b4d909d415
This patch separates the character and block driver communication protocols. The old character protocol remains the same, but a new block protocol is introduced. The libdriver library is replaced by two new libraries: libchardriver and libblockdriver. Their exposed API, and drivers that use them, have been updated accordingly. Together, libbdev and libblockdriver now completely abstract away the message format used by the block protocol. As the memory driver is both a character and a block device driver, it now implements its own message loop. The most important semantic change made to the block protocol is that it is no longer possible to return both partial results and an error for a single transfer. This simplifies the interaction between the caller and the driver, as the I/O vector no longer needs to be copied back. Also, drivers are now no longer supposed to decide based on the layout of the I/O vector when a transfer should be cut short. Put simply, transfers are now supposed to either succeed completely, or result in an error. After this patch, the state of the various pieces is as follows: - block protocol: stable - libbdev API: stable for synchronous communication - libblockdriver API: needs slight revision (the drvlib/partition API in particular; the threading API will also change shortly) - character protocol: needs cleanup - libchardriver API: needs cleanup accordingly - driver restarts: largely unsupported until endpoint changes are reintroduced As a side effect, this patch eliminates several bugs, hacks, and gcc -Wall and -W warnings all over the place. It probably introduces a few new ones, too. Update warning: this patch changes the protocol between MFS and disk drivers, so in order to use old/new images, the MFS from the ramdisk must be used to mount all file systems.
468 lines
15 KiB
C
468 lines
15 KiB
C
/* This file contains the device independent character driver interface.
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*
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* The drivers support the following operations (using message format m2):
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*
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* m_type DEVICE USER_ENDPT COUNT POSITION HIGHPOS IO_GRANT
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* ----------------------------------------------------------------------------
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* | DEV_OPEN | device | proc nr | mode | | | |
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* |---------------+--------+---------+---------+--------+--------+-----------|
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* | DEV_CLOSE | device | proc nr | | | | |
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* |---------------+--------+---------+---------+--------+--------+-----------|
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* | DEV_READ_S | device | proc nr | bytes | off lo | off hi i buf grant |
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* |---------------+--------+---------+---------+--------+--------+-----------|
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* | DEV_WRITE_S | device | proc nr | bytes | off lo | off hi | buf grant |
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* |---------------+--------+---------+---------+--------+--------+-----------|
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* | DEV_GATHER_S | device | proc nr | iov len | off lo | off hi | iov grant |
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* |---------------+--------+---------+---------+--------+--------+-----------|
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* | DEV_SCATTER_S | device | proc nr | iov len | off lo | off hi | iov grant |
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* |---------------+--------+---------+---------+--------+--------+-----------|
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* | DEV_IOCTL_S | device | proc nr | request | | | buf grant |
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* |---------------+--------+---------+---------+--------+--------+-----------|
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* | CANCEL | device | proc nr | r/w | | | grant |
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* |---------------+--------+---------+---------+--------+--------+-----------|
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* | DEV_SELECT | device | ops | | | | |
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* ----------------------------------------------------------------------------
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*
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* The entry points into this file are:
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* driver_task: the main message loop of the driver
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* driver_receive: message receive interface for drivers
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*
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* Changes:
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* Oct 16, 2011 split character and block protocol (D.C. van Moolenbroek)
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* Aug 27, 2011 move common functions into driver.c (A. Welzel)
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* Jul 25, 2005 added SYS_SIG type for signals (Jorrit N. Herder)
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* Sep 15, 2004 added SYN_ALARM type for timeouts (Jorrit N. Herder)
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* Jul 23, 2004 removed kernel dependencies (Jorrit N. Herder)
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* Apr 02, 1992 constructed from AT wini and floppy driver (Kees J. Bot)
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*/
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#include <minix/drivers.h>
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#include <minix/chardriver.h>
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#include <minix/ds.h>
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PRIVATE int running;
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/* Management data for opened devices. */
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PRIVATE int open_devs[MAX_NR_OPEN_DEVICES];
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PRIVATE int next_open_devs_slot = 0;
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/*===========================================================================*
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* clear_open_devs *
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*===========================================================================*/
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PRIVATE void clear_open_devs(void)
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{
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/* Reset the set of previously opened minor devices. */
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next_open_devs_slot = 0;
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}
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/*===========================================================================*
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* is_open_dev *
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*===========================================================================*/
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PRIVATE int is_open_dev(int device)
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{
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/* Check whether the given minor device has previously been opened. */
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int i;
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for (i = 0; i < next_open_devs_slot; i++)
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if (open_devs[i] == device)
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return TRUE;
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return FALSE;
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}
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/*===========================================================================*
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* set_open_dev *
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*===========================================================================*/
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PRIVATE void set_open_dev(int device)
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{
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/* Mark the given minor device as having been opened. */
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if (next_open_devs_slot >= MAX_NR_OPEN_DEVICES)
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panic("out of slots for open devices");
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open_devs[next_open_devs_slot] = device;
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next_open_devs_slot++;
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}
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/*===========================================================================*
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* chardriver_announce *
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*===========================================================================*/
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PUBLIC void chardriver_announce(void)
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{
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/* Announce we are up after a fresh start or restart. */
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int r;
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char key[DS_MAX_KEYLEN];
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char label[DS_MAX_KEYLEN];
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char *driver_prefix = "drv.chr.";
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/* Callers are allowed to use sendrec to communicate with drivers.
