[PATCH RT 0/3] Linux v4.14.320-rt152-rc1

[PATCH RT 0/3] Linux v4.14.320-rt152-rc1

[Luis Claudio R. Goncalves]

Dear RT Folks,

This is the RT stable review cycle of patch 4.14.320-rt152-rc1.

Please scream at me if I messed something up. Please test the patches
too.

The -rc release will be uploaded to kernel.org and will be deleted
when the final release is out. This is just a review release (or
release candidate).

The pre-releases will not be pushed to the git repository, only the
final release is.

If all goes well, this patch will be converted to the next main
release on 2023-08-15.

To build 4.14.320-rt152-rc1 directly, the following patches should be applied:

  https://www.kernel.org/pub/linux/kernel/v4.x/linux-4.14.tar.xz

  https://www.kernel.org/pub/linux/kernel/v4.x/patch-4.14.320.xz

  https://www.kernel.org/pub/linux/kernel/projects/rt/4.14/older/patch-4.14.320-rt152-rc1.patch.xz

Signing key fingerprint:

  9354 0649 9972 8D31 D464  D140 F394 A423 F8E6 7C26

All keys used for the above files and repositories can be found on the
following git repository:

   git://git.kernel.org/pub/scm/docs/kernel/pgpkeys.git

Enjoy!
Luis

Changes from v4.14.320-rt151:


Clark Williams (1):
  rt: PREEMPT_RT safety net for backported patches

Luis Claudio R. Goncalves (2):
  rt: timers: use CONFIG_PREEMPT_RT_FULL instead of CONFIG_PREEMPT_RT
  Linux 4.14.320-rt152-rc1

 kernel/Kconfig.preempt | 4 ++++
 kernel/time/timer.c    | 4 ++--
 localversion-rt        | 2 +-
 3 files changed, 7 insertions(+), 3 deletions(-)

-- 
2.41.0

[PATCH RT 1/3] rt: timers: use CONFIG_PREEMPT_RT_FULL instead of CONFIG_PREEMPT_RT

[Luis Claudio R. Goncalves]

v4.14.320-rt152-rc1 stable review patch.
If anyone has any objections, please let me know.

-----------


Commit 095ff4885a17 ("timers: Prepare support for PREEMPT_RT") had references
to CONFIG_PREEMPT_RT, that does not exist in v4.14-rt.

André Pribil reported that a tcdrain() call from userspace was spinning
forever due to an endless loop in del_timer_sync(). He was able to fix the
problem by Replacing CONFIG_PREEMPT_RT with CONFIG_PREEMPT_RT_FULL in that
code.

Reported-by: André Pribil <Andre.Pribil@hms-networks.com>
Fixes: 095ff4885a17 ("timers: Prepare support for PREEMPT_RT")
Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
---
 kernel/time/timer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index a3f229dc75ec..e1b5dfa260a4 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -198,7 +198,7 @@ EXPORT_SYMBOL(jiffies_64);
 struct timer_base {
 	raw_spinlock_t		lock;
 	struct timer_list	*running_timer;
-#ifdef CONFIG_PREEMPT_RT
+#ifdef CONFIG_PREEMPT_RT_FULL
 	spinlock_t		expiry_lock;
 	atomic_t		timer_waiters;
 #endif
@@ -1207,7 +1207,7 @@ int try_to_del_timer_sync(struct timer_list *timer)
 }
 EXPORT_SYMBOL(try_to_del_timer_sync);
 
-#ifdef CONFIG_PREEMPT_RT
+#ifdef CONFIG_PREEMPT_RT_FULL
 static __init void timer_base_init_expiry_lock(struct timer_base *base)
 {
 	spin_lock_init(&base->expiry_lock);
-- 
2.41.0

[PATCH RT 2/3] rt: PREEMPT_RT safety net for backported patches

[Luis Claudio R. Goncalves]

From: Clark Williams <clark.williams@gmail.com>

v4.14.320-rt152-rc1 stable review patch.
If anyone has any objections, please let me know.

