[ANNOUNCE] v5.2.21-rt14

[Sebastian Andrzej Siewior]

Dear RT folks!

I'm pleased to announce the v5.2.21-rt14 patch set. 

Changes since v5.2.21-rt13:

  - printk. The "emergency loglevel" was used to determine which
    messages are printed directly on the console (if atomic write is
    available (8250 only right now)). By default messages with the log
    level KERN_WARNING (and less) were printed directly.
    As part of the current printk rework it has been decided that only
    messages which lead to system failure like BUG(), panic() should use
    the direct interface. Patch by John Ogness.

  - Cherry pick a X86-FPU patch from upstream to avoid a miss
    compilation with gcc-9.

  - Make the spin_lock() section also part of a rcu read section on RT.

  - PowerPC on 32bit did not compile due to a missing function since the
    softirq rework. It also did not boot due to a bug in the
    lazy-preempt code. It compiles and it has been verified in qemu on a
    book-E target (due to lack of real hardware) that it boots again.

  - RT did not compile if CONFIG_HOTPLUG_CPU was not defined. Reported
    by Dick Hollenbeck.

Known issues
     - None

The delta patch against v5.2.21-rt13 is appended below and can be found here:
 
     https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.2/incr/patch-5.2.21-rt13-rt14.patch.xz

You can get this release via the git tree at:

    git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v5.2.21-rt14

The RT patch against v5.2.21 can be found here:

    https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.2/older/patch-5.2.21-rt14.patch.xz

The split quilt queue is available at:

    https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.2/older/patches-5.2.21-rt14.tar.xz

Sebastian

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index d37b373104502..004944258387b 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -893,10 +893,10 @@ user_exc_return:		/* r10 contains MSR_KERNEL here */
 	bne	restore_kuap
 	andi.	r8,r8,_TIF_NEED_RESCHED
 	bne+	1f
-	lwz	r0,TI_PREEMPT_LAZY(r9)
+	lwz	r0,TI_PREEMPT_LAZY(r2)
 	cmpwi	0,r0,0          /* if non-zero, just restore regs and return */
 	bne	restore_kuap
-	lwz	r0,TI_FLAGS(r9)
+	lwz	r0,TI_FLAGS(r2)
 	andi.	r0,r0,_TIF_NEED_RESCHED_LAZY
 	beq+	restore_kuap
 1:
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 4c95c365058aa..44c48e34d7994 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -509,7 +509,7 @@ static inline void __fpu_invalidate_fpregs_state(struct fpu *fpu)
 
 static inline int fpregs_state_valid(struct fpu *fpu, unsigned int cpu)
 {
-	return fpu == this_cpu_read_stable(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu;
+	return fpu == this_cpu_read(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu;
 }
 
 /*
diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index d559e3a0379c2..7653dd58b4b21 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -100,9 +100,9 @@
 				   (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)))
 #ifdef CONFIG_PREEMPT_RT_FULL
 
-#define softirq_count()		((long)get_current()->softirq_count)
+#define softirq_count()		(current->softirq_count)
 #define in_softirq()		(softirq_count())
-#define in_serving_softirq()	(get_current()->softirq_count & SOFTIRQ_OFFSET)
+#define in_serving_softirq()	(current->softirq_count & SOFTIRQ_OFFSET)
 
 #else
 
diff --git a/kernel/cpu.c b/kernel/cpu.c
index e1bf3c698a321..5bfd13a5cc49d 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -877,7 +877,9 @@ static int take_cpu_down(void *_param)
 	return 0;
 }
 
