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NetBSD/sys/kern/kern_proc.c

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/* $NetBSD: kern_proc.c,v 1.106 2007/03/04 06:03:05 christos Exp $ */
/*-
* Copyright (c) 1999, 2006, 2007 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
* NASA Ames Research Center, and by Andrew Doran.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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.
*/
/*
* Copyright (c) 1982, 1986, 1989, 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
*
* @(#)kern_proc.c 8.7 (Berkeley) 2/14/95
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.106 2007/03/04 06:03:05 christos Exp $");
#include "opt_kstack.h"
#include "opt_maxuprc.h"
#include "opt_multiprocessor.h"
#include "opt_lockdebug.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/buf.h>
#include <sys/acct.h>
#include <sys/wait.h>
#include <sys/file.h>
#include <ufs/ufs/quota.h>
#include <sys/uio.h>
#include <sys/malloc.h>
#include <sys/pool.h>
#include <sys/mbuf.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/signalvar.h>
#include <sys/ras.h>
#include <sys/filedesc.h>
#include "sys/syscall_stats.h"
#include <sys/kauth.h>
#include <sys/sleepq.h>
#include <uvm/uvm.h>
#include <uvm/uvm_extern.h>
/*
* Other process lists
*/
struct proclist allproc;
struct proclist zombproc; /* resources have been freed */
/*
* There are two locks on global process state.
*
* 1. proclist_lock is a reader/writer lock and is used when modifying or
* examining process state from a process context. It protects our internal
* tables, all of the process lists, and a number of members of struct lwp
* and struct proc.
* 2. proclist_mutex is used when allproc must be traversed from an
* interrupt context, or when we must signal processes from an interrupt
* context. The proclist_lock should always be used in preference.
*
* proclist_lock proclist_mutex structure
* --------------- --------------- -----------------
* x zombproc
* x x pid_table
* x proc::p_pptr
* x proc::p_sibling
* x proc::p_children
* x x allproc
* x x proc::p_pgrp
* x x proc::p_pglist
* x x proc::p_session
* x x proc::p_list
* x alllwp
* x lwp::l_list
*
* The lock order for processes and LWPs is approximately as following:
*
* kernel_mutex
* -> proclist_lock
* -> proclist_mutex
* -> proc::p_mutex
* -> proc::p_smutex
*/
krwlock_t proclist_lock;
kmutex_t proclist_mutex;
/*
* pid to proc lookup is done by indexing the pid_table array.
* Since pid numbers are only allocated when an empty slot
* has been found, there is no need to search any lists ever.
* (an orphaned pgrp will lock the slot, a session will lock
* the pgrp with the same number.)
* If the table is too small it is reallocated with twice the
* previous size and the entries 'unzipped' into the two halves.
* A linked list of free entries is passed through the pt_proc
* field of 'free' items - set odd to be an invalid ptr.
*/
struct pid_table {
struct proc *pt_proc;
struct pgrp *pt_pgrp;
};
#if 1 /* strongly typed cast - should be a noop */
static inline uint p2u(struct proc *p) { return (uint)(uintptr_t)p; }
#else
#define p2u(p) ((uint)p)
#endif
#define P_VALID(p) (!(p2u(p) & 1))
#define P_NEXT(p) (p2u(p) >> 1)
#define P_FREE(pid) ((struct proc *)(uintptr_t)((pid) << 1 | 1))
#define INITIAL_PID_TABLE_SIZE (1 << 5)
static struct pid_table *pid_table;
static uint pid_tbl_mask = INITIAL_PID_TABLE_SIZE - 1;
static uint pid_alloc_lim; /* max we allocate before growing table */
static uint pid_alloc_cnt; /* number of allocated pids */
/* links through free slots - never empty! */
static uint next_free_pt, last_free_pt;
static pid_t pid_max = PID_MAX; /* largest value we allocate */
/* Components of the first process -- never freed. */
struct session session0;
struct pgrp pgrp0;
struct proc proc0;
struct lwp lwp0 __aligned(MIN_LWP_ALIGNMENT);
kauth_cred_t cred0;
struct filedesc0 filedesc0;
struct cwdinfo cwdi0;
struct plimit limit0;
struct pstats pstat0;
struct vmspace vmspace0;
struct sigacts sigacts0;
struct turnstile turnstile0;
extern struct user *proc0paddr;
extern const struct emul emul_netbsd; /* defined in kern_exec.c */
int nofile = NOFILE;
int maxuprc = MAXUPRC;
int cmask = CMASK;
POOL_INIT(proc_pool, sizeof(struct proc), 0, 0, 0, "procpl",
&pool_allocator_nointr);
POOL_INIT(pgrp_pool, sizeof(struct pgrp), 0, 0, 0, "pgrppl",
&pool_allocator_nointr);
POOL_INIT(plimit_pool, sizeof(struct plimit), 0, 0, 0, "plimitpl",
&pool_allocator_nointr);
POOL_INIT(pstats_pool, sizeof(struct pstats), 0, 0, 0, "pstatspl",
&pool_allocator_nointr);
POOL_INIT(rusage_pool, sizeof(struct rusage), 0, 0, 0, "rusgepl",
&pool_allocator_nointr);
POOL_INIT(session_pool, sizeof(struct session), 0, 0, 0, "sessionpl",
&pool_allocator_nointr);
MALLOC_DEFINE(M_EMULDATA, "emuldata", "Per-process emulation data");
MALLOC_DEFINE(M_PROC, "proc", "Proc structures");
MALLOC_DEFINE(M_SUBPROC, "subproc", "Proc sub-structures");
/*
* The process list descriptors, used during pid allocation and
* by sysctl. No locking on this data structure is needed since
* it is completely static.
