dt_proc.c

来自「Sun Solaris 10 中的 DTrace 组件的源代码。请参看: htt」· C语言 代码 · 共 1,011 行 · 第 1/3 页

	for (npr = *npp; npr != NULL; npr = npr->dpr_notify) {
		if (npr != dpr)
			npp = &npr->dpr_notify;
		else
			break;
	}

	if (npr != NULL) {
		*npp = npr->dpr_notify;
		npr->dpr_notify = NULL;
	}

	(void) pthread_mutex_unlock(&dph->dph_lock);

	/*
	 * Remove the dt_proc_list from the LRU list, release the underlying
	 * libproc handle, and free our dt_proc_t data structure.
	 */
	if (dpr->dpr_cacheable) {
		assert(dph->dph_lrucnt != 0);
		dph->dph_lrucnt--;
	}

	dt_list_delete(&dph->dph_lrulist, dpr);
	Prelease(dpr->dpr_proc, rflag);
	dt_free(dtp, dpr);
}

static int
dt_proc_create_thread(dt_proc_t *dpr, uint_t stop)
{
	sigset_t nset, oset;
	pthread_attr_t a;
	int err;

	(void) pthread_mutex_lock(&dpr->dpr_lock);
	dpr->dpr_stop |= stop; /* set bit for initial rendezvous */

	(void) pthread_attr_init(&a);
	(void) pthread_attr_setdetachstate(&a, PTHREAD_CREATE_DETACHED);

	(void) sigfillset(&nset);
	(void) sigdelset(&nset, SIGABRT);	/* unblocked for assert() */
	(void) sigdelset(&nset, SIGCANCEL);	/* see dt_proc_destroy() */

	(void) pthread_sigmask(SIG_SETMASK, &nset, &oset);
	err = pthread_create(&dpr->dpr_tid, &a, dt_proc_control, dpr);
	(void) pthread_sigmask(SIG_SETMASK, &oset, NULL);

	/*
	 * If the control thread was created, then wait on dpr_cv for either
	 * dpr_done to be set (the victim died or the control thread failed)
	 * or DT_PROC_STOP_IDLE to be set, indicating that the victim is now
	 * stopped by /proc and the control thread is at the rendezvous event.
	 * On success, we return with the process and control thread stopped:
	 * the caller can then apply dt_proc_continue() to resume both.
	 */
	if (err == 0) {
		while (!dpr->dpr_done && !(dpr->dpr_stop & DT_PROC_STOP_IDLE))
			(void) pthread_cond_wait(&dpr->dpr_cv, &dpr->dpr_lock);

		/*
		 * If dpr_done is set, the control thread aborted before it
		 * reached the rendezvous event.  This is either due to PS_LOST
		 * or PS_UNDEAD (i.e. the process died).  We try to provide a
		 * small amount of useful information to help figure it out.
		 */
		if (dpr->dpr_done) {
			const psinfo_t *prp = Ppsinfo(dpr->dpr_proc);
			int stat = prp ? prp->pr_wstat : 0;
			int pid = dpr->dpr_pid;

			if (Pstate(dpr->dpr_proc) == PS_LOST) {
				(void) dt_proc_error(dpr->dpr_hdl, dpr,
				    "failed to control pid %d: process exec'd "
				    "set-id or unobservable program\n", pid);
			} else if (WIFSIGNALED(stat)) {
				(void) dt_proc_error(dpr->dpr_hdl, dpr,
				    "failed to control pid %d: process died "
				    "from signal %d\n", pid, WTERMSIG(stat));
			} else {
				(void) dt_proc_error(dpr->dpr_hdl, dpr,
				    "failed to control pid %d: process exited "
				    "with status %d\n", pid, WEXITSTATUS(stat));
			}

			err = ESRCH; /* cause grab() or create() to fail */
		} else {
			/*
			 * Disable breakpoints while the process is stopped so
			 * the pid provider can correctly disassemble all
			 * functions.
			 */
			dt_proc_bpdisable(dpr);
		}

	} else {
		(void) dt_proc_error(dpr->dpr_hdl, dpr,
		    "failed to create control thread for process-id %d: %s\n",
		    (int)dpr->dpr_pid, strerror(err));
	}

	(void) pthread_mutex_unlock(&dpr->dpr_lock);
	(void) pthread_attr_destroy(&a);

	return (err);
}

struct ps_prochandle *
dt_proc_create(dtrace_hdl_t *dtp, const char *file, char *const *argv)
{
	dt_proc_hash_t *dph = dtp->dt_procs;
	dt_proc_t *dpr;
	int err;

	if ((dpr = dt_zalloc(dtp, sizeof (dt_proc_t))) == NULL)
		return (NULL); /* errno is set for us */

