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-rw-r--r--debian/patches-rt/0004-sched-Provide-rt_mutex-specific-scheduler-helpers.patch128
1 files changed, 0 insertions, 128 deletions
diff --git a/debian/patches-rt/0004-sched-Provide-rt_mutex-specific-scheduler-helpers.patch b/debian/patches-rt/0004-sched-Provide-rt_mutex-specific-scheduler-helpers.patch
deleted file mode 100644
index f61a67ea3f..0000000000
--- a/debian/patches-rt/0004-sched-Provide-rt_mutex-specific-scheduler-helpers.patch
+++ /dev/null
@@ -1,128 +0,0 @@
-From: Peter Zijlstra <peterz@infradead.org>
-Date: Fri, 8 Sep 2023 18:22:51 +0200
-Subject: [PATCH 4/7] sched: Provide rt_mutex specific scheduler helpers
-Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz
-
-With PREEMPT_RT there is a rt_mutex recursion problem where
-sched_submit_work() can use an rtlock (aka spinlock_t). More
-specifically what happens is:
-
- mutex_lock() /* really rt_mutex */
- ...
- __rt_mutex_slowlock_locked()
- task_blocks_on_rt_mutex()
- // enqueue current task as waiter
- // do PI chain walk
- rt_mutex_slowlock_block()
- schedule()
- sched_submit_work()
- ...
- spin_lock() /* really rtlock */
- ...
- __rt_mutex_slowlock_locked()
- task_blocks_on_rt_mutex()
- // enqueue current task as waiter *AGAIN*
- // *CONFUSION*
-
-Fix this by making rt_mutex do the sched_submit_work() early, before
-it enqueues itself as a waiter -- before it even knows *if* it will
-wait.
-
-[[ basically Thomas' patch but with different naming and a few asserts
- added ]]
-
-Originally-by: Thomas Gleixner <tglx@linutronix.de>
-Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
-Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
-Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
-Link: https://lkml.kernel.org/r/20230908162254.999499-5-bigeasy@linutronix.de
----
- include/linux/sched.h | 3 +++
- include/linux/sched/rt.h | 4 ++++
- kernel/sched/core.c | 36 ++++++++++++++++++++++++++++++++----
- 3 files changed, 39 insertions(+), 4 deletions(-)
-
---- a/include/linux/sched.h
-+++ b/include/linux/sched.h
-@@ -911,6 +911,9 @@ struct task_struct {
- * ->sched_remote_wakeup gets used, so it can be in this word.
- */
- unsigned sched_remote_wakeup:1;
-+#ifdef CONFIG_RT_MUTEXES
-+ unsigned sched_rt_mutex:1;
-+#endif
-
- /* Bit to tell LSMs we're in execve(): */
- unsigned in_execve:1;
---- a/include/linux/sched/rt.h
-+++ b/include/linux/sched/rt.h
-@@ -30,6 +30,10 @@ static inline bool task_is_realtime(stru
- }
-
- #ifdef CONFIG_RT_MUTEXES
-+extern void rt_mutex_pre_schedule(void);
-+extern void rt_mutex_schedule(void);
-+extern void rt_mutex_post_schedule(void);
-+
- /*
- * Must hold either p->pi_lock or task_rq(p)->lock.
- */
---- a/kernel/sched/core.c
-+++ b/kernel/sched/core.c
-@@ -6724,9 +6724,6 @@ static inline void sched_submit_work(str
- static DEFINE_WAIT_OVERRIDE_MAP(sched_map, LD_WAIT_CONFIG);
- unsigned int task_flags;
-
-- if (task_is_running(tsk))
-- return;
--
- /*
- * Establish LD_WAIT_CONFIG context to ensure none of the code called
- * will use a blocking primitive -- which would lead to recursion.
-@@ -6784,7 +6781,12 @@ asmlinkage __visible void __sched schedu
- {
- struct task_struct *tsk = current;
-
-- sched_submit_work(tsk);
-+#ifdef CONFIG_RT_MUTEXES
-+ lockdep_assert(!tsk->sched_rt_mutex);
-+#endif
-+
-+ if (!task_is_running(tsk))
-+ sched_submit_work(tsk);
- __schedule_loop(SM_NONE);
- sched_update_worker(tsk);
- }
-@@ -7045,6 +7047,32 @@ static void __setscheduler_prio(struct t
-
- #ifdef CONFIG_RT_MUTEXES
-
-+/*
-+ * Would be more useful with typeof()/auto_type but they don't mix with
-+ * bit-fields. Since it's a local thing, use int. Keep the generic sounding
-+ * name such that if someone were to implement this function we get to compare
-+ * notes.
-+ */
-+#define fetch_and_set(x, v) ({ int _x = (x); (x) = (v); _x; })
-+
-+void rt_mutex_pre_schedule(void)
-+{
-+ lockdep_assert(!fetch_and_set(current->sched_rt_mutex, 1));
-+ sched_submit_work(current);
-+}
-+
-+void rt_mutex_schedule(void)
-+{
-+ lockdep_assert(current->sched_rt_mutex);
-+ __schedule_loop(SM_NONE);
-+}
-+
-+void rt_mutex_post_schedule(void)
-+{
-+ sched_update_worker(current);
-+ lockdep_assert(fetch_and_set(current->sched_rt_mutex, 0));
-+}
-+
- static inline int __rt_effective_prio(struct task_struct *pi_task, int prio)
- {
- if (pi_task)