*/
const struct proclist_desc proclists[] = {
{ &allproc },
{ &zombproc },
{ NULL },
};
static void orphanpg(struct pgrp *);
static void pg_delete(pid_t);
static specificdata_domain_t proc_specificdata_domain;
/*
* Initialize global process hashing structures.
*/
void
procinit(void)
{
const struct proclist_desc *pd;
int i;
#define LINK_EMPTY ((PID_MAX + INITIAL_PID_TABLE_SIZE) & ~(INITIAL_PID_TABLE_SIZE - 1))
for (pd = proclists; pd->pd_list != NULL; pd++)
LIST_INIT(pd->pd_list);
/*
* XXX p_smutex can be IPL_VM except for audio drivers
* XXX proclist_lock must die
*/
rw_init(&proclist_lock);
mutex_init(&proclist_mutex, MUTEX_SPIN, IPL_SCHED);
pid_table = malloc(INITIAL_PID_TABLE_SIZE * sizeof *pid_table,
M_PROC, M_WAITOK);
/* Set free list running through table...
Preset 'use count' above PID_MAX so we allocate pid 1 next. */
for (i = 0; i <= pid_tbl_mask; i++) {
pid_table[i].pt_proc = P_FREE(LINK_EMPTY + i + 1);
pid_table[i].pt_pgrp = 0;
}
/* slot 0 is just grabbed */
next_free_pt = 1;
/* Need to fix last entry. */
last_free_pt = pid_tbl_mask;
pid_table[last_free_pt].pt_proc = P_FREE(LINK_EMPTY);
/* point at which we grow table - to avoid reusing pids too often */
pid_alloc_lim = pid_tbl_mask - 1;
#undef LINK_EMPTY
LIST_INIT(&alllwp);
uihashtbl =
hashinit(maxproc / 16, HASH_LIST, M_PROC, M_WAITOK, &uihash);
proc_specificdata_domain = specificdata_domain_create();
KASSERT(proc_specificdata_domain != NULL);
}
/*
* Initialize process 0.
*/
void
proc0_init(void)
{
struct proc *p;
struct pgrp *pg;
struct session *sess;
struct lwp *l;
u_int i;
rlim_t lim;
p = &proc0;
pg = &pgrp0;
sess = &session0;
l = &lwp0;
/* XXX p_smutex can be IPL_VM except for audio drivers */
mutex_init(&p->p_smutex, MUTEX_SPIN, IPL_SCHED);
mutex_init(&p->p_stmutex, MUTEX_SPIN, IPL_STATCLOCK);
mutex_init(&p->p_rasmutex, MUTEX_SPIN, IPL_NONE);
mutex_init(&p->p_mutex, MUTEX_DEFAULT, IPL_NONE);
cv_init(&p->p_refcv, "drainref");
cv_init(&p->p_waitcv, "wait");
cv_init(&p->p_lwpcv, "lwpwait");
LIST_INIT(&p->p_lwps);
LIST_INIT(&p->p_sigwaiters);
LIST_INSERT_HEAD(&p->p_lwps, l, l_sibling);
p->p_nlwps = 1;
p->p_nrlwps = 1;
p->p_refcnt = 1;
pid_table[0].pt_proc = p;
LIST_INSERT_HEAD(&allproc, p, p_list);
LIST_INSERT_HEAD(&alllwp, l, l_list);
p->p_pgrp = pg;
pid_table[0].pt_pgrp = pg;
LIST_INIT(&pg->pg_members);
LIST_INSERT_HEAD(&pg->pg_members, p, p_pglist);
pg->pg_session = sess;
sess->s_count = 1;
sess->s_sid = 0;
sess->s_leader = p;
/*
* Set P_NOCLDWAIT so that kernel threads are reparented to
* init(8) when they exit. init(8) can easily wait them out
* for us.
*/
p->p_flag = PK_SYSTEM | PK_NOCLDWAIT;
p->p_stat = SACTIVE;
p->p_nice = NZERO;
p->p_emul = &emul_netbsd;
#ifdef __HAVE_SYSCALL_INTERN
(*p->p_emul->e_syscall_intern)(p);
#endif
strncpy(p->p_comm, "swapper", MAXCOMLEN);
l->l_mutex = &sched_mutex;
l->l_flag = LW_INMEM | LW_SYSTEM;
l->l_stat = LSONPROC;
l->l_ts = &turnstile0;
l->l_syncobj = &sched_syncobj;
l->l_refcnt = 1;
l->l_cpu = curcpu();
l->l_priority = PRIBIO;
l->l_usrpri = PRIBIO;
l->l_inheritedprio = MAXPRI;
SLIST_INIT(&l->l_pi_lenders);
callout_init(&l->l_tsleep_ch);
cv_init(&l->l_sigcv, "sigwait");
/* Create credentials. */
cred0 = kauth_cred_alloc();
p->p_cred = cred0;
kauth_cred_hold(cred0);
l->l_cred = cred0;
/* Create the CWD info. */
p->p_cwdi = &cwdi0;
cwdi0.cwdi_cmask = cmask;
cwdi0.cwdi_refcnt = 1;
simple_lock_init(&cwdi0.cwdi_slock);
/* Create the limits structures. */
p->p_limit = &limit0;
simple_lock_init(&limit0.p_slock);
for (i = 0; i < sizeof(p->p_rlimit)/sizeof(p->p_rlimit[0]); i++)
limit0.pl_rlimit[i].rlim_cur =
limit0.pl_rlimit[i].rlim_max = RLIM_INFINITY;
limit0.pl_rlimit[RLIMIT_NOFILE].rlim_max = maxfiles;
limit0.pl_rlimit[RLIMIT_NOFILE].rlim_cur =
maxfiles < nofile ? maxfiles : nofile;
limit0.pl_rlimit[RLIMIT_NPROC].rlim_max = maxproc;
limit0.pl_rlimit[RLIMIT_NPROC].rlim_cur =
maxproc < maxuprc ? maxproc : maxuprc;
lim = ptoa(uvmexp.free);
limit0.pl_rlimit[RLIMIT_RSS].rlim_max = lim;
limit0.pl_rlimit[RLIMIT_MEMLOCK].rlim_max = lim;
limit0.pl_rlimit[RLIMIT_MEMLOCK].rlim_cur = lim / 3;
limit0.pl_corename = defcorename;
limit0.p_refcnt = 1;
/* Configure virtual memory system, set vm rlimits. */
uvm_init_limits(p);
/* Initialize file descriptor table for proc0. */
p->p_fd = &filedesc0.fd_fd;
fdinit1(&filedesc0);
/*
* Initialize proc0's vmspace, which uses the kernel pmap.
