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Diffstat (limited to 'usr/src/uts/common/io/ptm.c')
-rw-r--r--usr/src/uts/common/io/ptm.c246
1 files changed, 124 insertions, 122 deletions
diff --git a/usr/src/uts/common/io/ptm.c b/usr/src/uts/common/io/ptm.c
index 472cbf6936..8127d54594 100644
--- a/usr/src/uts/common/io/ptm.c
+++ b/usr/src/uts/common/io/ptm.c
@@ -26,97 +26,107 @@
/*
* Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
+ * Copyright 2021 Oxide Computer Company
*/
/*
- * Pseudo Terminal Master Driver.
+ * PSEUDO-TERMINAL MANAGER DRIVER (PTM)
*
- * The pseudo-tty subsystem simulates a terminal connection, where the master
- * side represents the terminal and the slave represents the user process's
- * special device end point. The master device is set up as a cloned device
- * where its major device number is the major for the clone device and its minor
- * device number is the major for the ptm driver. There are no nodes in the file
- * system for master devices. The master pseudo driver is opened using the
- * open(2) system call with /dev/ptmx as the device parameter. The clone open
- * finds the next available minor device for the ptm major device.
+ * The pseudo-terminal subsystem simulates a terminal connection, where the
+ * manager side represents the terminal and the subsidiary represents the user
+ * process's special device end point. The manager device is set up as a
+ * cloned device where its major device number is the major for the clone
+ * device and its minor device number is the major for the ptm driver. There
+ * are no nodes in the file system for manager devices. The manager pseudo
+ * driver is opened using the open(2) system call with /dev/ptmx as the device
+ * parameter. The clone open finds the next available minor device for the ptm
+ * major device.
*
- * A master device is available only if it and its corresponding slave device
- * are not already open. When the master device is opened, the corresponding
- * slave device is automatically locked out. Only one open is allowed on a
- * master device. Multiple opens are allowed on the slave device. After both
- * the master and slave have been opened, the user has two file descriptors
- * which are the end points of a full duplex connection composed of two streams
- * which are automatically connected at the master and slave drivers. The user
- * may then push modules onto either side of the stream pair.
+ * A manager device is available only if it and its corresponding subsidiary
+ * device are not already open. When the manager device is opened, the
+ * corresponding subsidiary device is automatically locked out. Only one open
+ * is allowed on a manager device. Multiple opens are allowed on the
+ * subsidiary device. After both the manager and subsidiary have been opened,
+ * the user has two file descriptors which are the end points of a full duplex
+ * connection composed of two streams which are automatically connected at the
+ * manager and subsidiary drivers. The user may then push modules onto either
+ * side of the stream pair.
*
- * The master and slave drivers pass all messages to their adjacent queues.
- * Only the M_FLUSH needs some processing. Because the read queue of one side
- * is connected to the write queue of the other, the FLUSHR flag is changed to
- * the FLUSHW flag and vice versa. When the master device is closed an M_HANGUP
- * message is sent to the slave device which will render the device
- * unusable. The process on the slave side gets the EIO when attempting to write
- * on that stream but it will be able to read any data remaining on the stream
- * head read queue. When all the data has been read, read() returns 0
- * indicating that the stream can no longer be used. On the last close of the
- * slave device, a 0-length message is sent to the master device. When the
- * application on the master side issues a read() or getmsg() and 0 is returned,
- * the user of the master device decides whether to issue a close() that
- * dismantles the pseudo-terminal subsystem. If the master device is not closed,
- * the pseudo-tty subsystem will be available to another user to open the slave
- * device.
