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Subject[ANNOUNCE] 4.14.87-rt49

Dear RT Folks,

I'm pleased to announce the 4.14.87-rt49 stable release.

Sorry for taking so long, I've just been swamped (like everyone else)

*** PLEASE NOTE ***

This release is **NOT** just an update to the new stable 4.14.87 version
as there was a small RT specific change that has been made.

I had to make an update to handle a backport of adding
preempt_disable() around the console_unlock() code. That patch is below.

You can get this release via the git tree at:

git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git

branch: v4.14-rt
Head SHA1: c3fb62599cb0bf9ea0223433ccf7c0c37056c392


Or to build 4.14.87-rt49 directly, the following patches should be applied:

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

http://www.kernel.org/pub/linux/kernel/v4.x/patch-4.14.87.xz

http://www.kernel.org/pub/linux/kernel/projects/rt/4.14/patch-4.14.87-rt49.patch.xz




Enjoy,

-- Steve


From 0ab3459b0a8b8d19054aa813611c8dc22ce04af8 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Date: Fri, 14 Dec 2018 21:36:55 -0500
Subject: [PATCH] printk: Do not disable preemption when calling consoles in RT

console_unlock() may call consoles that call spin_lock(), where spin_lock is
a mutex in PREEMPT_RT. Although mainline may be worried about preempted
holders of the console lock from preventing printk() output, the RT kernel
does not.

Use migrate_disable() to disable preemption when !RT, but we really don't
care if the task stays on the CPU or not for RT. It just has to be able to
schedule.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/printk/printk.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 8a7c4f79fca0..029ae3caa80e 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1811,7 +1811,7 @@ asmlinkage int vprintk_emit(int facility, int level,
* console_sem which would prevent anyone from printing to
* console
*/
- preempt_disable();
+ migrate_disable();
/*
* Try to acquire and then immediately release the console
* semaphore. The release will print out buffers and wake up
@@ -1819,7 +1819,7 @@ asmlinkage int vprintk_emit(int facility, int level,
*/
if (may_trylock && console_trylock())
console_unlock();
- preempt_enable();
+ migrate_enable();
}

return printed_len;
--
2.19.2
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