* All kernel processes (which never have user space mappings)
* share proc0's vmspace, and thus, the kernel pmap.
*/
uvmspace_init(&vmspace0, pmap_kernel(), round_page(VM_MIN_ADDRESS),
trunc_page(VM_MAX_ADDRESS));
p->p_vmspace = &vmspace0;
l->l_addr = proc0paddr; /* XXX */
p->p_stats = &pstat0;
/* Initialize signal state for proc0. */
p->p_sigacts = &sigacts0;
mutex_init(&p->p_sigacts->sa_mutex, MUTEX_SPIN, IPL_NONE);
siginit(p);
proc_initspecific(p);
lwp_initspecific(l);
SYSCALL_TIME_LWP_INIT(l);
}
/*
* Check that the specified process group is in the session of the
* specified process.
* Treats -ve ids as process ids.
* Used to validate TIOCSPGRP requests.
*/
int
pgid_in_session(struct proc *p, pid_t pg_id)
{
struct pgrp *pgrp;
struct session *session;
rw_enter(&proclist_lock, RW_READER);
if (pg_id < 0) {
struct proc *p1 = p_find(-pg_id, PFIND_LOCKED | PFIND_UNLOCK_FAIL);
if (p1 == NULL)
return EINVAL;
pgrp = p1->p_pgrp;
} else {
pgrp = pg_find(pg_id, PFIND_LOCKED | PFIND_UNLOCK_FAIL);
if (pgrp == NULL)
return EINVAL;
}
session = pgrp->pg_session;
rw_exit(&proclist_lock);
if (session != p->p_pgrp->pg_session)
return EPERM;
return 0;
}
/*
* Is p an inferior of q?
*
* Call with the proclist_lock held.
*/
int
inferior(struct proc *p, struct proc *q)
{
for (; p != q; p = p->p_pptr)
if (p->p_pid == 0)
return 0;
return 1;
}
/*
* Locate a process by number
*/
struct proc *
p_find(pid_t pid, uint flags)
{
struct proc *p;
char stat;
if (!(flags & PFIND_LOCKED))
rw_enter(&proclist_lock, RW_READER);
p = pid_table[pid & pid_tbl_mask].pt_proc;
/* Only allow live processes to be found by pid. */
/* XXXSMP p_stat */
if (P_VALID(p) && p->p_pid == pid && ((stat = p->p_stat) == SACTIVE ||
stat == SSTOP || ((flags & PFIND_ZOMBIE) &&
(stat == SZOMB || stat == SDEAD || stat == SDYING)))) {
if (flags & PFIND_UNLOCK_OK)
rw_exit(&proclist_lock);
return p;
}
if (flags & PFIND_UNLOCK_FAIL)
rw_exit(&proclist_lock);
return NULL;
}
/*
* Locate a process group by number
*/
struct pgrp *
pg_find(pid_t pgid, uint flags)
{
struct pgrp *pg;
if (!(flags & PFIND_LOCKED))
rw_enter(&proclist_lock, RW_READER);
pg = pid_table[pgid & pid_tbl_mask].pt_pgrp;
/*
* Can't look up a pgrp that only exists because the session
* hasn't died yet (traditional)
*/
if (pg == NULL || pg->pg_id != pgid || LIST_EMPTY(&pg->pg_members)) {
if (flags & PFIND_UNLOCK_FAIL)
rw_exit(&proclist_lock);
return NULL;
}
if (flags & PFIND_UNLOCK_OK)
rw_exit(&proclist_lock);
return pg;
}
static void
expand_pid_table(void)
{
uint pt_size = pid_tbl_mask + 1;
struct pid_table *n_pt, *new_pt;
struct proc *proc;
struct pgrp *pgrp;
int i;
pid_t pid;
new_pt = malloc(pt_size * 2 * sizeof *new_pt, M_PROC, M_WAITOK);
rw_enter(&proclist_lock, RW_WRITER);
if (pt_size != pid_tbl_mask + 1) {
/* Another process beat us to it... */
rw_exit(&proclist_lock);
FREE(new_pt, M_PROC);
return;
}
/*
* Copy entries from old table into new one.
* If 'pid' is 'odd' we need to place in the upper half,
* even pid's to the lower half.
* Free items stay in the low half so we don't have to
* fixup the reference to them.
* We stuff free items on the front of the freelist
* because we can't write to unmodified entries.
* Processing the table backwards maintains a semblance
* of issueing pid numbers that increase with time.
