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@xxxxxxxxxxx> 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@xxxxxxxxxxx> --- 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
