TXT channel.
591 * @ return extended pointer on TXT owner process.
592 ********************************************************************************************/
593xptr_t process_txt_get_owner( uint32_t channel );
594
595/*********************************************************************************************
596 * This debug function diplays on the kernel terminal the list of processes attached
597 * to a given terminal identified by the <txt_id> argument.
598 *********************************************************************************************
599 * @ txt_id  : TXT terminal channel.
600 ********************************************************************************************/
601void process_txt_display( uint32_t txt_id );
602
603
604#endif  /* _PROCESS_H_ */
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