*/
i = pt_size - 1;
n_pt = new_pt + i;
for (; ; i--, n_pt--) {
proc = pid_table[i].pt_proc;
pgrp = pid_table[i].pt_pgrp;
if (!P_VALID(proc)) {
/* Up 'use count' so that link is valid */
pid = (P_NEXT(proc) + pt_size) & ~pt_size;
proc = P_FREE(pid);
if (pgrp)
pid = pgrp->pg_id;
} else
pid = proc->p_pid;
/* Save entry in appropriate half of table */
n_pt[pid & pt_size].pt_proc = proc;
n_pt[pid & pt_size].pt_pgrp = pgrp;
/* Put other piece on start of free list */
pid = (pid ^ pt_size) & ~pid_tbl_mask;
n_pt[pid & pt_size].pt_proc =
P_FREE((pid & ~pt_size) | next_free_pt);
n_pt[pid & pt_size].pt_pgrp = 0;
next_free_pt = i | (pid & pt_size);
if (i == 0)
break;
}
/* Switch tables */
mutex_enter(&proclist_mutex);
n_pt = pid_table;
pid_table = new_pt;
mutex_exit(&proclist_mutex);
pid_tbl_mask = pt_size * 2 - 1;
/*
* pid_max starts as PID_MAX (= 30000), once we have 16384
* allocated pids we need it to be larger!
*/
if (pid_tbl_mask > PID_MAX) {
pid_max = pid_tbl_mask * 2 + 1;
pid_alloc_lim |= pid_alloc_lim << 1;
} else
pid_alloc_lim <<= 1; /* doubles number of free slots... */
rw_exit(&proclist_lock);
FREE(n_pt, M_PROC);
}
struct proc *
proc_alloc(void)
{
struct proc *p;
int nxt;
pid_t pid;
struct pid_table *pt;
p = pool_get(&proc_pool, PR_WAITOK);
p->p_stat = SIDL; /* protect against others */
proc_initspecific(p);
/* allocate next free pid */
for (;;expand_pid_table()) {
if (__predict_false(pid_alloc_cnt >= pid_alloc_lim))
/* ensure pids cycle through 2000+ values */
continue;
rw_enter(&proclist_lock, RW_WRITER);
pt = &pid_table[next_free_pt];
#ifdef DIAGNOSTIC
if (__predict_false(P_VALID(pt->pt_proc) || pt->pt_pgrp))
panic("proc_alloc: slot busy");
#endif
nxt = P_NEXT(pt->pt_proc);
if (nxt & pid_tbl_mask)
break;
/* Table full - expand (NB last entry not used....) */
rw_exit(&proclist_lock);
}
/* pid is 'saved use count' + 'size' + entry */
pid = (nxt & ~pid_tbl_mask) + pid_tbl_mask + 1 + next_free_pt;
if ((uint)pid > (uint)pid_max)
pid &= pid_tbl_mask;
p->p_pid = pid;
next_free_pt = nxt & pid_tbl_mask;
/* Grab table slot */
mutex_enter(&proclist_mutex);
pt->pt_proc = p;
mutex_exit(&proclist_mutex);
pid_alloc_cnt++;
rw_exit(&proclist_lock);
return p;
}
/*
* Free last resources of a process - called from proc_free (in kern_exit.c)
*
* Called with the proclist_lock write held, and releases upon exit.
*/
void
proc_free_mem(struct proc *p)
{
pid_t pid = p->p_pid;
struct pid_table *pt;
LOCK_ASSERT(rw_write_held(&proclist_lock));
pt = &pid_table[pid & pid_tbl_mask];
#ifdef DIAGNOSTIC
if (__predict_false(pt->pt_proc != p))
panic("proc_free: pid_table mismatch, pid %x, proc %p",
pid, p);
#endif
mutex_enter(&proclist_mutex);
/* save pid use count in slot */
pt->pt_proc = P_FREE(pid & ~pid_tbl_mask);
if (pt->pt_pgrp == NULL) {
/* link last freed entry onto ours */
pid &= pid_tbl_mask;
pt = &pid_table[last_free_pt];
pt->pt_proc = P_FREE(P_NEXT(pt->pt_proc) | pid);
last_free_pt = pid;
pid_alloc_cnt--;
}
mutex_exit(&proclist_mutex);
nprocs--;
rw_exit(&proclist_lock);
pool_put(&proc_pool, p);
}
/*
* Move p to a new or existing process group (and session)
*
* If we are creating a new pgrp, the pgid should equal
* the calling process' pid.
* If is only valid to enter a process group that is in the session
* of the process.
* Also mksess should only be set if we are creating a process group
*
* Only called from sys_setsid, sys_setpgid/sys_setpgrp and the
* SYSV setpgrp support for hpux.
