Quick fix for bitrot in locking in the SMP case. cd_getreg() and

cd_setreg() were still using !(read_eflags() & PSL_I) as the condition
for the lock hidden by COM_LOCK() (if any) being held.  This worked
when spin mutexes and/or critical_enter() used hard interrupt disablement,
but it has caused recursion on the non-recursive mutex com_mtx since
all relevant interrupt disablement became soft.  The recursion is
harmless unless there are other bugs, but it breaks an invariant so
it is fatal if spinlocks are witnessed.

3 files changed, 72 insertions, 12 deletions

diff --git a/sys/dev/cy/cy.c b/sys/dev/cy/cy.c
index c8f2459..4bbedba 100644
--- a/sys/dev/cy/cy.c
+++ b/sys/dev/cy/cy.c
@@ -2852,6 +2852,9 @@ cd_getreg(com, reg)
 	int	cy_align;
 	register_t	eflags;
 	cy_addr	iobase;
+#ifdef SMP
+	int	need_unlock;
+#endif
 	int	val;
 
 	basecom = com_addr(com->unit & ~(CD1400_NO_OF_CHANNELS - 1));
@@ -2860,13 +2863,20 @@ cd_getreg(com, reg)
 	iobase = com->iobase;
 	eflags = read_eflags();
 	critical_enter();
-	if (eflags & PSL_I)
+#ifdef SMP
+	need_unlock = 0;
+	if (!mtx_owned(&com_mtx)) {
 		COM_LOCK();
+		need_unlock = 1;
+	}
+#endif
 	if (basecom->car != car)
 		cd_outb(iobase, CD1400_CAR, cy_align, basecom->car = car);
 	val = cd_inb(iobase, reg, cy_align);
-	if (eflags & PSL_I)
+#ifdef SMP
+	if (need_unlock)
 		COM_UNLOCK();
+#endif
 	critical_exit();
 	return (val);
 }
@@ -2882,6 +2892,9 @@ cd_setreg(com, reg, val)
 	int	cy_align;
 	register_t	eflags;
 	cy_addr	iobase;
+#ifdef SMP
+	int	need_unlock;
+#endif
 
 	basecom = com_addr(com->unit & ~(CD1400_NO_OF_CHANNELS - 1));
 	car = com->unit & CD1400_CAR_CHAN;
@@ -2889,13 +2902,20 @@ cd_setreg(com, reg, val)
 	iobase = com->iobase;
 	eflags = read_eflags();
 	critical_enter();
-	if (eflags & PSL_I)
+#ifdef SMP
+	need_unlock = 0;
+	if (!mtx_owned(&com_mtx)) {
 		COM_LOCK();
+		need_unlock = 1;
+	}
+#endif
 	if (basecom->car != car)
 		cd_outb(iobase, CD1400_CAR, cy_align, basecom->car = car);
 	cd_outb(iobase, reg, cy_align, val);
-	if (eflags & PSL_I)
+#ifdef SMP
+	if (need_unlock)
 		COM_UNLOCK();
+#endif
 	critical_exit();
 }
 
diff --git a/sys/dev/cy/cy_isa.c b/sys/dev/cy/cy_isa.c
index c8f2459..4bbedba 100644
--- a/sys/dev/cy/cy_isa.c
+++ b/sys/dev/cy/cy_isa.c
@@ -2852,6 +2852,9 @@ cd_getreg(com, reg)
 	int	cy_align;
 	register_t	eflags;
 	cy_addr	iobase;
+#ifdef SMP
+	int	need_unlock;
+#endif
 	int	val;
 
