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Date:      Wed, 11 Nov 2020 08:48:43 +0000 (UTC)
From:      Mateusz Guzik <mjg@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r367583 - in head/sys: kern sys
Message-ID:  <202011110848.0AB8mhug062126@repo.freebsd.org>
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Author: mjg
Date: Wed Nov 11 08:48:43 2020
New Revision: 367583
URL: https://svnweb.freebsd.org/changeset/base/367583

Log:
  thread: fix thread0 tid allocation
  
  Startup code hardcodes the value instead of allocating it.
  The first spawned thread would then be a duplicate.
  
  Pointy hat:	mjg

Modified:
  head/sys/kern/init_main.c
  head/sys/kern/kern_thread.c
  head/sys/sys/proc.h

Modified: head/sys/kern/init_main.c
==============================================================================
--- head/sys/kern/init_main.c	Wed Nov 11 00:43:13 2020	(r367582)
+++ head/sys/kern/init_main.c	Wed Nov 11 08:48:43 2020	(r367583)
@@ -496,8 +496,7 @@ proc0_init(void *dummy __unused)
 	p->p_klist = knlist_alloc(&p->p_mtx);
 	STAILQ_INIT(&p->p_ktr);
 	p->p_nice = NZERO;
-	/* pid_max cannot be greater than PID_MAX */
-	td->td_tid = PID_MAX + 1;
+	td->td_tid = THREAD0_TID;
 	LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
 	td->td_state = TDS_RUNNING;
 	td->td_pri_class = PRI_TIMESHARE;

Modified: head/sys/kern/kern_thread.c
==============================================================================
--- head/sys/kern/kern_thread.c	Wed Nov 11 00:43:13 2020	(r367582)
+++ head/sys/kern/kern_thread.c	Wed Nov 11 08:48:43 2020	(r367583)
@@ -354,6 +354,7 @@ extern int max_threads_per_proc;
 void
 threadinit(void)
 {
+	lwpid_t tid0;
 	uint32_t flags;
 
 	/*
@@ -374,6 +375,9 @@ threadinit(void)
 
 	mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
 	tid_bitmap = bit_alloc(maxthread, M_TIDHASH, M_WAITOK);
+	tid0 = tid_alloc();
+	if (tid0 != THREAD0_TID)
+		panic("tid0 %d != %d\n", tid0, THREAD0_TID);
 
 	flags = UMA_ZONE_NOFREE;
 #ifdef __aarch64__

Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h	Wed Nov 11 00:43:13 2020	(r367582)
+++ head/sys/sys/proc.h	Wed Nov 11 08:48:43 2020	(r367583)
@@ -855,6 +855,7 @@ MALLOC_DECLARE(M_SUBPROC);
  */
 #define	PID_MAX		99999
 #define	NO_PID		100000
+#define	THREAD0_TID	NO_PID
 extern pid_t pid_max;
 
 #define	SESS_LEADER(p)	((p)->p_session->s_leader == (p))

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