lwp.c revision aab2fe4104e428e5213f84aee65b9905ec97cf9a
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2009 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#include <sys/sysmacros.h>
#include <sys/schedctl.h>
#include <sys/lwp_upimutex_impl.h>
#include <sys/contract_impl.h>
#include <sys/cpc_impl.h>
/* hash function for the lwpid hash table, p->p_tidhash[] */
void *segkp_lwp; /* cookie for pool of segkp resources */
extern void reapq_move_lq_to_tq(kthread_t *);
extern void freectx_ctx(struct ctxop *);
/*
* Create a kernel thread associated with a particular system process. Give
* it an LWP so that microstate accounting will be available for it.
*/
{
}
/*
* Create a thread that appears to be stopped at sys_rtt.
*/
klwp_t *
{
kthread_t *t;
int err = 0;
uint_t old_hashsz = 0;
int i;
int rctlfail = 0;
mutex_enter(&p->p_lock);
/*
* don't enforce rctl limits on system processes
*/
if (!CLASS_KERNEL(cid)) {
1, 0) & RCT_DENY)
rctlfail = 1;
& RCT_DENY)
rctlfail = 1;
1, 0) & RCT_DENY)
rctlfail = 1;
}
if (rctlfail) {
mutex_exit(&p->p_lock);
return (NULL);
}
p->p_zone->zone_nlwps++;
mutex_exit(&p->p_lock);
if (CLASS_KERNEL(cid)) {
/*
* Since we are creating an LWP in an SSYS process, we do not
* inherit anything from the current thread's LWP. We set
* stksize and lwpdata to 0 in order to let thread_create()
* allocate a regular kernel thread stack for this thread.
*/
stksize = 0;
} else if (stksize == lwp_default_stksize) {
/*
* Try to reuse an <lwp,stack> from the LWP deathrow.
*/
if (lwp_reapcnt > 0) {
if ((t = lwp_deathrow) != NULL) {
lwp_deathrow = t->t_forw;
lwp_reapcnt--;
}
}
}
}
mutex_enter(&p->p_lock);
p->p_zone->zone_nlwps--;
mutex_exit(&p->p_lock);
return (NULL);
}
} else {
mutex_enter(&p->p_lock);
p->p_zone->zone_nlwps--;
mutex_exit(&p->p_lock);
return (NULL);
}
}
/*
* Create a thread, initializing the stack pointer
*/
/*
* If a non-NULL stack base is passed in, thread_create() assumes
* that the stack might be statically allocated (as opposed to being
* allocated from segkp), and so it does not set t_swap. Since
* the lwpdata was allocated from segkp, we must set t_swap to point
* to it ourselves.
*
* This would be less confusing if t_swap had a better name; it really
* indicates that the stack is allocated from segkp, regardless of
* whether or not it is swappable.
*/
}
/*
* If the stack and lwp can be reused, mark the thread as such.
* When we get to reapq_add() from resume_from_zombie(), these
* threads will go onto lwp_deathrow instead of thread_deathrow.
*/
t->t_flag |= T_LWPREUSE;
lwp->lwp_thread = t;
/*
* Allocate the SIGPROF buffer if ITIMER_REALPROF is in effect.
*/
if (p->p_rprof_cyclic != CYCLIC_NONE)
/*
* Allocate an lwp directory entry for the new lwp.
*/
mutex_enter(&p->p_lock);
grow:
/*
* Grow the lwp (thread) directory and lwpid hash table if necessary.
* A note on the growth algorithm:
* The new lwp directory size is computed as:
* new = 2 * old + 2
* Starting with an initial size of 2 (see exec_common()),
* this yields numbers that are a power of two minus 2:
* 2, 6, 14, 30, 62, 126, 254, 510, 1022, ...
* The size of the lwpid hash table must be a power of two
* and must be commensurate in size with the lwp directory
* so that hash bucket chains remain short. Therefore,
* the lwpid hash table size is computed as:
* hashsz = (dirsz + 2) / 2
* which leads to these hash table sizes corresponding to
* the above directory sizes:
* 2, 4, 8, 16, 32, 64, 128, 256, 512, ...
* A note on growing the hash table:
* For performance reasons, code in lwp_unpark() does not
* acquire curproc->p_lock when searching the hash table.
* Rather, it calls lwp_hash_lookup_and_lock() which
* acquires only the individual hash bucket lock, taking
* care to deal with reallocation of the hash table
* during the time it takes to acquire the lock.