	(void) pthread_mutex_init(&dpr->dpr_lock, NULL);
	(void) pthread_cond_init(&dpr->dpr_cv, NULL);

	if ((dpr->dpr_proc = Pcreate(file, argv, &err, NULL, 0)) == NULL) {
		return (dt_proc_error(dtp, dpr,
		    "failed to execute %s: %s\n", file, Pcreate_error(err)));
	}

	dpr->dpr_hdl = dtp;
	dpr->dpr_pid = Pstatus(dpr->dpr_proc)->pr_pid;

	(void) Punsetflags(dpr->dpr_proc, PR_RLC);
	(void) Psetflags(dpr->dpr_proc, PR_KLC);

	if (dt_proc_create_thread(dpr, dtp->dt_prcmode) != 0)
		return (NULL); /* dt_proc_error() has been called for us */

	dpr->dpr_hash = dph->dph_hash[dpr->dpr_pid & (dph->dph_hashlen - 1)];
	dph->dph_hash[dpr->dpr_pid & (dph->dph_hashlen - 1)] = dpr;
	dt_list_prepend(&dph->dph_lrulist, dpr);

	dt_dprintf("created pid %d\n", (int)dpr->dpr_pid);
	dpr->dpr_refs++;

	return (dpr->dpr_proc);
}

struct ps_prochandle *
dt_proc_grab(dtrace_hdl_t *dtp, pid_t pid, int flags, int nomonitor)
{
	dt_proc_hash_t *dph = dtp->dt_procs;
	uint_t h = pid & (dph->dph_hashlen - 1);
	dt_proc_t *dpr, *opr;
	int err;

	/*
	 * Search the hash table for the pid.  If it is already grabbed or
	 * created, move the handle to the front of the lrulist, increment
	 * the reference count, and return the existing ps_prochandle.
	 */
	for (dpr = dph->dph_hash[h]; dpr != NULL; dpr = dpr->dpr_hash) {
		if (dpr->dpr_pid == pid) {
			dt_dprintf("grabbed pid %d (cached)\n", (int)pid);
			dt_list_delete(&dph->dph_lrulist, dpr);
			dt_list_prepend(&dph->dph_lrulist, dpr);
			dpr->dpr_refs++;
			return (dpr->dpr_proc);
		}
	}

	if ((dpr = dt_zalloc(dtp, sizeof (dt_proc_t))) == NULL)
		return (NULL); /* errno is set for us */

	(void) pthread_mutex_init(&dpr->dpr_lock, NULL);
	(void) pthread_cond_init(&dpr->dpr_cv, NULL);

	if ((dpr->dpr_proc = Pgrab(pid, flags, &err)) == NULL) {
		return (dt_proc_error(dtp, dpr,
		    "failed to grab pid %d: %s\n", (int)pid, Pgrab_error(err)));
	}

	dpr->dpr_hdl = dtp;
	dpr->dpr_pid = pid;

	(void) Punsetflags(dpr->dpr_proc, PR_KLC);
	(void) Psetflags(dpr->dpr_proc, PR_RLC);

	/*
	 * If we are attempting to grab the process without a monitor
	 * thread, then mark the process as cacheable.  If we're currently
	 * caching more process handles than dph_lrulim permits, attempt to
	 * find the least-recently-used handle that is currently
	 * unreferenced and release it from the cache.  Otherwise we are
	 * grabbing the process for control: create a control thread for
	 * this process and store its ID in dpr->dpr_tid.
	 */
	if (nomonitor || (flags & PGRAB_RDONLY)) {
		if (dph->dph_lrucnt >= dph->dph_lrulim) {
			for (opr = dt_list_prev(&dph->dph_lrulist);
			    opr != NULL; opr = dt_list_prev(opr)) {
				if (opr->dpr_cacheable && opr->dpr_refs == 0) {
					dt_proc_destroy(dtp, opr->dpr_proc);
					break;
				}
			}
		}

		if (flags & PGRAB_RDONLY) {
			dpr->dpr_cacheable = B_TRUE;
			dph->dph_lrucnt++;
		}