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* For this reason, there may blocked callers when a driver restarts.
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* Ask the kernel to unblock them (if any).
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*/
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#if USE_STATECTL
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if ((r = sys_statectl(SYS_STATE_CLEAR_IPC_REFS)) != OK)
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panic("chardriver_init: sys_statectl failed: %d", r);
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#endif
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/* Publish a driver up event. */
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if ((r = ds_retrieve_label_name(label, getprocnr())) != OK)
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panic("chardriver_init: unable to get own label: %d", r);
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snprintf(key, DS_MAX_KEYLEN, "%s%s", driver_prefix, label);
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if ((r = ds_publish_u32(key, DS_DRIVER_UP, DSF_OVERWRITE)) != OK)
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panic("chardriver_init: unable to publish driver up event: %d", r);
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/* Expect a DEV_OPEN for any device before serving regular driver requests. */
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clear_open_devs();
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}
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/*===========================================================================*
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* async_reply *
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*===========================================================================*/
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PRIVATE void async_reply(message *mess, int r)
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{
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/* Send a reply using the asynchronous character device protocol. */
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message reply_mess;
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/* Do not reply with ERESTART in this protocol. The only possible caller,
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* VFS, will find out through other means when we have restarted, and is not
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* (fully) ready to deal with ERESTART errors.
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*/
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if (r == ERESTART)
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return;
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switch (mess->m_type) {
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case DEV_OPEN:
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reply_mess.m_type = DEV_REVIVE;
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reply_mess.REP_ENDPT = mess->USER_ENDPT;
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reply_mess.REP_STATUS = r;
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break;
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case DEV_CLOSE:
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reply_mess.m_type = DEV_CLOSE_REPL;
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reply_mess.REP_ENDPT = mess->USER_ENDPT;
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reply_mess.REP_STATUS = r;
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break;
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case DEV_READ_S:
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case DEV_WRITE_S:
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case DEV_IOCTL_S:
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if (r == SUSPEND)
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printf("driver_task: reviving %d (%d) with SUSPEND\n",
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mess->m_source, mess->USER_ENDPT);
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reply_mess.m_type = DEV_REVIVE;
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reply_mess.REP_ENDPT = mess->USER_ENDPT;
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reply_mess.REP_IO_GRANT = (cp_grant_id_t) mess->IO_GRANT;
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reply_mess.REP_STATUS = r;
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break;
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case CANCEL:
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/* The original request should send a reply. */
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return;
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case DEV_SELECT:
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reply_mess.m_type = DEV_SEL_REPL1;
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reply_mess.DEV_MINOR = mess->DEVICE;
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reply_mess.DEV_SEL_OPS = r;
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break;
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default:
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reply_mess.m_type = TASK_REPLY;
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reply_mess.REP_ENDPT = mess->USER_ENDPT;
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/* Status is # of bytes transferred or error code. */
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reply_mess.REP_STATUS = r;
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break;
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}
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r = asynsend(mess->m_source, &reply_mess);
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if (r != OK)
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printf("asyn_reply: unable to asynsend reply to %d: %d\n",
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mess->m_source, r);
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}
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/*===========================================================================*
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* sync_reply *
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*===========================================================================*/
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PRIVATE void sync_reply(message *m_ptr, int ipc_status, int reply)
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{
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/* Reply to a message sent to the driver. */
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endpoint_t caller_e, user_e;
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int r;
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caller_e = m_ptr->m_source;
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user_e = m_ptr->USER_ENDPT;
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m_ptr->m_type = TASK_REPLY;
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m_ptr->REP_ENDPT = user_e;
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m_ptr->REP_STATUS = reply;
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/* If we would block sending the message, send it asynchronously. */
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if (IPC_STATUS_CALL(ipc_status) == SENDREC)
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r = sendnb(caller_e, m_ptr);
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else
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r = asynsend(caller_e, m_ptr);
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if (r != OK)