*
* This is sufficient to protect the integrity of the
* hash table, but it requires us to acquire all of the
* old hash bucket locks before growing the hash table
* and to release them afterwards. It also requires us
* not to free the old hash table because some thread
* in lwp_hash_lookup_and_lock() might still be trying
* to acquire the old bucket lock.
*
* So we adopt the tactic of keeping all of the retired
* hash tables on a linked list, so they can be safely
* freed when the process exits or execs.
*
* Because the hash table grows in powers of two, the
* total size of all of the hash tables will be slightly
* less than twice the size of the largest hash table.
*/
mutex_exit(&p->p_lock);
/*
* Prepare to remember the old p_tidhash for later
* kmem_free()ing when the process exits or execs.
*/
if (ret_tidhash == NULL)
KM_SLEEP);
KM_SLEEP);
mutex_enter(&p->p_lock);
if (p == curproc)
prbarrier(p);
/*
* Someone else beat us to it or some lwp exited.
* Set up to free our memory and take a lap.
*/
} else {
/*
* For the benefit of lwp_hash_lookup_and_lock(),
* called from lwp_unpark(), which searches the
* tid hash table without acquiring p->p_lock,
* we must acquire all of the tid hash table
* locks before replacing p->p_tidhash.
*/
old_hashsz = p->p_tidhash_sz;
for (i = 0; i < old_hashsz; i++) {
}
/*
* We simply hash in all of the old directory entries.
* This works because the old directory has no empty
* slots and the new hash table starts out empty.
* This reproduces the original directory ordering
* (required for /proc directory semantics).
*/
old_dirsz = p->p_lwpdir_sz;
p->p_lwpdir_sz = new_dirsz;
new_hash, new_hashsz, 0);
/*
* Remember the old hash table along with all
* of the previously-remembered hash tables.
* We will free them at process exit or exec.
*/
p->p_ret_tidhash = ret_tidhash;
/*
* Now establish the new tid hash table.
* As soon as we assign p->p_tidhash,
* code in lwp_unpark() can start using it.
*/
/*
* It is necessary that p_tidhash reach global
* visibility before p_tidhash_sz. Otherwise,
* code in lwp_hash_lookup_and_lock() could
* index into the old p_tidhash using the new
* p_tidhash_sz and thereby access invalid data.
*/
p->p_tidhash_sz = new_hashsz;
/*
* Release the locks; allow lwp_unpark() to carry on.
*/
for (i = 0; i < old_hashsz; i++) {
}
/*
* Avoid freeing these objects below.
*/
ret_tidhash = NULL;
old_hashsz = 0;
}
}
/*
* Block the process against /proc while we manipulate p->p_tlist,
* unless lwp_create() was called by /proc for the PCAGENT operation.
* We want to do this early enough so that we don't drop p->p_lock
* until the thread is put on the p->p_tlist.
*/
if (p == curproc) {
prbarrier(p);
/*
* If the current lwp has been requested to stop, do so now.
* Otherwise we have a race condition between /proc attempting
* to stop the process and this thread creating a new lwp
* that was not seen when the /proc PCSTOP request was issued.
* We rely on stop() to call prbarrier(p) before returning.
*/
/*
* We called pool_barrier_enter() before calling
* here to lwp_create(). We have to call
* pool_barrier_exit() before stopping.
*/
prbarrier(p);
stop(PR_REQUESTED, 0);
/*
* And we have to repeat the call to
* pool_barrier_enter after stopping.
*/
prbarrier(p);
}
/*
* If process is exiting, there could be a race between
* the agent lwp creation and the new lwp currently being
* created. So to prevent this race lwp creation is failed
* if the process is exiting.
*/
err = 1;
goto error;
}
/*
* Since we might have dropped p->p_lock, the
* lwp directory free list might have changed.
*/
goto grow;
}
kpreempt_disable(); /* can't grab cpu_lock here */
/*
* Inherit processor and processor set bindings from curthread.
*
* For kernel LWPs, we do not inherit processor set bindings at
* process creation time (i.e. when p != curproc). After the
* kernel process is created, any subsequent LWPs must be created
* by threads in the kernel process, at which point we *will*
* inherit processor set bindings.
*/
t->t_bind_pset = PS_NONE;
} else {
t->t_bind_cpu = binding;
}
/*
* thread_create() initializes this thread's home lgroup to the root.
* Choose a more suitable lgroup, since this thread is associated
* with an lwp.
*/
} else if (CLASS_KERNEL(cid)) {
/*
* Kernel threads are always in the root lgrp.
*/
} else {
}
/*
* make sure lpl points to our own partition
*/
t->t_cpupart->cp_nlgrploads);
/*
* It is safe to point the thread to the new project without holding it
* since we're holding the target process' p_lock here and therefore
* we're guaranteed that it will not move to another project.