*/
int
enterpgrp(struct proc *curp, pid_t pid, pid_t pgid, int mksess)
{
struct pgrp *new_pgrp, *pgrp;
struct session *sess;
struct proc *p;
int rval;
pid_t pg_id = NO_PGID;
/* Allocate data areas we might need before doing any validity checks */
rw_enter(&proclist_lock, RW_READER); /* Because pid_table might change */
if (pid_table[pgid & pid_tbl_mask].pt_pgrp == 0) {
rw_exit(&proclist_lock);
new_pgrp = pool_get(&pgrp_pool, PR_WAITOK);
} else {
rw_exit(&proclist_lock);
new_pgrp = NULL;
}
if (mksess)
sess = pool_get(&session_pool, PR_WAITOK);
else
sess = NULL;
rw_enter(&proclist_lock, RW_WRITER);
rval = EPERM; /* most common error (to save typing) */
/* Check pgrp exists or can be created */
pgrp = pid_table[pgid & pid_tbl_mask].pt_pgrp;
if (pgrp != NULL && pgrp->pg_id != pgid)
goto done;
/* Can only set another process under restricted circumstances. */
if (pid != curp->p_pid) {
/* must exist and be one of our children... */
if ((p = p_find(pid, PFIND_LOCKED)) == NULL ||
!inferior(p, curp)) {
rval = ESRCH;
goto done;
}
/* ... in the same session... */
if (sess != NULL || p->p_session != curp->p_session)
goto done;
/* ... existing pgid must be in same session ... */
if (pgrp != NULL && pgrp->pg_session != p->p_session)
goto done;
/* ... and not done an exec. */
if (p->p_flag & PK_EXEC) {
rval = EACCES;
goto done;
}
} else {
/* ... setsid() cannot re-enter a pgrp */
if (mksess && (curp->p_pgid == curp->p_pid ||
pg_find(curp->p_pid, PFIND_LOCKED)))
goto done;
p = curp;
}
/* Changing the process group/session of a session
leader is definitely off limits. */
if (SESS_LEADER(p)) {
if (sess == NULL && p->p_pgrp == pgrp)
/* unless it's a definite noop */
rval = 0;
goto done;
}
/* Can only create a process group with id of process */
if (pgrp == NULL && pgid != pid)
goto done;
/* Can only create a session if creating pgrp */
if (sess != NULL && pgrp != NULL)
goto done;
/* Check we allocated memory for a pgrp... */
if (pgrp == NULL && new_pgrp == NULL)
goto done;
/* Don't attach to 'zombie' pgrp */
if (pgrp != NULL && LIST_EMPTY(&pgrp->pg_members))
goto done;
/* Expect to succeed now */
rval = 0;
if (pgrp == p->p_pgrp)
/* nothing to do */
goto done;
/* Ok all setup, link up required structures */
if (pgrp == NULL) {
pgrp = new_pgrp;
new_pgrp = 0;
if (sess != NULL) {
sess->s_sid = p->p_pid;
sess->s_leader = p;
sess->s_count = 1;
sess->s_ttyvp = NULL;
sess->s_ttyp = NULL;
sess->s_flags = p->p_session->s_flags & ~S_LOGIN_SET;
memcpy(sess->s_login, p->p_session->s_login,
sizeof(sess->s_login));
p->p_lflag &= ~PL_CONTROLT;
} else {
sess = p->p_pgrp->pg_session;
SESSHOLD(sess);
}
pgrp->pg_session = sess;
sess = 0;
pgrp->pg_id = pgid;
LIST_INIT(&pgrp->pg_members);
#ifdef DIAGNOSTIC
if (__predict_false(pid_table[pgid & pid_tbl_mask].pt_pgrp))
panic("enterpgrp: pgrp table slot in use");
if (__predict_false(mksess && p != curp))
panic("enterpgrp: mksession and p != curproc");
#endif
mutex_enter(&proclist_mutex);
pid_table[pgid & pid_tbl_mask].pt_pgrp = pgrp;
pgrp->pg_jobc = 0;
} else
mutex_enter(&proclist_mutex);
#ifdef notyet
/*
* If there's a controlling terminal for the current session, we
* have to interlock with it. See ttread().
*/
if (p->p_session->s_ttyvp != NULL) {
tp = p->p_session->s_ttyp;
mutex_enter(&tp->t_mutex);
} else
tp = NULL;
#endif
/*
* Adjust eligibility of affected pgrps to participate in job control.
* Increment eligibility counts before decrementing, otherwise we
* could reach 0 spuriously during the first call.
*/
fixjobc(p, pgrp, 1);
fixjobc(p, p->p_pgrp, 0);
/* Move process to requested group. */
LIST_REMOVE(p, p_pglist);
if (LIST_EMPTY(&p->p_pgrp->pg_members))
/* defer delete until we've dumped the lock */
pg_id = p->p_pgrp->pg_id;
p->p_pgrp = pgrp;
LIST_INSERT_HEAD(&pgrp->pg_members, p, p_pglist);
mutex_exit(&proclist_mutex);
#ifdef notyet
/* Done with the swap; we can release the tty mutex. */
if (tp != NULL)
mutex_exit(&tp->t_mutex);
#endif
done:
if (pg_id != NO_PGID)
pg_delete(pg_id);
rw_exit(&proclist_lock);
if (sess != NULL)
pool_put(&session_pool, sess);
if (new_pgrp != NULL)
pool_put(&pgrp_pool, new_pgrp);
#ifdef DEBUG_PGRP
if (__predict_false(rval))
printf("enterpgrp(%d,%d,%d), curproc %d, rval %d\n",
pid, pgid, mksess, curp->p_pid, rval);
#endif
return rval;
}
/*
* Remove a process from its process group. Must be called with the
* proclist_lock write held.
*/
void
leavepgrp(struct proc *p)
{
struct pgrp *pgrp;
LOCK_ASSERT(rw_write_held(&proclist_lock));
/*
* If there's a controlling terminal for the session, we have to
* interlock with it. See ttread().
*/
mutex_enter(&proclist_mutex);
#ifdef notyet
if (p_>p_session->s_ttyvp != NULL) {
tp = p->p_session->s_ttyp;
mutex_enter(&tp->t_mutex);
} else
tp = NULL;
#endif
pgrp = p->p_pgrp;
LIST_REMOVE(p, p_pglist);
p->p_pgrp = NULL;
#ifdef notyet
if (tp != NULL)
mutex_exit(&tp->t_mutex);
#endif
mutex_exit(&proclist_mutex);
if (LIST_EMPTY(&pgrp->pg_members))
pg_delete(pgrp->pg_id);
}
/*
* Free a process group. Must be called with the proclist_lock write held.