+ * The manager and subsidiary drivers pass all messages to their adjacent
+ * queues. Only the M_FLUSH needs some processing. Because the read queue of
+ * one side is connected to the write queue of the other, the FLUSHR flag is
+ * changed to the FLUSHW flag and vice versa. When the manager device is
+ * closed an M_HANGUP message is sent to the subsidiary device which will
+ * render the device unusable. The process on the subsidiary side gets an EIO
+ * error when attempting to write on that stream but it will be able to read
+ * any data remaining on the stream head read queue. When all the data has
+ * been read, read() returns 0 indicating that the stream can no longer be
+ * used. On the last close of the subsidiary device, a 0-length message is
+ * sent to the manager device. When the application on the manager side issues
+ * a read() or getmsg() and 0 is returned, the user of the manager device
+ * decides whether to issue a close() that dismantles the pseudo-terminal
+ * subsystem. If the manager device is not closed, the pseudo-terminal
+ * subsystem will be available to another user to open the subsidiary device.
*
- * If O_NONBLOCK or O_NDELAY is set, read on the master side returns -1 with
+ * If O_NONBLOCK or O_NDELAY is set, read on the manager side returns -1 with
* errno set to EAGAIN if no data is available, and write returns -1 with errno
* set to EAGAIN if there is internal flow control.
*
- * IOCTLS:
*
- * ISPTM: determines whether the file descriptor is that of an open master
- * device. Return code of zero indicates that the file descriptor
- * represents master device.
+ * IOCTLS
*
- * UNLKPT: unlocks the master and slave devices. It returns 0 on success. On
- * failure, the errno is set to EINVAL indicating that the master
- * device is not open.
+ * ISPTM
+ * Determines whether the file descriptor is that of an open
+ * manager device. Return code of zero indicates that the file
+ * descriptor represents a manager device.
*
- * ZONEPT: sets the zone membership of the associated pts device.
+ * UNLKPT
+ * Unlocks the manager and subsidiary devices. It returns 0 on
+ * success. On failure, the errno is set to EINVAL indicating that
+ * the manager device is not open.
*
- * GRPPT: sets the group owner of the associated pts device.
+ * ZONEPT
+ * Sets the zone membership of the associated subsidiary device.
*
- * Synchronization:
+ * GRPPT
+ * Sets the group owner of the associated subsidiary device.
*
- * All global data synchronization between ptm/pts is done via global
- * ptms_lock mutex which is initialized at system boot time from
- * ptms_initspace (called from space.c).
*
- * Individual fields of pt_ttys structure (except ptm_rdq, pts_rdq and
- * pt_nullmsg) are protected by pt_ttys.pt_lock mutex.
+ * SYNCHRONIZATION
*
- * PT_ENTER_READ/PT_ENTER_WRITE are reference counter based read-write locks
- * which allow reader locks to be reacquired by the same thread (usual
- * reader/writer locks can't be used for that purpose since it is illegal for
- * a thread to acquire a lock it already holds, even as a reader). The sole
- * purpose of these macros is to guarantee that the peer queue will not
- * disappear (due to closing peer) while it is used. It is safe to use
- * PT_ENTER_READ/PT_EXIT_READ brackets across calls like putq/putnext (since
- * they are not real locks but reference counts).
+ * All global data synchronization between ptm/pts is done via global ptms_lock
+ * mutex which is initialized at system boot time from ptms_initspace (called
+ * from space.c).
*
- * PT_ENTER_WRITE/PT_EXIT_WRITE brackets are used ONLY in master/slave
- * open/close paths to modify ptm_rdq and pts_rdq fields. These fields should
- * be set to appropriate queues *after* qprocson() is called during open (to
- * prevent peer from accessing the queue with incomplete plumbing) and set to
- * NULL before qprocsoff() is called during close.
+ * Individual fields of pt_ttys structure (except ptm_rdq, pts_rdq and
+ * pt_nullmsg) are protected by pt_ttys.pt_lock mutex.
*
- * The pt_nullmsg field is only used in open/close routines and it is also
- * protected by PT_ENTER_WRITE/PT_EXIT_WRITE brackets to avoid extra mutex
- * holds.