*/
(void) project_hold(newkpj);
}
/*
* If the lwp is being created in the current process
* and matches the current thread's scheduling class,
* we should propagate the current thread's scheduling
* parameters by calling CL_FORK. Otherwise just use
* the defaults by calling CL_ENTERCLASS.
*/
/*
* We don't call schedctl_set_cidpri(t) here
* because the schedctl data is not yet set
* up for the newly-created lwp.
*/
} else {
}
if (err)
goto error;
else
}
/*
* If we were given an lwpid then use it, else allocate one.
*/
if (lwpid != 0)
else {
/*
* Start again at 2 when INT_MAX has been reached
* (id_t is a signed 32-bit integer).
*/
do { /* avoid lwpid duplication */
p->p_lwpid = 1;
}
/*
* All lwpids are allocated; fail the request.
*/
err = 1;
goto error;
}
/*
* We only need to worry about colliding with an id
* that's already in use if this process has
* cycled through all available lwp ids.
*/
break;
}
/*
* If this is a branded process, let the brand do any necessary lwp
* initialization.
*/
if (PROC_IS_BRANDED(p)) {
err = 1;
goto error;
}
branded = 1;
}
if (t->t_tid == 1) {
if (p->p_tr_lgrpid != LGRP_NONE &&
p->p_tr_lgrpid != p->p_t1_lgrpid) {
}
}
p->p_lwpcnt++;
t->t_waitfor = -1;
/*
* Turn microstate accounting on for thread if on for process.
*/
t->t_proc_flag |= TP_MSACCT;
/*
* If the process has watchpoints, mark the new thread as such.
*/
if (pr_watch_active(p))
watch_enable(t);
/*
* The lwp is being created in the stopped state.
* We set all the necessary flags to indicate that fact here.
* We omit the TS_CREATE flag from t_schedflag so that the lwp
* cannot be set running until the caller is finished with it,
* even if lwp_continue() is called on it after we drop p->p_lock.
* When the caller is finished with the newly-created lwp,
* the caller must call lwp_create_done() to allow the lwp
* to be set running. If the TP_HOLDLWP is left set, the
* lwp will suspend itself after reaching system call exit.
*/
init_mstate(t, LMS_STOPPED);
t->t_proc_flag |= TP_HOLDLWP;
t->t_whystop = PR_SUSPENDED;
t->t_whatstop = SUSPEND_NORMAL;
/*
* Set system call processing flags in case tracing or profiling
* is set. The first system call will evaluate these and turn
* them off if they aren't needed.
*/
t->t_pre_sys = 1;
t->t_post_sys = 1;
/*
* Insert the new thread into the list of all threads.
*/
t->t_back = t;
t->t_forw = t;
p->p_tlist = t;
} else {
}
/*
* Insert the new lwp into an lwp directory slot position
* and into the lwpid hash table.
*/
/*
* We set the new lwp running immediately.
*/
t->t_proc_flag &= ~TP_HOLDLWP;
lwp_create_done(t);
}
if (err) {
if (CLASS_KERNEL(cid)) {
/*
* This should only happen if a system process runs
* out of lwpids, which shouldn't occur.
*/
panic("Failed to create a system LWP");
}
/*
* We have failed to create an lwp, so decrement the number
* of lwps in the task and let the lgroup load averages know
* that this thread isn't going to show up.
*/
p->p_zone->zone_nlwps--;
if (branded)
mutex_exit(&p->p_lock);
thread_rele(t);
/*
* We need to remove t from the list of all threads
* because thread_exit()/lwp_exit() isn't called on t.
*/
thread_free(t);
} else {
mutex_exit(&p->p_lock);
}
if (ret_tidhash != NULL)
return (lwp);
}
/*
* lwp_create_done() is called by the caller of lwp_create() to set the
* newly-created lwp running after the caller has finished manipulating it.
*/
void
{
/*
* We set the TS_CREATE and TS_CSTART flags and call setrun_locked().
* (The absence of the TS_CREATE flag prevents the lwp from running
* until we are finished with it, even if lwp_continue() is called on
* it by some other lwp in the process or elsewhere in the kernel.)
*/
thread_lock(t);
/*
* If TS_CSTART is set, lwp_continue(t) has been called and
* has already incremented p_lwprcnt; avoid doing this twice.
*/
if (!(t->t_schedflag & TS_CSTART))
p->p_lwprcnt++;
setrun_locked(t);
thread_unlock(t);
}
/*
* Copy an LWP's active templates, and clear the latest contracts.
