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-rw-r--r--debian/patches-rt/0104-posix-timers-Thread-posix-cpu-timers-on-rt.patch269
1 files changed, 269 insertions, 0 deletions
diff --git a/debian/patches-rt/0104-posix-timers-Thread-posix-cpu-timers-on-rt.patch b/debian/patches-rt/0104-posix-timers-Thread-posix-cpu-timers-on-rt.patch
new file mode 100644
index 000000000..36a78b986
--- /dev/null
+++ b/debian/patches-rt/0104-posix-timers-Thread-posix-cpu-timers-on-rt.patch
@@ -0,0 +1,269 @@
+From 59ac8673b0cb63baa55b3058ba0cb36ecb14a9d7 Mon Sep 17 00:00:00 2001
+From: John Stultz <johnstul@us.ibm.com>
+Date: Fri, 3 Jul 2009 08:29:58 -0500
+Subject: [PATCH 104/347] posix-timers: Thread posix-cpu-timers on -rt
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz
+
+posix-cpu-timer code takes non -rt safe locks in hard irq
+context. Move it to a thread.
+
+[ 3.0 fixes from Peter Zijlstra <peterz@infradead.org> ]
+
+Signed-off-by: John Stultz <johnstul@us.ibm.com>
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+---
+ include/linux/sched.h | 3 +
+ init/init_task.c | 7 ++
+ kernel/fork.c | 3 +
+ kernel/time/posix-cpu-timers.c | 154 ++++++++++++++++++++++++++++++++-
+ 4 files changed, 164 insertions(+), 3 deletions(-)
+
+diff --git a/include/linux/sched.h b/include/linux/sched.h
+index 56047f57ebc7..5369eb1fd456 100644
+--- a/include/linux/sched.h
++++ b/include/linux/sched.h
+@@ -832,6 +832,9 @@ struct task_struct {
+ #ifdef CONFIG_POSIX_TIMERS
+ struct task_cputime cputime_expires;
+ struct list_head cpu_timers[3];
++#ifdef CONFIG_PREEMPT_RT_BASE
++ struct task_struct *posix_timer_list;
++#endif
+ #endif
+
+ /* Process credentials: */
+diff --git a/init/init_task.c b/init/init_task.c
+index d71054b95528..634becebd713 100644
+--- a/init/init_task.c
++++ b/init/init_task.c
+@@ -50,6 +50,12 @@ static struct sighand_struct init_sighand = {
+ .signalfd_wqh = __WAIT_QUEUE_HEAD_INITIALIZER(init_sighand.signalfd_wqh),
+ };
+
++#if defined(CONFIG_POSIX_TIMERS) && defined(CONFIG_PREEMPT_RT_BASE)
++# define INIT_TIMER_LIST .posix_timer_list = NULL,
++#else
++# define INIT_TIMER_LIST
++#endif
++
+ /*
+ * Set up the first task table, touch at your own risk!. Base=0,
+ * limit=0x1fffff (=2MB)
+@@ -119,6 +125,7 @@ struct task_struct init_task
+ INIT_CPU_TIMERS(init_task)
+ .pi_lock = __RAW_SPIN_LOCK_UNLOCKED(init_task.pi_lock),
+ .timer_slack_ns = 50000, /* 50 usec default slack */
++ INIT_TIMER_LIST
+ .thread_pid = &init_struct_pid,
+ .thread_group = LIST_HEAD_INIT(init_task.thread_group),
+ .thread_node = LIST_HEAD_INIT(init_signals.thread_head),
+diff --git a/kernel/fork.c b/kernel/fork.c
+index a18d695259af..c27c196fd70e 100644
+--- a/kernel/fork.c
++++ b/kernel/fork.c
+@@ -1587,6 +1587,9 @@ static void rt_mutex_init_task(struct task_struct *p)
+ */
+ static void posix_cpu_timers_init(struct task_struct *tsk)
+ {
++#ifdef CONFIG_PREEMPT_RT_BASE
++ tsk->posix_timer_list = NULL;
++#endif
+ tsk->cputime_expires.prof_exp = 0;
+ tsk->cputime_expires.virt_exp = 0;
+ tsk->cputime_expires.sched_exp = 0;
+diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
+index bfaa44a80c03..2d29b269dc83 100644
+--- a/kernel/time/posix-cpu-timers.c
++++ b/kernel/time/posix-cpu-timers.c
+@@ -3,8 +3,10 @@
+ * Implement CPU time clocks for the POSIX clock interface.
+ */
+
++#include <uapi/linux/sched/types.h>
+ #include <linux/sched/signal.h>
+ #include <linux/sched/cputime.h>
++#include <linux/sched/rt.h>
+ #include <linux/posix-timers.h>
+ #include <linux/errno.h>
+ #include <linux/math64.h>
+@@ -15,6 +17,7 @@
+ #include <linux/workqueue.h>
+ #include <linux/compat.h>
+ #include <linux/sched/deadline.h>
++#include <linux/smpboot.h>
+
+ #include "posix-timers.h"
+
+@@ -1140,14 +1143,12 @@ static inline int fastpath_timer_check(struct task_struct *tsk)
+ * already updated our counts. We need to check if any timers fire now.
+ * Interrupts are disabled.