+ * PT_ENTER_READ/PT_ENTER_WRITE are reference counter based read-write locks
+ * which allow reader locks to be reacquired by the same thread (usual
+ * reader/writer locks can't be used for that purpose since it is illegal for a
+ * thread to acquire a lock it already holds, even as a reader). The sole
+ * purpose of these macros is to guarantee that the peer queue will not
+ * disappear (due to closing peer) while it is used. It is safe to use
+ * PT_ENTER_READ/PT_EXIT_READ brackets across calls like putq/putnext (since
+ * they are not real locks but reference counts).
*
- * Lock Ordering:
+ * PT_ENTER_WRITE/PT_EXIT_WRITE brackets are used ONLY in manager/subsidiary
+ * open/close paths to modify ptm_rdq and pts_rdq fields. These fields should
+ * be set to appropriate queues *after* qprocson() is called during open (to
+ * prevent peer from accessing the queue with incomplete plumbing) and set to
+ * NULL before qprocsoff() is called during close.
*
- * If both ptms_lock and per-pty lock should be held, ptms_lock should always
- * be entered first, followed by per-pty lock.
+ * The pt_nullmsg field is only used in open/close routines and it is also
+ * protected by PT_ENTER_WRITE/PT_EXIT_WRITE brackets to avoid extra mutex
+ * holds.
*
- * See ptms.h, pts.c and ptms_conf.c for more information.
+ *
+ * LOCK ORDERING
+ *
+ * If both ptms_lock and per-pty lock should be held, ptms_lock should always
+ * be entered first, followed by per-pty lock.
+ *
+ * See ptms.h, pts.c, and ptms_conf.c for more information.
*/
#include <sys/types.h>
@@ -152,10 +162,6 @@ static int ptmwput(queue_t *, mblk_t *);
static int ptmrsrv(queue_t *);
static int ptmwsrv(queue_t *);
-/*
- * Master Stream Pseudo Terminal Module: stream data structure definitions
- */
-
static struct module_info ptm_info = {
0xdead,
"ptm",
@@ -209,9 +215,9 @@ DDI_DEFINE_STREAM_OPS(ptm_ops, nulldev, nulldev, ptm_attach, ptm_detach,
*/
static struct modldrv modldrv = {
- &mod_driverops, /* Type of module. This one is a pseudo driver */
- "Master streams driver 'ptm'",
- &ptm_ops, /* driver ops */
+ &mod_driverops,
+ "Pseudo-Terminal Manager Driver",
+ &ptm_ops,
};
static struct modlinkage modlinkage = {
@@ -273,7 +279,6 @@ ptm_detach(dev_info_t *devi, ddi_detach_cmd_t cmd)
return (DDI_SUCCESS);
}
-/*ARGSUSED*/
static int
ptm_devinfo(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg,
void **result)
@@ -300,12 +305,11 @@ ptm_devinfo(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg,
}
-/* ARGSUSED */
/*
- * Open a minor of the master device. Store the write queue pointer and set the
- * pt_state field to (PTMOPEN | PTLOCK).
+ * Open a minor of the manager device. Store the write queue pointer and set
+ * the pt_state field to (PTMOPEN | PTLOCK).
* This code will work properly with both clone opens and direct opens of the
- * master device.
+ * manager device.
*/
static int
ptmopen(
@@ -329,19 +333,18 @@ ptmopen(
if (!(sflag & CLONEOPEN) && dminor != 0) {
/*
- * This is a direct open to specific master device through an
+ * This is a direct open to specific manager device through an
* artificially created entry with specific minor in
- * /dev/directory. Such behavior is not supported.
+ * /dev/directory. Such behavior is not supported.