*/
void
{
int i;
for (i = 0; i < ct_ntypes; i++) {
}
}
/*
* Clear an LWP's contract template state.
*/
void
{
int i;
for (i = 0; i < ct_ntypes; i++) {
}
}
}
}
/*
* Individual lwp exit.
* If this is the last lwp, exit the whole process.
*/
void
lwp_exit(void)
{
mutex_exit(&p->p_lock);
#if defined(__sparc)
/*
* Ensure that the user stack is fully abandoned..
*/
#endif
tsd_exit(); /* free thread specific data */
kcpc_passivate(); /* Clean up performance counter state */
pollcleanup();
if (t->t_door)
door_slam();
if (t->t_schedctl != NULL)
if (t->t_upimutex != NULL)
/*
* Perform any brand specific exit processing, then release any
* brand data associated with the lwp
*/
if (PROC_IS_BRANDED(p))
mutex_enter(&p->p_lock);
lwp_cleanup();
/*
* When this process is dumping core, its lwps are held here
* until the core dump is finished. Then exitlwps() is called
* again to release these lwps so that they can finish exiting.
*/
/*
* Block the process against /proc now that we have really acquired
* p->p_lock (to decrement p_lwpcnt and manipulate p_tlist at least).
*/
prbarrier(p);
/*
* Call proc_exit() if this is the last non-daemon lwp in the process.
*/
if (!(t->t_proc_flag & TP_DAEMON) &&
mutex_exit(&p->p_lock);
if (proc_exit(CLD_EXITED, 0) == 0) {
/* Restarting init. */
return;
}
/*
* proc_exit() returns a non-zero value when some other
* lwp got there first. We just have to continue in
* lwp_exit().
*/
mutex_enter(&p->p_lock);
prbarrier(p);
}
/*
* If the lwp is a detached lwp or if the process is exiting,
* remove (lwp_hash_out()) the lwp from the lwp directory.
* Otherwise null out the lwp's le_thread pointer in the lwp
* directory so that other threads will see it as a zombie lwp.
*/
prlwpexit(t); /* notify /proc */
lwp_hash_out(p, t->t_tid);
else {
p->p_zombcnt++;
cv_broadcast(&p->p_lwpexit);
}
if (t->t_proc_flag & TP_DAEMON) {
p->p_lwpdaemon--;
t->t_proc_flag &= ~TP_DAEMON;
}
t->t_proc_flag &= ~TP_TWAIT;
/*
* Maintain accurate lwp count for task.max-lwps resource control.
*/
p->p_zone->zone_nlwps--;
CL_EXIT(t); /* tell the scheduler that t is exiting */
p->p_lwpcnt--;
/*
* If all remaining non-daemon lwps are waiting in lwp_wait(),
* wake them up so someone can return EDEADLK.
* (See the block comment preceeding lwp_wait().)
*/
cv_broadcast(&p->p_lwpexit);
t->t_proc_flag |= TP_LWPEXIT;
term_mstate(t);
#ifndef NPROBE
/* Kernel probe */
if (t->t_tnf_tpdp)
#endif /* NPROBE */
if (t == p->p_tlist)
/*
* Clean up the signal state.
*/
if (t->t_sigqueue != NULL)
sigdelq(p, t, 0);
}
thread_rele(t);
/*
* Terminated lwps are associated with process zero and are put onto
* death-row by resume(). Avoid preemption after resetting t->t_procp.
*/
t->t_preempt++;
exitctx(t);
exitpctx(p);
/*
* Notify the HAT about the change of address space
*/
hat_thread_exit(t);
/*
* When this is the last running lwp in this process and some lwp is
* waiting for this condition to become true, or this thread was being
* suspended, then the waiting lwp is awakened.
*
* Also, if the process is exiting, we may have a thread waiting in
* exitlwps() that needs to be notified.
*/
cv_broadcast(&p->p_holdlwps);
/*
* Need to drop p_lock so we can reacquire pidlock.
*/
mutex_exit(&p->p_lock);
lwp_pcb_exit();
/* never returns */
}
/*
* Cleanup function for an exiting lwp.
* Called both from lwp_exit() and from proc_exit().
* p->p_lock is repeatedly released and grabbed in this function.
*/
void
lwp_cleanup(void)
{
/* untimeout any lwp-bound realtime timers */
/*
* If this is the /proc agent lwp that is exiting, readjust p_lwpid
* so it appears that the agent never existed, and clear p_agenttp.
*/
if (t == p->p_agenttp) {
p->p_lwpid--;
}
/*
* Do lgroup bookkeeping to account for thread exiting.
