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14249 pseudo-terminal nomenclature should reflect POSIX
Change-Id: Ib4a3cef899ff4c71b09cb0dc6878863c5e8357bc
*** 19,79 ****
* CDDL HEADER END
*/
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/*
! * This file contains global data and code shared between master and slave parts
! * of the pseudo-terminal driver.
*
! * Pseudo terminals (or pt's for short) are allocated dynamically.
! * pt's are put in the global ptms_slots array indexed by minor numbers.
*
! * The slots array is initially small (of the size NPTY_MIN). When more pt's are
* needed than the slot array size, the larger slot array is allocated and all
! * opened pt's move to the new one.
*
- * Resource allocation:
*
! * pt_ttys structures are allocated via pt_ttys_alloc, which uses
* kmem_cache_alloc().
! * Minor number space is allocated via vmem_alloc() interface.
! * ptms_slots arrays are allocated via kmem_alloc().
*
! * Minors are started from 1 instead of 0 because vmem_alloc returns 0 in case
! * of failure. Also, in anticipation of removing clone device interface to
* pseudo-terminal subsystem, minor 0 should not be used. (Potential future
* development).
*
* After the table slot size reaches pt_maxdelta, we stop 2^N extension
* algorithm and start extending the slot table size by pt_maxdelta.
*
! * Device entries /dev/pts directory are created dynamically by the
! * /dev filesystem. We no longer call ddi_create_minor_node() on
! * behalf of the slave driver. The /dev filesystem creates /dev/pts
! * nodes based on the pt_ttys array.
*
- * Synchronization:
*
! * All global data synchronization between ptm/pts is done via global
! * ptms_lock mutex which is implicitly initialized by declaring it global.
*
* Individual fields of pt_ttys structure (except ptm_rdq, pts_rdq and
* pt_nullmsg) are protected by pt_ttys.pt_lock mutex.
*
* 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).
*
! * 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. Put and service procedures
* use PT_ENTER_READ/PT_EXIT_READ to prevent peer closes.
--- 19,84 ----
* CDDL HEADER END
*/
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
+ * Copyright 2021 Oxide Computer Company
*/
/*
! * PSEUDO-TERMINAL COMMON DATA AND ROUTINES (PTM, PTS)
*
! * This file contains global data and code shared between manager and
! * subsidiary parts of the pseudo-terminal driver.
*
! * Pseudo-terminals (or ptys for short) are allocated dynamically.
! * ptys are put in the global ptms_slots array indexed by minor numbers.
! *
! * The slots array is initially small (of the size NPTY_MIN). When more ptys are
* needed than the slot array size, the larger slot array is allocated and all
! * opened ptys move to the new one.
*
*
! * RESOURCE ALLOCATION
! *
! * - pt_ttys structures are allocated via pt_ttys_alloc, which uses
* kmem_cache_alloc().
! * - Minor number space is allocated via vmem_alloc() interface.
! * - ptms_slots arrays are allocated via kmem_alloc().
*
! * Minors start from 1 instead of 0, because vmem_alloc() returns 0 in case of
! * failure. Also, in anticipation of removing the clone device interface to
* pseudo-terminal subsystem, minor 0 should not be used. (Potential future
* development).
*
* After the table slot size reaches pt_maxdelta, we stop 2^N extension
* algorithm and start extending the slot table size by pt_maxdelta.
*
! * Device entries /dev/pts directory are created dynamically by the /dev
! * filesystem. We no longer call ddi_create_minor_node() on behalf of the
! * subsidiary driver. The /dev filesystem creates /dev/pts nodes based on the
! * pt_ttys array.
*
*
! * SYNCHRONIZATION
*
+ * All global data synchronization between ptm/pts is done via global ptms_lock
+ * mutex which is implicitly initialized by declaring it global.
+ *
* Individual fields of pt_ttys structure (except ptm_rdq, pts_rdq and
* pt_nullmsg) are protected by pt_ttys.pt_lock mutex.
*
* 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).
*
! * 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. Put and service procedures
* use PT_ENTER_READ/PT_EXIT_READ to prevent peer closes.
*** 80,96 ****
*
* The pt_nullmsg field is only used in open/close routines and is also
* protected by PT_ENTER_WRITE/PT_EXIT_WRITE brackets to avoid extra mutex
* holds.
*
- * 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.
*
- * Global functions:
*
* void ptms_init(void);
*
* Called by pts/ptm _init entry points. It performes one-time
* initialization needed for both pts and ptm. This initialization is done
* here and not in ptms_initspace because all these data structures are not
--- 85,103 ----
*
* The pt_nullmsg field is only used in open/close routines and is also
* protected by PT_ENTER_WRITE/PT_EXIT_WRITE brackets to avoid extra mutex
* holds.
*
*
+ * 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.
*
*
+ * GLOBAL FUNCTIONS
+ *
* void ptms_init(void);
*
* Called by pts/ptm _init entry points. It performes one-time
* initialization needed for both pts and ptm. This initialization is done
* here and not in ptms_initspace because all these data structures are not
*** 115,124 ****
--- 122,132 ----
* 0 if not allocated or not for this zone.
* 1 if an allocated pty in the current zone.
* Also returns owner of pty.