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printf("driver_reply: unable to send reply to %d: %d\n", caller_e, r);
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}
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/*===========================================================================*
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* send_reply *
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*===========================================================================*/
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PRIVATE void send_reply(int type, message *m_ptr, int ipc_status, int reply)
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{
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/* Prepare and send a reply message. */
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if (reply == EDONTREPLY)
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return;
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if (type == CHARDRIVER_ASYNC)
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async_reply(m_ptr, reply);
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else
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sync_reply(m_ptr, ipc_status, reply);
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}
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/*===========================================================================*
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* do_rdwt *
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*===========================================================================*/
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PRIVATE int do_rdwt(struct chardriver *cdp, message *mp)
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{
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/* Carry out a single read or write request. */
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iovec_t iovec1;
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int r, opcode;
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u64_t position;
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/* Disk address? Address and length of the user buffer? */
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if (mp->COUNT < 0) return(EINVAL);
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/* Prepare for I/O. */
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if ((*cdp->cdr_prepare)(mp->DEVICE) == NULL) return(ENXIO);
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/* Create a one element scatter/gather vector for the buffer. */
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if(mp->m_type == DEV_READ_S) opcode = DEV_GATHER_S;
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else opcode = DEV_SCATTER_S;
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iovec1.iov_addr = (vir_bytes) mp->IO_GRANT;
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iovec1.iov_size = mp->COUNT;
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/* Transfer bytes from/to the device. */
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position= make64(mp->POSITION, mp->HIGHPOS);
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r = (*cdp->cdr_transfer)(mp->m_source, opcode, position, &iovec1, 1,
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mp->USER_ENDPT);
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/* Return the number of bytes transferred or an error code. */
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return(r == OK ? (int) (mp->COUNT - iovec1.iov_size) : r);
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}
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/*===========================================================================*
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* do_vrdwt *
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*===========================================================================*/
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PRIVATE int do_vrdwt(struct chardriver *cdp, message *mp)
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{
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/* Carry out an device read or write to/from a vector of user addresses.
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* The "user addresses" are assumed to be safe, i.e. FS transferring to/from
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* its own buffers, so they are not checked.
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*/
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iovec_t iovec[NR_IOREQS];
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phys_bytes iovec_size;
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unsigned nr_req;
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int r, opcode;
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u64_t position;
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nr_req = mp->COUNT; /* Length of I/O vector */
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/* Copy the vector from the caller to kernel space. */
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if (nr_req > NR_IOREQS) nr_req = NR_IOREQS;
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iovec_size = (phys_bytes) (nr_req * sizeof(iovec[0]));
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if (OK != sys_safecopyfrom(mp->m_source, (vir_bytes) mp->IO_GRANT,
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0, (vir_bytes) iovec, iovec_size, D)) {
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printf("bad I/O vector by: %d\n", mp->m_source);
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return(EINVAL);
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}
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/* Prepare for I/O. */
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if ((*cdp->cdr_prepare)(mp->DEVICE) == NULL) return(ENXIO);
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/* Transfer bytes from/to the device. */
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opcode = mp->m_type;
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position= make64(mp->POSITION, mp->HIGHPOS);
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r = (*cdp->cdr_transfer)(mp->m_source, opcode, position, iovec, nr_req,
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mp->USER_ENDPT);
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/* Copy the I/O vector back to the caller. */
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if (OK != sys_safecopyto(mp->m_source, (vir_bytes) mp->IO_GRANT,
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0, (vir_bytes) iovec, iovec_size, D)) {
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printf("couldn't return I/O vector: %d\n", mp->m_source);
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return(EINVAL);
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}
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return(r);
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}
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/*===========================================================================*
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* handle_notify *
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*===========================================================================*/
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PRIVATE void handle_notify(struct chardriver *cdp, message *m_ptr)
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{
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/* Take care of the notifications (interrupt and clock messages) by calling the
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* appropiate callback functions. Never send a reply.