*/
if (t->t_tid == 1) {
p->p_t1_lgrpid = LGRP_NONE;
}
lwp_ctmpl_clear(ttolwp(t));
}
int
lwp_suspend(kthread_t *t)
{
int tid;
/*
* Set the thread's TP_HOLDLWP flag so it will stop in holdlwp().
* If an lwp is stopping itself, there is no need to wait.
*/
top:
t->t_proc_flag |= TP_HOLDLWP;
if (t == curthread) {
t->t_sig_check = 1;
} else {
/*
* Make sure the lwp stops promptly.
*/
thread_lock(t);
t->t_sig_check = 1;
/*
* XXX Should use virtual stop like /proc does instead of
* XXX waking the thread to get it to stop.
*/
if (ISWAKEABLE(t) || ISWAITING(t)) {
setrun_locked(t);
}
/*
* Wait for lwp to stop
*/
while (!SUSPENDED(t)) {
/*
* Drop the thread lock before waiting and reacquire it
* afterwards, so the thread can change its t_state
* field.
*/
thread_unlock(t);
/*
* Check if aborted by exitlwps().
*/
lwp_exit();
/*
* Cooperate with jobcontrol signals and /proc stopping
* by calling cv_wait_sig() to wait for the target
* lwp to stop. Just using cv_wait() can lead to
* deadlock because, if some other lwp has stopped
* by either of these mechanisms, then p_lwprcnt will
* never become zero if we do a cv_wait().
*/
return (EINTR);
/*
* Check to see if thread died while we were
* waiting for it to suspend.
*/
return (ESRCH);
thread_lock(t);
/*
* If the TP_HOLDLWP flag went away, lwp_continue()
* or vfork() must have been called while we were
* waiting, so start over again.
*/
if ((t->t_proc_flag & TP_HOLDLWP) == 0) {
thread_unlock(t);
goto top;
}
}
thread_unlock(t);
}
return (0);
}
/*
* continue a lwp that's been stopped by lwp_suspend().
*/
void
{
t->t_proc_flag &= ~TP_HOLDLWP;
thread_lock(t);
if (SUSPENDED(t) &&
p->p_lwprcnt++;
t->t_schedflag |= TS_CSTART;
setrun_locked(t);
}
thread_unlock(t);
/*
* Wakeup anyone waiting for this thread to be suspended
*/
if (was_suspended)
cv_broadcast(&p->p_holdlwps);
}
/*
* ********************************
* Miscellaneous lwp routines *
* ********************************
*/
/*
* When a process is undergoing a forkall(), its p_flag is set to SHOLDFORK.
* This will cause the process's lwps to stop at a hold point. A hold
* point is where a kernel thread has a flat stack. This is at the
* return from a system call and at the return from a user level trap.
*
* When a process is undergoing a fork1() or vfork(), its p_flag is set to
* SHOLDFORK1. This will cause the process's lwps to stop at a modified
* hold point. The lwps in the process are not being cloned, so they
* are held at the usual hold points and also within issig_forreal().
* This has the side-effect that their system calls do not return
* showing EINTR.
*
* An lwp can also be held. This is identified by the TP_HOLDLWP flag on
* the thread. The TP_HOLDLWP flag is set in lwp_suspend(), where the active
* lwp is waiting for the target lwp to be stopped.
*/
void
holdlwp(void)
{
mutex_enter(&p->p_lock);
/*
* Don't terminate immediately if the process is dumping core.
* Once the process has dumped core, all lwps are terminated.
*/
lwp_exit();
}
mutex_exit(&p->p_lock);
return;
}
/*
* stop() decrements p->p_lwprcnt and cv_signal()s &p->p_holdlwps
* when p->p_lwprcnt becomes zero.
*/
lwp_exit();
mutex_exit(&p->p_lock);
}
/*
* Have all lwps within the process hold at a point where they are
* cloneable (SHOLDFORK) or just safe w.r.t. fork1 (SHOLDFORK1).
*/
int
{
mutex_enter(&p->p_lock);
/*
* If another lwp is doing a forkall() or proc_exit(), bail out.
*/
mutex_exit(&p->p_lock);
return (0);
}
/*
* Another lwp is doing a fork1() or is undergoing
* watchpoint activity. We hold here for it to complete.
*/
}
pokelwps(p);
--p->p_lwprcnt;
/*
* Wait for the process to become quiescent (p->p_lwprcnt == 0).
*/
while (p->p_lwprcnt > 0) {
/*
* Check if aborted by exitlwps().
* Also check if SHOLDWATCH is set; it takes precedence.