*/
static void
pg_free(pid_t pg_id)
{
struct pgrp *pgrp;
struct pid_table *pt;
LOCK_ASSERT(rw_write_held(&proclist_lock));
pt = &pid_table[pg_id & pid_tbl_mask];
pgrp = pt->pt_pgrp;
#ifdef DIAGNOSTIC
if (__predict_false(!pgrp || pgrp->pg_id != pg_id
|| !LIST_EMPTY(&pgrp->pg_members)))
panic("pg_free: process group absent or has members");
#endif
pt->pt_pgrp = 0;
if (!P_VALID(pt->pt_proc)) {
/* orphaned pgrp, put slot onto free list */
#ifdef DIAGNOSTIC
if (__predict_false(P_NEXT(pt->pt_proc) & pid_tbl_mask))
panic("pg_free: process slot on free list");
#endif
mutex_enter(&proclist_mutex);
pg_id &= pid_tbl_mask;
pt = &pid_table[last_free_pt];
pt->pt_proc = P_FREE(P_NEXT(pt->pt_proc) | pg_id);
mutex_exit(&proclist_mutex);
last_free_pt = pg_id;
pid_alloc_cnt--;
}
pool_put(&pgrp_pool, pgrp);
}
/*
* Delete a process group. Must be called with the proclist_lock write
* held.
*/
static void
pg_delete(pid_t pg_id)
{
struct pgrp *pgrp;
struct tty *ttyp;
struct session *ss;
int is_pgrp_leader;
LOCK_ASSERT(rw_write_held(&proclist_lock));
pgrp = pid_table[pg_id & pid_tbl_mask].pt_pgrp;
if (pgrp == NULL || pgrp->pg_id != pg_id ||
!LIST_EMPTY(&pgrp->pg_members))
return;
ss = pgrp->pg_session;
/* Remove reference (if any) from tty to this process group */
ttyp = ss->s_ttyp;
if (ttyp != NULL && ttyp->t_pgrp == pgrp) {
ttyp->t_pgrp = NULL;
#ifdef DIAGNOSTIC
if (ttyp->t_session != ss)
panic("pg_delete: wrong session on terminal");
#endif
}
/*
* The leading process group in a session is freed
* by sessdelete() if last reference.
*/
is_pgrp_leader = (ss->s_sid == pgrp->pg_id);
SESSRELE(ss);
if (is_pgrp_leader)
return;
pg_free(pg_id);
}
/*
* Delete session - called from SESSRELE when s_count becomes zero.
* Must be called with the proclist_lock write held.
*/
void
sessdelete(struct session *ss)
{
LOCK_ASSERT(rw_write_held(&proclist_lock));
/*
* We keep the pgrp with the same id as the session in
* order to stop a process being given the same pid.
* Since the pgrp holds a reference to the session, it
* must be a 'zombie' pgrp by now.
*/
pg_free(ss->s_sid);
pool_put(&session_pool, ss);
}
/*
* Adjust pgrp jobc counters when specified process changes process group.
* We count the number of processes in each process group that "qualify"
* the group for terminal job control (those with a parent in a different
* process group of the same session). If that count reaches zero, the
* process group becomes orphaned. Check both the specified process'
* process group and that of its children.
* entering == 0 => p is leaving specified group.
* entering == 1 => p is entering specified group.
*
* Call with proclist_lock write held.
*/
void
fixjobc(struct proc *p, struct pgrp *pgrp, int entering)
{
struct pgrp *hispgrp;
struct session *mysession = pgrp->pg_session;
struct proc *child;
LOCK_ASSERT(rw_write_held(&proclist_lock));
LOCK_ASSERT(mutex_owned(&proclist_mutex));
/*
* Check p's parent to see whether p qualifies its own process
* group; if so, adjust count for p's process group.
*/
hispgrp = p->p_pptr->p_pgrp;
if (hispgrp != pgrp && hispgrp->pg_session == mysession) {
if (entering) {
mutex_enter(&p->p_smutex);
p->p_sflag &= ~PS_ORPHANPG;
mutex_exit(&p->p_smutex);
pgrp->pg_jobc++;
} else if (--pgrp->pg_jobc == 0)
orphanpg(pgrp);
}
/*
* Check this process' children to see whether they qualify
* their process groups; if so, adjust counts for children's
* process groups.
*/
LIST_FOREACH(child, &p->p_children, p_sibling) {
hispgrp = child->p_pgrp;
if (hispgrp != pgrp && hispgrp->pg_session == mysession &&
!P_ZOMBIE(child)) {
if (entering) {
mutex_enter(&child->p_smutex);
child->p_sflag &= ~PS_ORPHANPG;
mutex_exit(&child->p_smutex);
hispgrp->pg_jobc++;
} else if (--hispgrp->pg_jobc == 0)
orphanpg(hispgrp);
}
}
}
/*
* A process group has become orphaned;
* if there are any stopped processes in the group,
* hang-up all process in that group.
*
* Call with proclist_lock write held.
