From: Alan Cox <alan@linux.intel.com>
Date: Mon, 21 Jan 2019 22:19:23 +0000 (+0000)
Subject: preemption: allow pre-emption where the leaving processis marked STOPPED
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=ea75fb6732f27d02985c52d5eebcf956b7e0da59;p=FUZIX.git

preemption: allow pre-emption where the leaving processis marked STOPPED

We need this to make SIGSTOP work reliably and properly
---

diff --git a/Kernel/lowlevel-65c816.s b/Kernel/lowlevel-65c816.s
index 397fa325..4f26b3ee 100644
--- a/Kernel/lowlevel-65c816.s
+++ b/Kernel/lowlevel-65c816.s
@@ -634,8 +634,12 @@ ret_to_user:
 	;	Mark outselves as idle
 	;
 	ldx	U_DATA__U_PTAB
+	lda	a:P_TAB__P_STATUS_OFFSET,x
+	cmp	#P_RUNNING
+	bne	not_running
 	lda	#P_READY
 	sta	a:P_TAB__P_STATUS_OFFSET,x
+not_running:
 	;
 	;	Drop back to a8i8 and schedule ourself out
 	;
diff --git a/Kernel/lowlevel-6809.s b/Kernel/lowlevel-6809.s
index 21d5e6c7..75ef71d8 100644
--- a/Kernel/lowlevel-6809.s
+++ b/Kernel/lowlevel-6809.s
@@ -249,8 +249,12 @@ in_kernel:
 	;
 	ldx U_DATA__U_PTAB
 	; Move to ready state
+	lda P_TAB__P_STATUS_OFFSET,x
+	cmpa #P_RUNNING
+	bne not_running
 	lda #P_READY
 	sta P_TAB__P_STATUS_OFFSET,x
+not_running:
 	; Sleep on the kernel stack, IRQs will get re-enabled if need
 	; be
 	jsr _platform_switchout
diff --git a/Kernel/lowlevel-68hc11.s b/Kernel/lowlevel-68hc11.s
index 01838154..83568529 100644
--- a/Kernel/lowlevel-68hc11.s
+++ b/Kernel/lowlevel-68hc11.s
@@ -149,8 +149,12 @@ interrupt_handler:
 	lds #kstack_top
 	jsr chksigs
 	ldx U_DATA__U_PTAB
+	ldab P_TAB__P_STATUS_OFFSET,x
+	cmpb #P_RUNNING
+	bne not_running
 	ldab #P_READY
 	stab P_TAB__P_STATUS_OFFSET,x
+not_running:
 	jsr platform_switchout
 	jsr map_process_always
 	; caller will switch back to stack in X
diff --git a/Kernel/lowlevel-z80-banked.s b/Kernel/lowlevel-z80-banked.s
index f6ad820d..d7b5a7f2 100644
--- a/Kernel/lowlevel-z80-banked.s
+++ b/Kernel/lowlevel-z80-banked.s
@@ -548,7 +548,11 @@ intret2:di
 	; Process status is offset 0
 	;
 	ld hl, (U_DATA__U_PTAB)
+	ld a, #P_RUNNING
+	cp (hl)
+	jr nz, not_running
 	ld (hl), #P_READY
+not_running:
 	call _platform_switchout
 	;
 	; We are no longer in an interrupt or a syscall
diff --git a/Kernel/lowlevel-z80-thunked.s b/Kernel/lowlevel-z80-thunked.s
index 4ebdff65..bd464885 100644
--- a/Kernel/lowlevel-z80-thunked.s
+++ b/Kernel/lowlevel-z80-thunked.s
@@ -304,7 +304,11 @@ intret2:
 	ld (U_DATA__U_INSYS),a
 	call _chksigs
 	ld hl, (U_DATA__U_PTAB)
+	ld a,#P_RUNNING
+	cp (hl)
+	jr nz, not_running
 	ld (hl), #P_READY
+not_running:
 	; Give up the CPU
 	; FIXME: can we get here on timers when only one thing is running
 	; and we don't need to pre-empt ????? Is this more generally busted
diff --git a/Kernel/lowlevel-z80.s b/Kernel/lowlevel-z80.s
index db6476f1..c2bc78ff 100644
--- a/Kernel/lowlevel-z80.s
+++ b/Kernel/lowlevel-z80.s
@@ -567,7 +567,11 @@ intret2:call map_kernel_di
 	; Process status is offset 0
 	;
 	ld hl, (U_DATA__U_PTAB)
+	ld a,#P_RUNNING
+	cp (hl)
+	jr nz, not_running
 	ld (hl), #P_READY
+not_running:
 	call _platform_switchout
 	;
 	; We are no longer in an interrupt or a syscall