*/
p->p_lwprcnt++;
cv_broadcast(&p->p_holdlwps);
goto again;
}
/*
* Cooperate with jobcontrol signals and /proc stopping.
* If some other lwp has stopped by either of these
* mechanisms, then p_lwprcnt will never become zero
* and the process will appear deadlocked unless we
* stop here in sympathy with the other lwp before
* doing the cv_wait() below.
*
* If the other lwp stops after we do the cv_wait(), it
* will wake us up to loop around and do the sympathy stop.
*
* Since stop() drops p->p_lock, we must start from
* the top again on returning from stop().
*/
p->p_lwprcnt++;
goto again;
}
}
p->p_lwprcnt++;
mutex_exit(&p->p_lock);
return (1);
}
/*
* See comments for holdwatch(), below.
*/
static int
holdcheck(int clearflags)
{
/*
* If we are trying to exit, that takes precedence over anything else.
*/
p->p_lwprcnt++;
p->p_flag &= ~clearflags;
lwp_exit();
}
/*
* If another thread is calling fork1(), stop the current thread so the
* other can complete.
*/
if (p->p_flag & SHOLDFORK1) {
p->p_lwprcnt++;
p->p_flag &= ~clearflags;
lwp_exit();
}
return (-1);
}
/*
* If another thread is calling fork(), then indicate we are doing
* watchpoint activity. This will cause holdlwps() above to stop the
* forking thread, at which point we can continue with watchpoint
* activity.
*/
p->p_lwprcnt++;
p->p_flag |= SHOLDWATCH;
cv_broadcast(&p->p_holdlwps);
p->p_flag &= ~SHOLDWATCH;
}
return (-1);
}
return (0);
}
/*
* Stop all lwps within the process, holding themselves in the kernel while the
* active lwp undergoes watchpoint activity. This is more complicated than
* expected because stop() relies on calling holdwatch() in order to copyin data
* from the user's address space. A double barrier is used to prevent an
* infinite loop.
*
* o The first thread into holdwatch() is the 'master' thread and does
* the following:
*
* - Sets SHOLDWATCH on the current process
* - Sets TP_WATCHSTOP on the current thread
* - Waits for all threads to be either stopped or have
* TP_WATCHSTOP set.
* - Sets the SWATCHOK flag on the process
* - Unsets TP_WATCHSTOP
* - Waits for the other threads to completely stop
* - Unsets SWATCHOK
*
* o If SHOLDWATCH is already set when we enter this function, then another
* thread is already trying to stop this thread. This 'slave' thread
* does the following:
*
* - Sets TP_WATCHSTOP on the current thread
* - Waits for SWATCHOK flag to be set
* - Calls stop()
*
* o If SWATCHOK is set on the process, then this function immediately
* returns, as we must have been called via stop().
*
* In addition, there are other flags that take precedence over SHOLDWATCH:
*
* o If SEXITLWPS is set, exit immediately.
*
* o If SHOLDFORK1 is set, wait for fork1() to complete.
*
* o If SHOLDFORK is set, then watchpoint activity takes precedence In this
* case, set SHOLDWATCH, signalling the forking thread to stop first.
*
* o If the process is being stopped via /proc (TP_PRSTOP is set), then we
* stop the current thread.
*
* Returns 0 if all threads have been quiesced. Returns non-zero if not all
* threads were stopped, or the list of watched pages has changed.
*/
int
holdwatch(void)
{
int ret = 0;
mutex_enter(&p->p_lock);
p->p_lwprcnt--;
/*
* Check for bail-out conditions as outlined above.
*/
if (holdcheck(0) != 0) {
mutex_exit(&p->p_lock);
return (-1);
}
if (!(p->p_flag & SHOLDWATCH)) {
/*
* We are the master watchpoint thread. Set SHOLDWATCH and poke
* the other threads.
*/
p->p_flag |= SHOLDWATCH;
pokelwps(p);
/*
* Wait for all threads to be stopped or have TP_WATCHSTOP set.
*/
while (pr_allstopped(p, 1) > 0) {
if (holdcheck(SHOLDWATCH) != 0) {
p->p_flag &= ~SHOLDWATCH;
mutex_exit(&p->p_lock);
return (-1);
}
}
/*
* All threads are now stopped or in the process of stopping.
* Set SWATCHOK and let them stop completely.
*/
t->t_proc_flag &= ~TP_WATCHSTOP;
cv_broadcast(&p->p_holdlwps);
while (pr_allstopped(p, 0) > 0) {
/*
* At first glance, it may appear that we don't need a
* call to holdcheck() here. But if the process gets a
* SIGKILL signal, one of our stopped threads may have
* been awakened and is waiting in exitlwps(), which
* takes precedence over watchpoints.