*/
static void
orphanpg(struct pgrp *pg)
{
struct proc *p;
int doit;
LOCK_ASSERT(rw_write_held(&proclist_lock));
LOCK_ASSERT(mutex_owned(&proclist_mutex));
doit = 0;
LIST_FOREACH(p, &pg->pg_members, p_pglist) {
mutex_enter(&p->p_smutex);
if (p->p_stat == SSTOP) {
doit = 1;
p->p_sflag |= PS_ORPHANPG;
}
mutex_exit(&p->p_smutex);
}
if (doit) {
LIST_FOREACH(p, &pg->pg_members, p_pglist) {
psignal(p, SIGHUP);
psignal(p, SIGCONT);
}
}
}
#ifdef DDB
#include <ddb/db_output.h>
void pidtbl_dump(void);
void
pidtbl_dump(void)
{
struct pid_table *pt;
struct proc *p;
struct pgrp *pgrp;
int id;
db_printf("pid table %p size %x, next %x, last %x\n",
pid_table, pid_tbl_mask+1,
next_free_pt, last_free_pt);
for (pt = pid_table, id = 0; id <= pid_tbl_mask; id++, pt++) {
p = pt->pt_proc;
if (!P_VALID(p) && !pt->pt_pgrp)
continue;
db_printf(" id %x: ", id);
if (P_VALID(p))
db_printf("proc %p id %d (0x%x) %s\n",
p, p->p_pid, p->p_pid, p->p_comm);
else
db_printf("next %x use %x\n",
P_NEXT(p) & pid_tbl_mask,
P_NEXT(p) & ~pid_tbl_mask);
if ((pgrp = pt->pt_pgrp)) {
db_printf("\tsession %p, sid %d, count %d, login %s\n",
pgrp->pg_session, pgrp->pg_session->s_sid,
pgrp->pg_session->s_count,
pgrp->pg_session->s_login);
db_printf("\tpgrp %p, pg_id %d, pg_jobc %d, members %p\n",
pgrp, pgrp->pg_id, pgrp->pg_jobc,
pgrp->pg_members.lh_first);
for (p = pgrp->pg_members.lh_first; p != 0;
p = p->p_pglist.le_next) {
db_printf("\t\tpid %d addr %p pgrp %p %s\n",
p->p_pid, p, p->p_pgrp, p->p_comm);
}
}
}
}
#endif /* DDB */
#ifdef KSTACK_CHECK_MAGIC
#include <sys/user.h>
#define KSTACK_MAGIC 0xdeadbeaf
/* XXX should be per process basis? */
int kstackleftmin = KSTACK_SIZE;
int kstackleftthres = KSTACK_SIZE / 8; /* warn if remaining stack is
less than this */
void
kstack_setup_magic(const struct lwp *l)
{
uint32_t *ip;
uint32_t const *end;
KASSERT(l != NULL);
KASSERT(l != &lwp0);
/*
* fill all the stack with magic number
* so that later modification on it can be detected.
*/
ip = (uint32_t *)KSTACK_LOWEST_ADDR(l);
end = (uint32_t *)((void *)KSTACK_LOWEST_ADDR(l) + KSTACK_SIZE);
for (; ip < end; ip++) {
*ip = KSTACK_MAGIC;
}
}
void
kstack_check_magic(const struct lwp *l)
{
uint32_t const *ip, *end;
int stackleft;
KASSERT(l != NULL);
/* don't check proc0 */ /*XXX*/
if (l == &lwp0)
return;
#ifdef __MACHINE_STACK_GROWS_UP
/* stack grows upwards (eg. hppa) */
ip = (uint32_t *)((void *)KSTACK_LOWEST_ADDR(l) + KSTACK_SIZE);
end = (uint32_t *)KSTACK_LOWEST_ADDR(l);
for (ip--; ip >= end; ip--)
if (*ip != KSTACK_MAGIC)
break;
stackleft = (void *)KSTACK_LOWEST_ADDR(l) + KSTACK_SIZE - (void *)ip;
#else /* __MACHINE_STACK_GROWS_UP */
/* stack grows downwards (eg. i386) */
ip = (uint32_t *)KSTACK_LOWEST_ADDR(l);
end = (uint32_t *)((void *)KSTACK_LOWEST_ADDR(l) + KSTACK_SIZE);
for (; ip < end; ip++)
if (*ip != KSTACK_MAGIC)
break;
stackleft = ((const char *)ip) - (const char *)KSTACK_LOWEST_ADDR(l);
#endif /* __MACHINE_STACK_GROWS_UP */
if (kstackleftmin > stackleft) {
kstackleftmin = stackleft;
if (stackleft < kstackleftthres)
printf("warning: kernel stack left %d bytes"
"(pid %u:lid %u)\n", stackleft,
(u_int)l->l_proc->p_pid, (u_int)l->l_lid);
}
if (stackleft <= 0) {
panic("magic on the top of kernel stack changed for "
"pid %u, lid %u: maybe kernel stack overflow",
(u_int)l->l_proc->p_pid, (u_int)l->l_lid);
}
}
#endif /* KSTACK_CHECK_MAGIC */
/*
* XXXSMP this is bust, it grabs a read lock and then messes about
* with allproc.
*/
int
proclist_foreach_call(struct proclist *list,
int (*callback)(struct proc *, void *arg), void *arg)
{
struct proc marker;
struct proc *p;
struct lwp * const l = curlwp;
int ret = 0;
marker.p_flag = PK_MARKER;
PHOLD(l);
rw_enter(&proclist_lock, RW_READER);
for (p = LIST_FIRST(list); ret == 0 && p != NULL;) {
if (p->p_flag & PK_MARKER) {
p = LIST_NEXT(p, p_list);
continue;
}
LIST_INSERT_AFTER(p, &marker, p_list);
ret = (*callback)(p, arg);
KASSERT(rw_read_held(&proclist_lock));
p = LIST_NEXT(&marker, p_list);
LIST_REMOVE(&marker, p_list);
}
rw_exit(&proclist_lock);
PRELE(l);
return ret;
}
int
proc_vmspace_getref(struct proc *p, struct vmspace **vm)
{
/* XXXCDC: how should locking work here? */
/* curproc exception is for coredump. */
if ((p != curproc && (p->p_sflag & PS_WEXIT) != 0) ||
(p->p_vmspace->vm_refcnt < 1)) { /* XXX */
return EFAULT;
}
uvmspace_addref(p->p_vmspace);
*vm = p->p_vmspace;
return 0;
}
/*
* Acquire a write lock on the process credential.
