0,0 → 1,232 |
/* |
* Copyright (c) 2006 Ondrej Palkovsky |
* All rights reserved. |
* |
* Redistribution and use in source and binary forms, with or without |
* modification, are permitted provided that the following conditions |
* are met: |
* |
* - Redistributions of source code must retain the above copyright |
* notice, this list of conditions and the following disclaimer. |
* - Redistributions in binary form must reproduce the above copyright |
* notice, this list of conditions and the following disclaimer in the |
* documentation and/or other materials provided with the distribution. |
* - The name of the author may not be used to endorse or promote products |
* derived from this software without specific prior written permission. |
* |
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
*/ |
|
/** @addtogroup genericipc |
* @{ |
*/ |
/** @file |
*/ |
|
/* IPC resources management |
* |
* The goal of this source code is to properly manage IPC resources and allow |
* straight and clean clean-up procedure upon task termination. |
* |
* The pattern of usage of the resources is: |
* - allocate empty phone slot, connect | deallocate slot |
* - disconnect connected phone (some messages might be on the fly) |
* - find phone in slot and send a message using phone |
* - answer message to phone |
* - hangup phone (the caller has hung up) |
* - hangup phone (the answerbox is exiting) |
* |
* Locking strategy |
* |
* - To use a phone, disconnect a phone etc., the phone must be first locked and |
* then checked that it is connected |
* - To connect an allocated phone it need not be locked (assigning pointer is |
* atomic on all platforms) |
* |
* - To find an empty phone slot, the TASK must be locked |
* - To answer a message, the answerbox must be locked |
* - The locking of phone and answerbox is done at the ipc_ level. |
* It is perfectly correct to pass unconnected phone to these functions and |
* proper reply will be generated. |
* |
* Locking order |
* |
* - first phone, then answerbox |
* + Easy locking on calls |
* - Very hard traversing list of phones when disconnecting because the phones |
* may disconnect during traversal of list of connected phones. The only |
* possibility is try_lock with restart of list traversal. |
* |
* Destroying is less frequent, this approach is taken. |
* |
* Phone call |
* |
* *** Connect_me_to *** |
* The caller sends IPC_M_CONNECT_ME_TO to an answerbox. The server receives |
* 'phoneid' of the connecting phone as an ARG5. If it answers with RETVAL=0, |
* the phonecall is accepted, otherwise it is refused. |
* |
* *** Connect_to_me *** |
* The caller sends IPC_M_CONNECT_TO_ME. |
* The server receives an automatically opened phoneid. If it accepts |
* (RETVAL=0), it can use the phoneid immediately. |
* Possible race condition can arise, when the client receives messages from new |
* connection before getting response for connect_to_me message. Userspace |
* should implement handshake protocol that would control it. |
* |
* Phone hangup |
* |
* *** The caller hangs up (sys_ipc_hangup) *** |
* - The phone is disconnected (no more messages can be sent over this phone), |
* all in-progress messages are correctly handled. The answerbox receives |
* IPC_M_PHONE_HUNGUP call from the phone that hung up. When all async |
* calls are answered, the phone is deallocated. |
* |
* *** The answerbox hangs up (ipc_answer(EHANGUP)) |
* - The phone is disconnected. EHANGUP response code is sent |
* to the calling task. All new calls through this phone |
* get a EHUNGUP error code, the task is expected to |
* send an sys_ipc_hangup after cleaning up its internal structures. |
* |
* Call forwarding |
* |
* The call can be forwarded, so that the answer to call is passed directly |
* to the original sender. However, this poses special problems regarding |
* routing of hangup messages. |
* |
* sys_ipc_hangup -> IPC_M_PHONE_HUNGUP |
* - this message CANNOT be forwarded |
* |
* EHANGUP during forward |
* - The *forwarding* phone will be closed, EFORWARD is sent to receiver. |
* |
* EHANGUP, ENOENT during forward |
* - EFORWARD is sent to the receiver, ipc_forward returns error code EFORWARD |
* |
* Cleanup strategy |
* |
* 1) Disconnect all our phones ('ipc_phone_hangup'). |
* |
* 2) Disconnect all phones connected to answerbox. |
* |
* 3) Answer all messages in 'calls' and 'dispatched_calls' queues with |
* appropriate error code (EHANGUP, EFORWARD). |
* |
* 4) Wait for all async answers to arrive and dispose of them. |
* |
*/ |
|
#include <synch/spinlock.h> |
#include <ipc/ipc.h> |
#include <arch.h> |
#include <proc/task.h> |
#include <ipc/ipcrsc.h> |
#include <debug.h> |
|
/** Find call_t * in call table according to callid. |
* |
* @todo Some speedup (hash table?) |
* |
* @param callid Userspace hash of the call. Currently it is the call |
* structure kernel address. |
* |
* @return NULL on not found, otherwise pointer to the call |
* structure. |
*/ |
call_t *get_call(unative_t callid) |
{ |
link_t *lst; |
call_t *call, *result = NULL; |
|
spinlock_lock(&TASK->answerbox.lock); |
for (lst = TASK->answerbox.dispatched_calls.next; |
lst != &TASK->answerbox.dispatched_calls; lst = lst->next) { |
call = list_get_instance(lst, call_t, link); |
if ((unative_t) call == callid) { |
result = call; |
break; |
} |
} |
spinlock_unlock(&TASK->answerbox.lock); |
return result; |
} |
|
/** Allocate new phone slot in the current TASK structure. |
* |
* @return New phone handle or -1 if the phone handle limit is |
* exceeded. |
*/ |
int phone_alloc(void) |
{ |
int i; |
|
spinlock_lock(&TASK->lock); |
for (i = 0; i < IPC_MAX_PHONES; i++) { |
if (TASK->phones[i].state == IPC_PHONE_HUNGUP && |
atomic_get(&TASK->phones[i].active_calls) == 0) |
TASK->phones[i].state = IPC_PHONE_FREE; |
|
if (TASK->phones[i].state == IPC_PHONE_FREE) { |
TASK->phones[i].state = IPC_PHONE_CONNECTING; |
break; |
} |
} |
spinlock_unlock(&TASK->lock); |
|
if (i == IPC_MAX_PHONES) |
return -1; |
|
return i; |
} |
|
/** Mark a phone structure free. |
* |
* @param phone Phone structure to be marked free. |
*/ |
static void phone_deallocp(phone_t *phone) |
{ |
ASSERT(phone->state == IPC_PHONE_CONNECTING); |
|
/* atomic operation */ |
phone->state = IPC_PHONE_FREE; |
} |
|
/** Free slot from a disconnected phone. |
* |
* All already sent messages will be correctly processed. |
* |
* @param phoneid Phone handle of the phone to be freed. |
*/ |
void phone_dealloc(int phoneid) |
{ |
phone_deallocp(&TASK->phones[phoneid]); |
} |
|
/** Connect phone to a given answerbox. |
* |
* @param phoneid Phone handle to be connected. |
* @param box Answerbox to which to connect the phone handle. |
* |
* The procedure _enforces_ that the user first marks the phone |
* busy (e.g. via phone_alloc) and then connects the phone, otherwise |
* race condition may appear. |
*/ |
void phone_connect(int phoneid, answerbox_t *box) |
{ |
phone_t *phone = &TASK->phones[phoneid]; |
|
ASSERT(phone->state == IPC_PHONE_CONNECTING); |
ipc_phone_connect(phone, box); |
} |
|
/** @} |
*/ |