*/
mutex_exit(&p->p_lock);
return (-1);
}
}
/*
* All threads are now completely stopped.
*/
p->p_flag &= ~SHOLDWATCH;
p->p_lwprcnt++;
/*
* SHOLDWATCH is set, so another thread is trying to do
* watchpoint activity. Indicate this thread is stopping, and
* wait for the OK from the master thread.
*/
t->t_proc_flag |= TP_WATCHSTOP;
cv_broadcast(&p->p_holdlwps);
if (holdcheck(0) != 0) {
t->t_proc_flag &= ~TP_WATCHSTOP;
mutex_exit(&p->p_lock);
return (-1);
}
}
/*
* Once the master thread has given the OK, this thread can
* actually call stop().
*/
t->t_proc_flag &= ~TP_WATCHSTOP;
p->p_lwprcnt++;
/*
* It's not OK to do watchpoint activity, notify caller to
* retry.
*/
ret = -1;
} else {
/*
* The only way we can hit the case where SHOLDWATCH is set and
* SWATCHOK is set is if we are triggering this from within a
* stop() call. Assert that this is the case.
*/
p->p_lwprcnt++;
}
mutex_exit(&p->p_lock);
return (ret);
}
/*
* force all interruptible lwps to trap into the kernel.
*/
void
{
kthread_t *t;
t = p->p_tlist;
do {
if (t == curthread)
continue;
thread_lock(t);
aston(t); /* make thread trap or do post_syscall */
if (ISWAKEABLE(t) || ISWAITING(t)) {
setrun_locked(t);
} else if (t->t_state == TS_STOPPED) {
/*
* Ensure that proc_exit() is not blocked by lwps
* that were stopped via jobcontrol or /proc.
*/
p->p_stopsig = 0;
setrun_locked(t);
}
/*
* If we are holding lwps for a forkall(),
* force lwps that have been suspended via
* lwp_suspend() and are suspended inside
* of a system call to proceed to their
* holdlwp() points where they are clonable.
*/
if ((t->t_schedflag & TS_CSTART) == 0) {
p->p_lwprcnt++;
t->t_schedflag |= TS_CSTART;
setrun_locked(t);
}
}
}
thread_unlock(t);
}
/*
* undo the effects of holdlwps() or holdwatch().
*/
void
continuelwps(proc_t *p)
{
kthread_t *t;
/*
* If this flag is set, then the original holdwatch() didn't actually
* stop the process. See comments for holdwatch().
*/
return;
}
t = p->p_tlist;
do {
thread_lock(t); /* SUSPENDED looks at t_schedflag */
p->p_lwprcnt++;
t->t_schedflag |= TS_CSTART;
setrun_locked(t);
}
thread_unlock(t);
}
/*
* Force all other LWPs in the current process other than the caller to exit,
* and then cv_wait() on p_holdlwps for them to exit. The exitlwps() function
* is typically used in these situations:
*
* (a) prior to an exec() system call
* (b) prior to dumping a core file
* (c) prior to a uadmin() shutdown
*
* If the 'coredump' flag is set, other LWPs are quiesced but not destroyed.
* Multiple threads in the process can call this function at one time by
* triggering execs or core dumps simultaneously, so the SEXITLWPS bit is used
* to declare one particular thread the winner who gets to kill the others.
* If a thread wins the exitlwps() dance, zero is returned; otherwise an
* appropriate errno value is returned to caller for its system call to return.
*/
int
{
int heldcnt;
door_slam();
if (p->p_door_list)
/*
* Ensure that before starting to wait for other lwps to exit,
* cleanup all upimutexes held by curthread. Otherwise, some other
* lwp could be waiting (uninterruptibly) for a upimutex held by
* curthread, and the call to pokelwps() below would deadlock.
* Even if a blocked upimutex_lock is made interruptible,
* curthread's upimutexes need to be unlocked: do it here.
*/
/*
* Grab p_lock in order to check and set SEXITLWPS to declare a winner.
* We must also block any further /proc access from this point forward.
*/
mutex_enter(&p->p_lock);
prbarrier(p);
mutex_exit(&p->p_lock);
}
if (coredump) /* tell other lwps to stop, not exit */
/*
* Give precedence to exitlwps() if a holdlwps() is
* in progress. The lwp doing the holdlwps() operation
* is aborted when it is awakened.
*/
cv_broadcast(&p->p_holdlwps);
prbarrier(p);
}
pokelwps(p);
/*
* Wait for process to become quiescent.