*/
void
proc_crmod_enter(void)
{
struct lwp *l = curlwp;
struct proc *p = l->l_proc;
struct plimit *lim;
kauth_cred_t oc;
char *cn;
mutex_enter(&p->p_mutex);
/* Ensure the LWP cached credentials are up to date. */
if ((oc = l->l_cred) != p->p_cred) {
kauth_cred_hold(p->p_cred);
l->l_cred = p->p_cred;
kauth_cred_free(oc);
}
/* Reset what needs to be reset in plimit. */
lim = p->p_limit;
if (lim->pl_corename != defcorename) {
if (lim->p_refcnt > 1 &&
(lim->p_lflags & PL_SHAREMOD) == 0) {
p->p_limit = limcopy(p);
limfree(lim);
lim = p->p_limit;
}
simple_lock(&lim->p_slock);
cn = lim->pl_corename;
lim->pl_corename = defcorename;
simple_unlock(&lim->p_slock);
if (cn != defcorename)
free(cn, M_TEMP);
}
}
/*
* Set in a new process credential, and drop the write lock. The credential
* must have a reference already. Optionally, free a no-longer required
* credential. The scheduler also needs to inspect p_cred, so we also
* briefly acquire the sched state mutex.
*/
void
proc_crmod_leave(kauth_cred_t scred, kauth_cred_t fcred, bool sugid)
{
struct lwp *l = curlwp;
struct proc *p = l->l_proc;
kauth_cred_t oc;
/* Is there a new credential to set in? */
if (scred != NULL) {
mutex_enter(&p->p_smutex);
p->p_cred = scred;
mutex_exit(&p->p_smutex);
/* Ensure the LWP cached credentials are up to date. */
if ((oc = l->l_cred) != scred) {
kauth_cred_hold(scred);
l->l_cred = scred;
}
} else
oc = NULL; /* XXXgcc */
if (sugid) {
/*
* Mark process as having changed credentials, stops
* tracing etc.
*/
p->p_flag |= PK_SUGID;
}
mutex_exit(&p->p_mutex);
/* If there is a credential to be released, free it now. */
if (fcred != NULL) {
KASSERT(scred != NULL);
kauth_cred_free(fcred);
if (oc != scred)
kauth_cred_free(oc);
}
}
/*
* Acquire a reference on a process, to prevent it from exiting or execing.
*/
int
proc_addref(struct proc *p)
{
LOCK_ASSERT(mutex_owned(&p->p_mutex));
if (p->p_refcnt <= 0)
return EAGAIN;
p->p_refcnt++;
return 0;
}
/*
* Release a reference on a process.
*/
void
proc_delref(struct proc *p)
{
LOCK_ASSERT(mutex_owned(&p->p_mutex));
if (p->p_refcnt < 0) {
if (++p->p_refcnt == 0)
cv_broadcast(&p->p_refcv);
} else {
p->p_refcnt--;
KASSERT(p->p_refcnt != 0);
}
}
/*
* Wait for all references on the process to drain, and prevent new
* references from being acquired.
*/
void
proc_drainrefs(struct proc *p)
{
LOCK_ASSERT(mutex_owned(&p->p_mutex));
KASSERT(p->p_refcnt > 0);
/*
* The process itself holds the last reference. Once it's released,
* no new references will be granted. If we have already locked out
* new references (refcnt <= 0), potentially due to a failed exec,
* there is nothing more to do.
*/
p->p_refcnt = 1 - p->p_refcnt;
while (p->p_refcnt != 0)
cv_wait(&p->p_refcv, &p->p_mutex);
}
/*
* proc_specific_key_create --
* Create a key for subsystem proc-specific data.
*/
int
proc_specific_key_create(specificdata_key_t *keyp, specificdata_dtor_t dtor)
{
return (specificdata_key_create(proc_specificdata_domain, keyp, dtor));
}
/*
* proc_specific_key_delete --
* Delete a key for subsystem proc-specific data.
*/
void
proc_specific_key_delete(specificdata_key_t key)
{
specificdata_key_delete(proc_specificdata_domain, key);
}
/*
* proc_initspecific --
* Initialize a proc's specificdata container.
*/
void
proc_initspecific(struct proc *p)
{
int error;
error = specificdata_init(proc_specificdata_domain, &p->p_specdataref);
KASSERT(error == 0);
}
/*
* proc_finispecific --
* Finalize a proc's specificdata container.
*/
void
proc_finispecific(struct proc *p)
{
specificdata_fini(proc_specificdata_domain, &p->p_specdataref);
}
/*
* proc_getspecific --
* Return proc-specific data corresponding to the specified key.
*/
void *
proc_getspecific(struct proc *p, specificdata_key_t key)
{
return (specificdata_getspecific(proc_specificdata_domain,
&p->p_specdataref, key));
}
/*
* proc_setspecific --
* Set proc-specific data corresponding to the specified key.
*/
void
proc_setspecific(struct proc *p, specificdata_key_t key, void *data)
{
specificdata_setspecific(proc_specificdata_domain,
&p->p_specdataref, key, data);
}
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