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*/
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/* Call the appropriate function for this notification. */
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switch (_ENDPOINT_P(m_ptr->m_source)) {
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case CLOCK:
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if (cdp->cdr_alarm)
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cdp->cdr_alarm(m_ptr);
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break;
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default:
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if (cdp->cdr_other)
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(void) cdp->cdr_other(m_ptr);
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}
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}
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/*===========================================================================*
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* handle_request *
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*===========================================================================*/
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PRIVATE int handle_request(struct chardriver *cdp, message *m_ptr)
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{
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/* Call the appropiate driver function, based on the type of request. Return
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* the result code that is to be sent back to the caller, or EDONTREPLY if no
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* reply is to be sent.
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*/
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int r;
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/* We might get spurious requests if the driver has been restarted. Deny any
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* requests on devices that have not previously been opened, signaling the
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* caller that something went wrong.
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*/
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if (IS_CDEV_MINOR_RQ(m_ptr->m_type) && !is_open_dev(m_ptr->DEVICE)) {
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/* Reply ERESTART to spurious requests for unopened devices. */
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if (m_ptr->m_type != DEV_OPEN)
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return ERESTART;
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/* Mark the device as opened otherwise. */
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set_open_dev(m_ptr->DEVICE);
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}
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/* Call the appropriate function(s) for this request. */
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switch (m_ptr->m_type) {
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case DEV_OPEN: r = (*cdp->cdr_open)(m_ptr); break;
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case DEV_CLOSE: r = (*cdp->cdr_close)(m_ptr); break;
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case DEV_IOCTL_S: r = (*cdp->cdr_ioctl)(m_ptr); break;
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case CANCEL: r = (*cdp->cdr_cancel)(m_ptr); break;
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case DEV_SELECT: r = (*cdp->cdr_select)(m_ptr); break;
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case DEV_READ_S:
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case DEV_WRITE_S: r = do_rdwt(cdp, m_ptr); break;
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case DEV_GATHER_S:
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case DEV_SCATTER_S: r = do_vrdwt(cdp, m_ptr); break;
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default:
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if (cdp->cdr_other)
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r = cdp->cdr_other(m_ptr);
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else
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r = EINVAL;
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}
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/* Let the driver perform any cleanup. */
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if (cdp->cdr_cleanup)
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(*cdp->cdr_cleanup)();
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return r;
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}
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/*===========================================================================*
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* chardriver_process *
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*===========================================================================*/
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PUBLIC void chardriver_process(struct chardriver *cdp, int driver_type,
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message *m_ptr, int ipc_status)
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{
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/* Handle the given received message. */
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int r;
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/* Process the notification or request. */
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if (is_ipc_notify(ipc_status)) {
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handle_notify(cdp, m_ptr);
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/* Do not reply to notifications. */
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} else {
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r = handle_request(cdp, m_ptr);
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send_reply(driver_type, m_ptr, ipc_status, r);
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}
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}
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/*===========================================================================*
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* chardriver_task *
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*===========================================================================*/
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PUBLIC void chardriver_task(struct chardriver *cdp, int driver_type)
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{
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/* Main program of any device driver task. */
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int r, ipc_status;
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message mess;
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running = TRUE;
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/* Here is the main loop of the disk task. It waits for a message, carries
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* it out, and sends a reply.
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*/
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while (running) {
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if ((r = sef_receive_status(ANY, &mess, &ipc_status)) != OK)
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panic("driver_receive failed: %d", r);
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chardriver_process(cdp, driver_type, &mess, ipc_status);
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}
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}
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/*===========================================================================*
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* do_nop *
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*===========================================================================*/
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PUBLIC int do_nop(message *UNUSED(mp))
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{
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return(OK);
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}
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/*===========================================================================*
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* nop_ioctl *
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*===========================================================================*/
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PUBLIC int nop_ioctl(message *UNUSED(mp))
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{
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return(ENOTTY);
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}
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/*===========================================================================*
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* nop_alarm *
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*===========================================================================*/
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PUBLIC void nop_alarm(message *UNUSED(mp))
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{
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/* Ignore the leftover alarm. */
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}
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/*===========================================================================*
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* nop_cleanup *
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*===========================================================================*/
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PUBLIC void nop_cleanup(void)
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{
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/* Nothing to clean up. */
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}
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/*===========================================================================*
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* nop_cancel *
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*===========================================================================*/
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PUBLIC int nop_cancel(message *UNUSED(m))
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{
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/* Nothing to do for cancel. */
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return(OK);
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}
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/*===========================================================================*
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* nop_select *
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*===========================================================================*/
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PUBLIC int nop_select(message *UNUSED(m))
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{
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/* Nothing to do for select. */
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return(OK);
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}
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