*/
return (ENXIO);
}
/*
- * The master open requires that the slave be attached
- * before it returns so that attempts to open the slave will
- * succeeed
+ * The manager open requires that the subsidiary be attached before it
+ * returns so that attempts to open the subsidiary will succeeed
*/
- if (ptms_attach_slave() != 0) {
+ if (ptms_attach_subsidiary() != 0) {
return (ENXIO);
}
@@ -366,7 +369,7 @@ ptmopen(
qprocson(rqp);
- /* Allow slave to send messages to master */
+ /* Allow subsidiary to send messages to manager */
PT_ENTER_WRITE(ptmp);
ptmp->ptm_rdq = rqp;
PT_EXIT_WRITE(ptmp);
@@ -397,13 +400,12 @@ ptmopen(
/*
- * Find the address to private data identifying the slave's write queue.
- * Send a hang-up message up the slave's read queue to designate the
- * master/slave pair is tearing down. Uattach the master and slave by
- * nulling out the write queue fields in the private data structure.
- * Finally, unlock the master/slave pair and mark the master as closed.
+ * Find the address to private data identifying the subsidiary's write queue.
+ * Send a hang-up message up the subsidiary's read queue to designate the
+ * manager/subsidiary pair is tearing down. Uattach the manager and subsidiary
+ * by nulling out the write queue fields in the private data structure.
+ * Finally, unlock the manager/subsidiary pair and mark the manager as closed.
*/
-/*ARGSUSED1*/
static int
ptmclose(queue_t *rqp, int flag, cred_t *credp)
{
@@ -417,7 +419,7 @@ ptmclose(queue_t *rqp, int flag, cred_t *credp)
if (ptmp->pts_rdq) {
pts_rdq = ptmp->pts_rdq;
if (pts_rdq->q_next) {
- DBG(("send hangup message to slave\n"));
+ DBG(("send hangup message to subsidiary\n"));
(void) putnextctl(pts_rdq, M_HANGUP);
}
}
@@ -431,8 +433,8 @@ ptmclose(queue_t *rqp, int flag, cred_t *credp)
freemsg(ptmp->pt_nullmsg);
ptmp->pt_nullmsg = NULL;
/*
- * qenable slave side write queue so that it can flush
- * its messages as master's read queue is going away
+ * qenable subsidiary side write queue so that it can flush
+ * its messages as manager's read queue is going away
*/
if (ptmp->pts_rdq)
qenable(WR(ptmp->pts_rdq));
@@ -466,9 +468,9 @@ ptmwput(queue_t *qp, mblk_t *mp)
switch (mp->b_datap->db_type) {
/*
- * if write queue request, flush master's write
- * queue and send FLUSHR up slave side. If read
- * queue request, convert to FLUSHW and putnext().
+ * If this is a write queue request, flush manager's write queue and
+ * send FLUSHR up subsidiary side. If it is a read queue request,
+ * convert to FLUSHW and putnext().
*/
case M_FLUSH:
{
@@ -477,14 +479,15 @@ ptmwput(queue_t *qp, mblk_t *mp)
DBG(("ptm got flush request\n"));
if (*mp->b_rptr & FLUSHW) {
DBG(("got FLUSHW, flush ptm write Q\n"));
- if (*mp->b_rptr & FLUSHBAND)
+ if (*mp->b_rptr & FLUSHBAND) {
/*
* if it is a FLUSHBAND, do flushband.