*
* int ptms_minor_exists(minor_t minor)
+ *
* Check if minor refers to an allocated pty (in any zone)
* Returns
* 0 if not an allocated pty
* 1 if an allocated pty
*
*** 129,140 ****
* void ptms_close(struct pt_ttys *pt, uint_t flags_to_clear);
*
* Clear flags_to_clear in pt and if no one owns it (PTMOPEN/PTSOPEN not
* set) free pt entry and corresponding slot.
*
- * Tuneables and configuration:
*
* pt_cnt: minimum number of pseudo-terminals in the system. The system
* should provide at least this number of ptys (provided sufficient
* memory is available). It is different from the older semantics
* of pt_cnt meaning maximum number of ptys.
* Set to 0 by default.
--- 137,149 ----
* void ptms_close(struct pt_ttys *pt, uint_t flags_to_clear);
*
* Clear flags_to_clear in pt and if no one owns it (PTMOPEN/PTSOPEN not
* set) free pt entry and corresponding slot.
*
*
+ * TUNEABLES AND CONFIGURATION
+ *
* pt_cnt: minimum number of pseudo-terminals in the system. The system
* should provide at least this number of ptys (provided sufficient
* memory is available). It is different from the older semantics
* of pt_cnt meaning maximum number of ptys.
* Set to 0 by default.
*** 144,155 ****
* impose stricter maximum). Zero value means no user-defined
* maximum. This is intended to be used as "denial-of-service"
* protection.
* Set to 0 by default.
*
! * Both pt_cnt and pt_max_pty may be modified during system lifetime
! * with their semantics preserved.
*
* pt_init_cnt: Initial size of ptms_slots array. Set to NPTY_INITIAL.
*
* pt_ptyofmem: Approximate percentage of system memory that may be
* occupied by pty data structures. Initially set to NPTY_PERCENT.
--- 153,164 ----
* impose stricter maximum). Zero value means no user-defined
* maximum. This is intended to be used as "denial-of-service"
* protection.
* Set to 0 by default.
*
! * Both pt_cnt and pt_max_pty may be modified during system
! * lifetime with their semantics preserved.
*
* pt_init_cnt: Initial size of ptms_slots array. Set to NPTY_INITIAL.
*
* pt_ptyofmem: Approximate percentage of system memory that may be
* occupied by pty data structures. Initially set to NPTY_PERCENT.
*** 208,218 ****
static struct pt_ttys **ptms_slots = NULL; /* Slots for actual pt structures */
static size_t ptms_nslots = 0; /* Size of slot array */
static size_t ptms_ptymax = 0; /* Maximum number of ptys */
static size_t ptms_inuse = 0; /* # of ptys currently allocated */
! dev_info_t *pts_dip = NULL; /* set if slave is attached */
static struct kmem_cache *ptms_cache = NULL; /* pty cache */
static vmem_t *ptms_minor_arena = NULL; /* Arena for device minors */
--- 217,227 ----
static struct pt_ttys **ptms_slots = NULL; /* Slots for actual pt structures */
static size_t ptms_nslots = 0; /* Size of slot array */
static size_t ptms_ptymax = 0; /* Maximum number of ptys */
static size_t ptms_inuse = 0; /* # of ptys currently allocated */
! dev_info_t *pts_dip = NULL; /* Set if subsidiary is attached */
static struct kmem_cache *ptms_cache = NULL; /* pty cache */
static vmem_t *ptms_minor_arena = NULL; /* Arena for device minors */
*** 220,232 ****
static int ptms_constructor(void *, void *, int);
static void ptms_destructor(void *, void *);
static minor_t ptms_grow(void);
/*
! * Total size occupied by one pty. Each pty master/slave pair consumes one
! * pointer for ptms_slots array, one pt_ttys structure and one empty message
! * preallocated for pts close.
*/
#define PTY_SIZE (sizeof (struct pt_ttys) + \
sizeof (struct pt_ttys *) + \
sizeof (dblk_t))
--- 229,241 ----
static int ptms_constructor(void *, void *, int);
static void ptms_destructor(void *, void *);
static minor_t ptms_grow(void);
/*
! * Total size occupied by one pty. Each pty manager/subsidiary pair consumes
! * one pointer for ptms_slots array, one pt_ttys structure, and one empty
! * message preallocated for pts close.
*/
#define PTY_SIZE (sizeof (struct pt_ttys) + \
sizeof (struct pt_ttys *) + \
sizeof (dblk_t))
*** 293,303 ****
/*
* This routine attaches the pts dip.
*/
int
! ptms_attach_slave(void)
{
if (pts_dip == NULL && i_ddi_attach_pseudo_node("pts") == NULL)
return (-1);
ASSERT(pts_dip);
--- 302,312 ----
/*
* This routine attaches the pts dip.
*/
int
! ptms_attach_subsidiary(void)
{
if (pts_dip == NULL && i_ddi_attach_pseudo_node("pts") == NULL)
return (-1);
ASSERT(pts_dip);
*** 307,317 ****
/*
* Called from /dev fs. Checks if dip is attached,
* and if it is, returns its major number.
*/
major_t
! ptms_slave_attached(void)
{
major_t maj = DDI_MAJOR_T_NONE;
mutex_enter(&ptms_lock);
if (pts_dip)
--- 316,326 ----
/*
* Called from /dev fs. Checks if dip is attached,
* and if it is, returns its major number.
*/
major_t
! ptms_subsidiary_attached(void)
{
major_t maj = DDI_MAJOR_T_NONE;
mutex_enter(&ptms_lock);
if (pts_dip)