+#ifdef CONFIG_PREEMPT_RT_BASE
 struct task_struct *takedown_cpu_task;
+#endif
 
 static int takedown_cpu(unsigned int cpu)
 {
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index bb5c09c49c504..ba4b151bf4517 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1143,6 +1143,7 @@ void __sched rt_spin_lock_slowunlock(struct rt_mutex *lock)
 void __lockfunc rt_spin_lock(spinlock_t *lock)
 {
 	sleeping_lock_inc();
+	rcu_read_lock();
 	migrate_disable();
 	spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 	rt_spin_lock_fastlock(&lock->lock, rt_spin_lock_slowlock);
@@ -1158,6 +1159,7 @@ void __lockfunc __rt_spin_lock(struct rt_mutex *lock)
 void __lockfunc rt_spin_lock_nested(spinlock_t *lock, int subclass)
 {
 	sleeping_lock_inc();
+	rcu_read_lock();
 	migrate_disable();
 	spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
 	rt_spin_lock_fastlock(&lock->lock, rt_spin_lock_slowlock);
@@ -1171,6 +1173,7 @@ void __lockfunc rt_spin_unlock(spinlock_t *lock)
 	spin_release(&lock->dep_map, 1, _RET_IP_);
 	rt_spin_lock_fastunlock(&lock->lock, rt_spin_lock_slowunlock);
 	migrate_enable();
+	rcu_read_unlock();
 	sleeping_lock_dec();
 }
 EXPORT_SYMBOL(rt_spin_unlock);
@@ -1202,6 +1205,7 @@ int __lockfunc rt_spin_trylock(spinlock_t *lock)
 	ret = __rt_mutex_trylock(&lock->lock);
 	if (ret) {
 		spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
+		rcu_read_lock();
 	} else {
 		migrate_enable();
 		sleeping_lock_dec();
@@ -1218,6 +1222,7 @@ int __lockfunc rt_spin_trylock_bh(spinlock_t *lock)
 	ret = __rt_mutex_trylock(&lock->lock);
 	if (ret) {
 		sleeping_lock_inc();
+		rcu_read_lock();
 		migrate_disable();
 		spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
 	} else
@@ -1234,6 +1239,7 @@ int __lockfunc rt_spin_trylock_irqsave(spinlock_t *lock, unsigned long *flags)
 	ret = __rt_mutex_trylock(&lock->lock);
 	if (ret) {
 		sleeping_lock_inc();
+		rcu_read_lock();
 		migrate_disable();
 		spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
 	}
diff --git a/kernel/locking/rwlock-rt.c b/kernel/locking/rwlock-rt.c
index c3b91205161cc..0ae8c62ea8320 100644
--- a/kernel/locking/rwlock-rt.c
+++ b/kernel/locking/rwlock-rt.c
@@ -310,6 +310,7 @@ int __lockfunc rt_read_trylock(rwlock_t *rwlock)
 	ret = do_read_rt_trylock(rwlock);
 	if (ret) {
 		rwlock_acquire_read(&rwlock->dep_map, 0, 1, _RET_IP_);
+		rcu_read_lock();
 	} else {
 		migrate_enable();
 		sleeping_lock_dec();
@@ -327,6 +328,7 @@ int __lockfunc rt_write_trylock(rwlock_t *rwlock)
 	ret = do_write_rt_trylock(rwlock);
 	if (ret) {
 		rwlock_acquire(&rwlock->dep_map, 0, 1, _RET_IP_);
+		rcu_read_lock();
 	} else {
 		migrate_enable();
 		sleeping_lock_dec();
@@ -338,6 +340,7 @@ EXPORT_SYMBOL(rt_write_trylock);
 void __lockfunc rt_read_lock(rwlock_t *rwlock)
 {
 	sleeping_lock_inc();
+	rcu_read_lock();
 	migrate_disable();
 	rwlock_acquire_read(&rwlock->dep_map, 0, 0, _RET_IP_);
 	do_read_rt_lock(rwlock);
@@ -347,6 +350,7 @@ EXPORT_SYMBOL(rt_read_lock);
 void __lockfunc rt_write_lock(rwlock_t *rwlock)
 {
 	sleeping_lock_inc();
+	rcu_read_lock();
 	migrate_disable();
 	rwlock_acquire(&rwlock->dep_map, 0, 0, _RET_IP_);
 	do_write_rt_lock(rwlock);
@@ -358,6 +362,7 @@ void __lockfunc rt_read_unlock(rwlock_t *rwlock)
 	rwlock_release(&rwlock->dep_map, 1, _RET_IP_);
 	do_read_rt_unlock(rwlock);
 	migrate_enable();
+	rcu_read_unlock();
 	sleeping_lock_dec();
 }
 EXPORT_SYMBOL(rt_read_unlock);
@@ -367,6 +372,7 @@ void __lockfunc rt_write_unlock(rwlock_t *rwlock)
 	rwlock_release(&rwlock->dep_map, 1, _RET_IP_);
 	do_write_rt_unlock(rwlock);
 	migrate_enable();
+	rcu_read_unlock();
 	sleeping_lock_dec();
 }
 EXPORT_SYMBOL(rt_write_unlock);
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 9d9523431178b..2b4616fd4fd4b 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1767,15 +1767,8 @@ static void call_console_drivers(u64 seq, const char *ext_text, size_t ext_len,
 			con->wrote_history = 1;
 			con->printk_seq = seq - 1;
 		}
-		if (con->write_atomic && level < emergency_console_loglevel &&
-		    facility == 0) {
-			/* skip emergency messages, already printed */
-			if (con->printk_seq < seq)
-				con->printk_seq = seq;
-			continue;
-		}
 		if (con->flags & CON_BOOT && facility == 0) {
-			/* skip emergency messages, already printed */
+			/* skip boot messages, already printed */
 			if (con->printk_seq < seq)
 				con->printk_seq = seq;
 			continue;
@@ -3161,7 +3154,7 @@ static bool console_can_emergency(int level)
 	for_each_console(con) {
 		if (!(con->flags & CON_ENABLED))
 			continue;
-		if (con->write_atomic && level < emergency_console_loglevel)
+		if (con->write_atomic && oops_in_progress)
 			return true;
 		if (con->write && (con->flags & CON_BOOT))
 			return true;
@@ -3177,7 +3170,7 @@ static void call_emergency_console_drivers(int level, const char *text,
 	for_each_console(con) {
 		if (!(con->flags & CON_ENABLED))
 			continue;
-		if (con->write_atomic && level < emergency_console_loglevel) {
+		if (con->write_atomic && oops_in_progress) {
 			con->write_atomic(con, text, text_len);
 			continue;
 		}
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 6383ade320f23..ef9621815f37e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7384,9 +7384,11 @@ void migrate_enable(void)
 
 	p->migrate_disable = 0;
 	rq->nr_pinned--;
+#ifdef CONFIG_HOTPLUG_CPU
 	if (rq->nr_pinned == 0 && unlikely(!cpu_active(cpu)) &&
 	    takedown_cpu_task)
 		wake_up_process(takedown_cpu_task);
+#endif
 
 	if (!p->migrate_disable_scheduled)
 		goto out;
diff --git a/localversion-rt b/localversion-rt
index 9f7d0bdbffb18..08b3e75841adc 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt13
+-rt14