+ */
+-void run_posix_cpu_timers(struct task_struct *tsk)
++static void __run_posix_cpu_timers(struct task_struct *tsk)
+ {
+ LIST_HEAD(firing);
+ struct k_itimer *timer, *next;
+ unsigned long flags;
+
+- lockdep_assert_irqs_disabled();
+-
+ /*
+ * The fast path checks that there are no expired thread or thread
+ * group timers. If that's so, just return.
+@@ -1200,6 +1201,153 @@ void run_posix_cpu_timers(struct task_struct *tsk)
+ }
+ }
+
++#ifdef CONFIG_PREEMPT_RT_BASE
++#include <linux/kthread.h>
++#include <linux/cpu.h>
++DEFINE_PER_CPU(struct task_struct *, posix_timer_task);
++DEFINE_PER_CPU(struct task_struct *, posix_timer_tasklist);
++DEFINE_PER_CPU(bool, posix_timer_th_active);
++
++static void posix_cpu_kthread_fn(unsigned int cpu)
++{
++ struct task_struct *tsk = NULL;
++ struct task_struct *next = NULL;
++
++ BUG_ON(per_cpu(posix_timer_task, cpu) != current);
++
++ /* grab task list */
++ raw_local_irq_disable();
++ tsk = per_cpu(posix_timer_tasklist, cpu);
++ per_cpu(posix_timer_tasklist, cpu) = NULL;
++ raw_local_irq_enable();
++
++ /* its possible the list is empty, just return */
++ if (!tsk)
++ return;
++
++ /* Process task list */
++ while (1) {
++ /* save next */
++ next = tsk->posix_timer_list;
++
++ /* run the task timers, clear its ptr and
++ * unreference it
++ */
++ __run_posix_cpu_timers(tsk);
++ tsk->posix_timer_list = NULL;
++ put_task_struct(tsk);
++
++ /* check if this is the last on the list */
++ if (next == tsk)
++ break;
++ tsk = next;
++ }
++}
++
++static inline int __fastpath_timer_check(struct task_struct *tsk)
++{
++ /* tsk == current, ensure it is safe to use ->signal/sighand */
++ if (unlikely(tsk->exit_state))
++ return 0;
++
++ if (!task_cputime_zero(&tsk->cputime_expires))
++ return 1;
++
++ if (!task_cputime_zero(&tsk->signal->cputime_expires))
++ return 1;
++
++ return 0;
++}
++
++void run_posix_cpu_timers(struct task_struct *tsk)
++{
++ unsigned int cpu = smp_processor_id();
++ struct task_struct *tasklist;
++
++ BUG_ON(!irqs_disabled());
++
++ if (per_cpu(posix_timer_th_active, cpu) != true)
++ return;
++
++ /* get per-cpu references */
++ tasklist = per_cpu(posix_timer_tasklist, cpu);
++
++ /* check to see if we're already queued */
++ if (!tsk->posix_timer_list && __fastpath_timer_check(tsk)) {
++ get_task_struct(tsk);
++ if (tasklist) {
++ tsk->posix_timer_list = tasklist;
++ } else {
++ /*
++ * The list is terminated by a self-pointing
++ * task_struct
++ */
++ tsk->posix_timer_list = tsk;
++ }
++ per_cpu(posix_timer_tasklist, cpu) = tsk;
++
++ wake_up_process(per_cpu(posix_timer_task, cpu));
++ }
++}
++
++static int posix_cpu_kthread_should_run(unsigned int cpu)
++{
++ return __this_cpu_read(posix_timer_tasklist) != NULL;
++}
++
++static void posix_cpu_kthread_park(unsigned int cpu)
++{
++ this_cpu_write(posix_timer_th_active, false);
++}
++
++static void posix_cpu_kthread_unpark(unsigned int cpu)
++{
++ this_cpu_write(posix_timer_th_active, true);
++}
++
++static void posix_cpu_kthread_setup(unsigned int cpu)
++{
++ struct sched_param sp;
++
++ sp.sched_priority = MAX_RT_PRIO - 1;
++ sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
++ posix_cpu_kthread_unpark(cpu);
++}
++
++static struct smp_hotplug_thread posix_cpu_thread = {
++ .store = &posix_timer_task,
++ .thread_should_run = posix_cpu_kthread_should_run,
++ .thread_fn = posix_cpu_kthread_fn,
++ .thread_comm = "posixcputmr/%u",
++ .setup = posix_cpu_kthread_setup,
++ .park = posix_cpu_kthread_park,
++ .unpark = posix_cpu_kthread_unpark,
++};
++
++static int __init posix_cpu_thread_init(void)
++{
++ /* Start one for boot CPU. */
++ unsigned long cpu;
++ int ret;
++
++ /* init the per-cpu posix_timer_tasklets */
++ for_each_possible_cpu(cpu)
++ per_cpu(posix_timer_tasklist, cpu) = NULL;
++
++ ret = smpboot_register_percpu_thread(&posix_cpu_thread);
++ WARN_ON(ret);
++
++ return 0;
++}
++early_initcall(posix_cpu_thread_init);
++#else /* CONFIG_PREEMPT_RT_BASE */
++void run_posix_cpu_timers(struct task_struct *tsk)
++{
++ lockdep_assert_irqs_disabled();
++ __run_posix_cpu_timers(tsk);
++}
++#endif /* CONFIG_PREEMPT_RT_BASE */
++
+ /*
+ * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
+ * The tsk->sighand->siglock must be held by the caller.
+--
+2.36.1
+
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