*/
flushband(qp, *(mp->b_rptr + 1),
FLUSHDATA);
- else
+ } else {
flushq(qp, FLUSHDATA);
+ }
flush_flg = (*mp->b_rptr & ~FLUSHW) | FLUSHR;
}
if (*mp->b_rptr & FLUSHR) {
@@ -496,8 +499,9 @@ ptmwput(queue_t *qp, mblk_t *mp)
DBG(("putnext to pts\n"));
*mp->b_rptr = flush_flg;
putnext(ptmp->pts_rdq, mp);
- } else
+ } else {
freemsg(mp);
+ }
break;
}
@@ -507,7 +511,7 @@ ptmwput(queue_t *qp, mblk_t *mp)
default:
if ((ptmp->pt_state & PTLOCK) ||
(ptmp->pts_rdq == NULL)) {
- DBG(("got M_IOCTL but no slave\n"));
+ DBG(("got M_IOCTL but no subsidiary\n"));
miocnak(qp, mp, 0, EINVAL);
PT_EXIT_READ(ptmp);
return (0);
@@ -587,16 +591,16 @@ ptmwput(queue_t *qp, mblk_t *mp)
break;
case M_READ:
- /* Caused by ldterm - can not pass to slave */
+ /* Caused by ldterm - can not pass to subsidiary */
freemsg(mp);
break;
/*
- * send other messages to slave
+ * Send other messages to the subsidiary:
*/
default:
- if ((ptmp->pt_state & PTLOCK) || (ptmp->pts_rdq == NULL)) {
- DBG(("got msg. but no slave\n"));
+ if ((ptmp->pt_state & PTLOCK) || (ptmp->pts_rdq == NULL)) {
+ DBG(("got msg. but no subsidiary\n"));
mp = mexchange(NULL, mp, 2, M_ERROR, -1);
if (mp != NULL) {
mp->b_rptr[0] = NOERROR;
@@ -606,7 +610,7 @@ ptmwput(queue_t *qp, mblk_t *mp)
PT_EXIT_READ(ptmp);
return (0);
}
- DBG(("put msg on master's write queue\n"));
+ DBG(("put msg on manager's write queue\n"));
(void) putq(qp, mp);
break;
}
@@ -617,9 +621,8 @@ ptmwput(queue_t *qp, mblk_t *mp)
/*
- * enable the write side of the slave. This triggers the
- * slave to send any messages queued on its write side to
- * the read side of this master.
+ * Enable the write side of the subsidiary. This triggers the subsidiary to
+ * send any messages queued on its write side to the read side of this manager.
*/
static int
ptmrsrv(queue_t *qp)
@@ -641,10 +644,10 @@ ptmrsrv(queue_t *qp)
/*
- * If there are messages on this queue that can be sent to
- * slave, send them via putnext(). Else, if queued messages
- * cannot be sent, leave them on this queue. If priority
- * messages on this queue, send them to slave no matter what.
+ * If there are messages on this queue that can be sent to subsidiary, send
+ * them via putnext(). Otherwise, if queued messages cannot be sent, leave
+ * them on this queue. If priority messages on this queue, send them to the
+ * subsidiary no matter what.
*/
static int
ptmwsrv(queue_t *qp)
@@ -665,7 +668,7 @@ ptmwsrv(queue_t *qp)
PT_ENTER_READ(ptmp);
if ((ptmp->pt_state & PTLOCK) || (ptmp->pts_rdq == NULL)) {
- DBG(("in master write srv proc but no slave\n"));
+ DBG(("in manager write srv proc but no subsidiary\n"));
/*
* Free messages on the write queue and send
* NAK for any M_IOCTL type messages to wakeup
@@ -690,13 +693,12 @@ ptmwsrv(queue_t *qp)
return (0);
}
/*
- * while there are messages on this write queue...
+ * While there are messages on this write queue...
*/
do {
/*
- * if don't have control message and cannot put
- * msg. on slave's read queue, put it back on
- * this queue.
+ * If this is not a control message, and we cannot put messages
+ * on the subsidiary's read queue, put it back on this queue.
*/
if (mp->b_datap->db_type <= QPCTL &&
!bcanputnext(ptmp->pts_rdq, mp->b_band)) {
@@ -705,9 +707,9 @@ ptmwsrv(queue_t *qp)
break;
}
/*
- * else send the message up slave's stream
+ * Otherwise send the message up subsidiary's stream
*/
- DBG(("send message to slave\n"));
+ DBG(("send message to subsidiary\n"));
putnext(ptmp->pts_rdq, mp);
} while ((mp = getq(qp)) != NULL);
DBG(("leaving ptmwsrv\n"));
generated by cgit v1.2.3 (git 2.46.0) at 2025-12-05 13:47:15 +0000