	} else if (dt_proc_create_thread(dpr, DT_PROC_STOP_GRAB) != 0)
		return (NULL); /* dt_proc_error() has been called for us */

	dpr->dpr_hash = dph->dph_hash[h];
	dph->dph_hash[h] = dpr;
	dt_list_prepend(&dph->dph_lrulist, dpr);

	dt_dprintf("grabbed pid %d\n", (int)pid);
	dpr->dpr_refs++;

	return (dpr->dpr_proc);
}

void
dt_proc_release(dtrace_hdl_t *dtp, struct ps_prochandle *P)
{
	dt_proc_t *dpr = dt_proc_lookup(dtp, P, B_FALSE);
	dt_proc_hash_t *dph = dtp->dt_procs;

	assert(dpr != NULL);
	assert(dpr->dpr_refs != 0);

	if (--dpr->dpr_refs == 0 &&
	    (!dpr->dpr_cacheable || dph->dph_lrucnt > dph->dph_lrulim))
		dt_proc_destroy(dtp, P);
}

void
dt_proc_continue(dtrace_hdl_t *dtp, struct ps_prochandle *P)
{
	dt_proc_t *dpr = dt_proc_lookup(dtp, P, B_FALSE);

	(void) pthread_mutex_lock(&dpr->dpr_lock);

	if (dpr->dpr_stop & DT_PROC_STOP_IDLE) {
		/*
		 * Breakpoints are disabled while the process is stopped so
		 * the pid provider can correctly disassemble all functions.
		 */
		dt_proc_bpenable(dpr);
		dpr->dpr_stop &= ~DT_PROC_STOP_IDLE;
		(void) pthread_cond_broadcast(&dpr->dpr_cv);
	}

	(void) pthread_mutex_unlock(&dpr->dpr_lock);
}

void
dt_proc_lock(dtrace_hdl_t *dtp, struct ps_prochandle *P)
{
	dt_proc_t *dpr = dt_proc_lookup(dtp, P, B_FALSE);
	int err = pthread_mutex_lock(&dpr->dpr_lock);
	assert(err == 0); /* check for recursion */
}

void
dt_proc_unlock(dtrace_hdl_t *dtp, struct ps_prochandle *P)
{
	dt_proc_t *dpr = dt_proc_lookup(dtp, P, B_FALSE);
	int err = pthread_mutex_unlock(&dpr->dpr_lock);
	assert(err == 0); /* check for unheld lock */
}

void
dt_proc_hash_create(dtrace_hdl_t *dtp)
{
	if ((dtp->dt_procs = dt_zalloc(dtp, sizeof (dt_proc_hash_t) +
	    sizeof (dt_proc_t *) * _dtrace_pidbuckets - 1)) != NULL) {

		(void) pthread_mutex_init(&dtp->dt_procs->dph_lock, NULL);
		(void) pthread_cond_init(&dtp->dt_procs->dph_cv, NULL);

		dtp->dt_procs->dph_hashlen = _dtrace_pidbuckets;
		dtp->dt_procs->dph_lrulim = _dtrace_pidlrulim;
	}
}

void
dt_proc_hash_destroy(dtrace_hdl_t *dtp)
{
	dt_proc_hash_t *dph = dtp->dt_procs;
	dt_proc_t *dpr;

	while ((dpr = dt_list_next(&dph->dph_lrulist)) != NULL)
		dt_proc_destroy(dtp, dpr->dpr_proc);

	dtp->dt_procs = NULL;
	dt_free(dtp, dph);
}

struct ps_prochandle *
dtrace_proc_create(dtrace_hdl_t *dtp, const char *file, char *const *argv)
{
	dt_ident_t *idp = dt_idhash_lookup(dtp->dt_macros, "target");
	struct ps_prochandle *P = dt_proc_create(dtp, file, argv);

	if (P != NULL && idp != NULL && idp->di_id == 0)
		idp->di_id = Pstatus(P)->pr_pid; /* $target = created pid */

	return (P);
}

struct ps_prochandle *
dtrace_proc_grab(dtrace_hdl_t *dtp, pid_t pid, int flags)
{
	dt_ident_t *idp = dt_idhash_lookup(dtp->dt_macros, "target");
	struct ps_prochandle *P = dt_proc_grab(dtp, pid, flags, 0);

	if (P != NULL && idp != NULL && idp->di_id == 0)
		idp->di_id = pid; /* $target = grabbed pid */

	return (P);
}

void
dtrace_proc_release(dtrace_hdl_t *dtp, struct ps_prochandle *P)
{
	dt_proc_release(dtp, P);
}

void
dtrace_proc_continue(dtrace_hdl_t *dtp, struct ps_prochandle *P)
{
	dt_proc_continue(dtp, P);
}