*/
--p->p_lwprcnt;
while (p->p_lwprcnt > 0) {
prbarrier(p);
}
p->p_lwprcnt++;
/*
* The SCOREDUMP flag puts the process into a quiescent
* state. The process's lwps remain attached to this
* process until exitlwps() is called again without the
* 'coredump' flag set, then the lwps are terminated
* and the process can exit.
*/
if (coredump) {
goto out;
}
/*
* Determine if there are any lwps left dangling in
* the stopped state. This happens when exitlwps()
* aborts a holdlwps() operation.
*/
kthread_t *t;
t->t_proc_flag &= ~TP_TWAIT;
lwp_continue(t);
}
}
/*
* Wait for all other lwps to exit.
*/
--p->p_lwprcnt;
while (p->p_lwpcnt > 1) {
prbarrier(p);
}
++p->p_lwprcnt;
out:
int i;
p->p_zombcnt--;
}
}
}
/*
* If some other LWP in the process wanted us to suspend ourself,
* then we will not do it. The other LWP is now terminated and
* no one will ever continue us again if we suspend ourself.
*/
mutex_exit(&p->p_lock);
return (0);
}
/*
* duplicate a lwp.
*/
klwp_t *
{
int cid;
void *bufp;
void *brand_data;
int val;
#if defined(__sparc)
if (t == curthread)
(void) flush_user_windows_to_stack(NULL);
#endif
if (t == curthread)
/* copy args out of registers first */
(void) save_syscall_args();
return (NULL);
/*
* most of the parent's lwp can be copied to its duplicate,
* except for the fields that are unique to each lwp, like
* lwp_thread, lwp_procp, lwp_regs, and lwp_ap.
*/
/*
* Copy parent lwp to child lwp. Hold child's p_lock to prevent
* mstate_aggr_state() from reading stale mstate entries copied
* from lwp to clwp.
*/
/* clear microstate and resource usage data in new lwp */
/* fix up child's lwp */
#if defined(__sparc)
#endif
clwp->lwp_cursig = 0;
clwp->lwp_extsig = 0;
clwp->lwp_lastfault = 0;
clwp->lwp_lastfaddr = 0;
/* copy parent's struct regs to child. */
/*
* Fork thread context ops, if any.
*/
if (t->t_ctx)
/* fix door state in the child */
if (t->t_door)
/* copy current contract templates, clear latest contracts */
/* lwp_create() set the TP_HOLDLWP flag */
if (!(t->t_proc_flag & TP_HOLDLWP))
/* Allow brand to propagate brand-specific state */
if (PROC_IS_BRANDED(p))
mutex_enter(&p->p_lock);
/*
* Someone just changed this thread's scheduling class,
* so try pre-allocating the buffer again. Hopefully we
* don't hit this often.
*/
mutex_exit(&p->p_lock);
goto retry;
}
mutex_exit(&p->p_lock);
return (clwp);
}
/*
* Add a new lwp entry to the lwp directory and to the lwpid hash table.
*/
void
int do_lock)
{
kthread_t *t;
/*
* Allocate a directory element from the free list.
* Code elsewhere guarantees a free slot.
*/
if (do_lock)
/*
* Insert it into the lwpid hash table.
*/
/*
* Set the active thread's directory slot entry.
*/
}
if (do_lock)
}
/*
* Remove an lwp from the lwpid hash table and free its directory entry.
* This is done when a detached lwp exits in lwp_exit() or
* when a non-detached lwp is waited for in lwp_wait() or
* when a zombie lwp is detached in lwp_detach().
*/
void
{
break;
}
}
}
/*
* Lookup an lwp in the lwpid hash table by lwpid.
*/
lwpdir_t *
{
/*
* The process may be exiting, after p_tidhash has been set to NULL in
* proc_exit() but before prfee() has been called. Return failure in
* this case.
*/
return (NULL);
return (ldp);
}
return (NULL);
}
/*
* Same as lwp_hash_lookup(), but acquire and return
* the tid hash table entry lock on success.
*/
lwpdir_t *
{
top:
tidhash_sz = p->p_tidhash_sz;
return (NULL);
/*
* Since we are not holding p->p_lock, the tid hash table
* may have changed. If so, start over. If not, then
* it cannot change until after we drop &thp->th_lock;
*/
goto top;
}
return (ldp);
}
}
return (NULL);
}
/*
* Update the indicated LWP usage statistic for the current LWP.
*/
void
{
return;
switch (lwp_stat_id) {
case LWP_STAT_INBLK:
break;
case LWP_STAT_OUBLK:
break;
case LWP_STAT_MSGRCV:
break;
case LWP_STAT_MSGSND:
break;
default:
}
}