-----------


[ commit 67821680a2b828aa405a2db5d7dbd812a3684fcf from v4.19-rt ]

While doing some 4.19-rt cleanup work, I stumbled across the fact that parts of
two backported patches were dependent on CONFIG_PREEMPT_RT, rather than
the CONFIG_PREEMPT_RT_FULL used in 4.19 and earlier RT series.  The commits
in the linux-stable-rt v4.19-rt branch are:

dad4c6a33bf4e mm: slub: Don't resize the location tracking cache on PREEMPT_RT
e626b6f873f2c net: Treat __napi_schedule_irqoff() as __napi_schedule() on PREEMPT_RT

Discussing this at the Stable RT maintainers meeting, Steven Rostedt suggested that
we automagically select CONFIG_PREEMPT_RT if CONFIG_PREEMPT_RT_FULL is on, giving
us a safety net for any subsequently backported patches. Here's my first cut at
that patch.

I suspect we'll need a similar patch for stable RT kernels < 4.19.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Clark Williams <williams@redhat.com>
Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
---
 kernel/Kconfig.preempt | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index 11dbe26a8279..97875b4eb569 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -6,6 +6,9 @@ config PREEMPT_RT_BASE
 	bool
 	select PREEMPT
 
+config PREEMPT_RT
+       bool
+
 config HAVE_PREEMPT_LAZY
 	bool
 
@@ -78,6 +81,7 @@ config PREEMPT_RT_FULL
 	depends on IRQ_FORCED_THREADING
 	select PREEMPT_RT_BASE
 	select PREEMPT_RCU
+	select PREEMPT_RT
 	help
 	  All and everything
 
-- 
2.41.0

[PATCH RT 3/3] Linux 4.14.320-rt152-rc1

[Luis Claudio R. Goncalves]

v4.14.320-rt152-rc1 stable review patch.
If anyone has any objections, please let me know.

-----------


Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
---
 localversion-rt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/localversion-rt b/localversion-rt
index 7c59c4689f8b..95561e32e8aa 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt151
+-rt152-rc1
-- 
2.41.0

Re: [PATCH RT 0/3] Linux v4.14.320-rt152-rc1

[Sebastian Andrzej Siewior]

On 2023-08-08 13:35:17 [-0300], Luis Claudio R. Goncalves wrote:
> Dear RT Folks,
> 
> This is the RT stable review cycle of patch 4.14.320-rt152-rc1.
> 
> Please scream at me if I messed something up. Please test the patches
> too.

Looks good, just a nitpick: If you add 2/3 you don't need 1/3.

Sebastian

Re: [PATCH RT 0/3] Linux v4.14.320-rt152-rc1

[Luis Claudio R. Goncalves]

On Wed, Aug 09, 2023 at 10:17:38AM +0200, Sebastian Andrzej Siewior wrote:
> On 2023-08-08 13:35:17 [-0300], Luis Claudio R. Goncalves wrote:
> > Dear RT Folks,
> > 
> > This is the RT stable review cycle of patch 4.14.320-rt152-rc1.
> > 
> > Please scream at me if I messed something up. Please test the patches
> > too.
> 
> Looks good, just a nitpick: If you add 2/3 you don't need 1/3.

Agreed. I just kept 1/3 because I wanted to both give credit to André Pribil
for reporting the problem and also highlight the symptom he observed.
Should I add that as a note on 2/3 and drop the first patch?

Thanks for reviewing the RC!
Luis

Re: [PATCH RT 0/3] Linux v4.14.320-rt152-rc1

[Sebastian Andrzej Siewior]

On 2023-08-09 10:50:59 [-0300], Luis Claudio R. Goncalves wrote:
> On Wed, Aug 09, 2023 at 10:17:38AM +0200, Sebastian Andrzej Siewior wrote:
> > Looks good, just a nitpick: If you add 2/3 you don't need 1/3.
> 
> Agreed. I just kept 1/3 because I wanted to both give credit to André Pribil
> for reporting the problem and also highlight the symptom he observed.
> Should I add that as a note on 2/3 and drop the first patch?

Sure. Instead of fixing that one incident (and there were of few of
those as far as I remember) it is more future proof to do what Steven
suggested.

> Thanks for reviewing the RC!
> Luis

Sebastian