 	basecom = com_addr(com->unit & ~(CD1400_NO_OF_CHANNELS - 1));
@@ -2860,13 +2863,20 @@ cd_getreg(com, reg)
 	iobase = com->iobase;
 	eflags = read_eflags();
 	critical_enter();
-	if (eflags & PSL_I)
+#ifdef SMP
+	need_unlock = 0;
+	if (!mtx_owned(&com_mtx)) {
 		COM_LOCK();
+		need_unlock = 1;
+	}
+#endif
 	if (basecom->car != car)
 		cd_outb(iobase, CD1400_CAR, cy_align, basecom->car = car);
 	val = cd_inb(iobase, reg, cy_align);
-	if (eflags & PSL_I)
+#ifdef SMP
+	if (need_unlock)
 		COM_UNLOCK();
+#endif
 	critical_exit();
 	return (val);
 }
@@ -2882,6 +2892,9 @@ cd_setreg(com, reg, val)
 	int	cy_align;
 	register_t	eflags;
 	cy_addr	iobase;
+#ifdef SMP
+	int	need_unlock;
+#endif
 
 	basecom = com_addr(com->unit & ~(CD1400_NO_OF_CHANNELS - 1));
 	car = com->unit & CD1400_CAR_CHAN;
@@ -2889,13 +2902,20 @@ cd_setreg(com, reg, val)
 	iobase = com->iobase;
 	eflags = read_eflags();
 	critical_enter();
-	if (eflags & PSL_I)
+#ifdef SMP
+	need_unlock = 0;
+	if (!mtx_owned(&com_mtx)) {
 		COM_LOCK();
+		need_unlock = 1;
+	}
+#endif
 	if (basecom->car != car)
 		cd_outb(iobase, CD1400_CAR, cy_align, basecom->car = car);
 	cd_outb(iobase, reg, cy_align, val);
-	if (eflags & PSL_I)
+#ifdef SMP
+	if (need_unlock)
 		COM_UNLOCK();
+#endif
 	critical_exit();
 }
 
diff --git a/sys/i386/isa/cy.c b/sys/i386/isa/cy.c
index c8f2459..4bbedba 100644
--- a/sys/i386/isa/cy.c
+++ b/sys/i386/isa/cy.c
@@ -2852,6 +2852,9 @@ cd_getreg(com, reg)
 	int	cy_align;
 	register_t	eflags;
 	cy_addr	iobase;
+#ifdef SMP
+	int	need_unlock;
+#endif
 	int	val;
 
 	basecom = com_addr(com->unit & ~(CD1400_NO_OF_CHANNELS - 1));
@@ -2860,13 +2863,20 @@ cd_getreg(com, reg)
 	iobase = com->iobase;
 	eflags = read_eflags();
 	critical_enter();
-	if (eflags & PSL_I)
+#ifdef SMP
+	need_unlock = 0;
+	if (!mtx_owned(&com_mtx)) {
 		COM_LOCK();
+		need_unlock = 1;
+	}
+#endif
 	if (basecom->car != car)
 		cd_outb(iobase, CD1400_CAR, cy_align, basecom->car = car);
 	val = cd_inb(iobase, reg, cy_align);
-	if (eflags & PSL_I)
+#ifdef SMP
+	if (need_unlock)
 		COM_UNLOCK();
+#endif
 	critical_exit();
 	return (val);
 }
@@ -2882,6 +2892,9 @@ cd_setreg(com, reg, val)
 	int	cy_align;
 	register_t	eflags;
 	cy_addr	iobase;
+#ifdef SMP
+	int	need_unlock;
+#endif
 
 	basecom = com_addr(com->unit & ~(CD1400_NO_OF_CHANNELS - 1));
 	car = com->unit & CD1400_CAR_CHAN;
@@ -2889,13 +2902,20 @@ cd_setreg(com, reg, val)
 	iobase = com->iobase;
 	eflags = read_eflags();
 	critical_enter();
-	if (eflags & PSL_I)
+#ifdef SMP
+	need_unlock = 0;
+	if (!mtx_owned(&com_mtx)) {
 		COM_LOCK();
+		need_unlock = 1;
+	}
+#endif
 	if (basecom->car != car)
 		cd_outb(iobase, CD1400_CAR, cy_align, basecom->car = car);
 	cd_outb(iobase, reg, cy_align, val);
-	if (eflags & PSL_I)
+#ifdef SMP
+	if (need_unlock)
 		COM_UNLOCK();
+#endif
 	critical_exit();
 }