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-rw-r--r--features/rt/softirq-Make-softirq-control-and-processing-RT-aware.patch266
1 files changed, 0 insertions, 266 deletions
diff --git a/features/rt/softirq-Make-softirq-control-and-processing-RT-aware.patch b/features/rt/softirq-Make-softirq-control-and-processing-RT-aware.patch
deleted file mode 100644
index d5463dab..00000000
--- a/features/rt/softirq-Make-softirq-control-and-processing-RT-aware.patch
+++ /dev/null
@@ -1,266 +0,0 @@
-From 02c3efe5d766cd7ed6f81c784981b76c91238a21 Mon Sep 17 00:00:00 2001
-From: Thomas Gleixner <tglx@linutronix.de>
-Date: Tue, 9 Mar 2021 09:55:56 +0100
-Subject: [PATCH 058/191] softirq: Make softirq control and processing RT aware
-
-Provide a local lock based serialization for soft interrupts on RT which
-allows the local_bh_disabled() sections and servicing soft interrupts to be
-preemptible.
-
-Provide the necessary inline helpers which allow to reuse the bulk of the
-softirq processing code.
-
-Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
-Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
-Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
----
- include/linux/bottom_half.h | 2 +-
- kernel/softirq.c | 188 ++++++++++++++++++++++++++++++++++--
- 2 files changed, 182 insertions(+), 8 deletions(-)
-
-diff --git a/include/linux/bottom_half.h b/include/linux/bottom_half.h
-index a19519f4241d..e4dd613a070e 100644
---- a/include/linux/bottom_half.h
-+++ b/include/linux/bottom_half.h
-@@ -4,7 +4,7 @@
-
- #include <linux/preempt.h>
-
--#ifdef CONFIG_TRACE_IRQFLAGS
-+#if defined(CONFIG_PREEMPT_RT) || defined(CONFIG_TRACE_IRQFLAGS)
- extern void __local_bh_disable_ip(unsigned long ip, unsigned int cnt);
- #else
- static __always_inline void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
-diff --git a/kernel/softirq.c b/kernel/softirq.c
-index 373c6bb84f39..54fd7cc97a4a 100644
---- a/kernel/softirq.c
-+++ b/kernel/softirq.c
-@@ -13,6 +13,7 @@
- #include <linux/kernel_stat.h>
- #include <linux/interrupt.h>
- #include <linux/init.h>
-+#include <linux/local_lock.h>
- #include <linux/mm.h>
- #include <linux/notifier.h>
- #include <linux/percpu.h>
-@@ -103,20 +104,189 @@ EXPORT_PER_CPU_SYMBOL_GPL(hardirq_context);
- #endif
-
- /*
-- * preempt_count and SOFTIRQ_OFFSET usage:
-- * - preempt_count is changed by SOFTIRQ_OFFSET on entering or leaving
-- * softirq processing.
-- * - preempt_count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET)
-+ * SOFTIRQ_OFFSET usage:
-+ *
-+ * On !RT kernels 'count' is the preempt counter, on RT kernels this applies
-+ * to a per CPU counter and to task::softirqs_disabled_cnt.
-+ *
-+ * - count is changed by SOFTIRQ_OFFSET on entering or leaving softirq
-+ * processing.
-+ *
-+ * - count is changed by SOFTIRQ_DISABLE_OFFSET (= 2 * SOFTIRQ_OFFSET)
- * on local_bh_disable or local_bh_enable.
-+ *
- * This lets us distinguish between whether we are currently processing
- * softirq and whether we just have bh disabled.
- */
-+#ifdef CONFIG_PREEMPT_RT
-
--#ifdef CONFIG_TRACE_IRQFLAGS
- /*
-- * This is for softirq.c-internal use, where hardirqs are disabled
-+ * RT accounts for BH disabled sections in task::softirqs_disabled_cnt and
-+ * also in per CPU softirq_ctrl::cnt. This is necessary to allow tasks in a
-+ * softirq disabled section to be preempted.
-+ *
-+ * The per task counter is used for softirq_count(), in_softirq() and
-+ * in_serving_softirqs() because these counts are only valid when the task
-+ * holding softirq_ctrl::lock is running.
-+ *
-+ * The per CPU counter prevents pointless wakeups of ksoftirqd in case that
-+ * the task which is in a softirq disabled section is preempted or blocks.
-+ */
-+struct softirq_ctrl {
-+ local_lock_t lock;
-+ int cnt;
-+};
-+
-+static DEFINE_PER_CPU(struct softirq_ctrl, softirq_ctrl) = {
-+ .lock = INIT_LOCAL_LOCK(softirq_ctrl.lock),
-+};
-+
-+void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
-+{
-+ unsigned long flags;
-+ int newcnt;
-+
-+ WARN_ON_ONCE(in_hardirq());
-+
-+ /* First entry of a task into a BH disabled section? */
-+ if (!current->softirq_disable_cnt) {
-+ if (preemptible()) {
-+ local_lock(&softirq_ctrl.lock);
-+ /* Required to meet the RCU bottomhalf requirements. */
-+ rcu_read_lock();
-+ } else {
-+ DEBUG_LOCKS_WARN_ON(this_cpu_read(softirq_ctrl.cnt));
-+ }
-+ }
-+
-+ /*
-+ * Track the per CPU softirq disabled state. On RT this is per CPU
-+ * state to allow preemption of bottom half disabled sections.
-+ */
-+ newcnt = __this_cpu_add_return(softirq_ctrl.cnt, cnt);
-+ /*
-+ * Reflect the result in the task state to prevent recursion on the
-+ * local lock and to make softirq_count() & al work.
-+ */
-+ current->softirq_disable_cnt = newcnt;
-+
-+ if (IS_ENABLED(CONFIG_TRACE_IRQFLAGS) && newcnt == cnt) {
-+ raw_local_irq_save(flags);
-+ lockdep_softirqs_off(ip);
-+ raw_local_irq_restore(flags);
-+ }
-+}
-+EXPORT_SYMBOL(__local_bh_disable_ip);
-+
-+static void __local_bh_enable(unsigned int cnt, bool unlock)
-+{
-+ unsigned long flags;
-+ int newcnt;
-+
-+ DEBUG_LOCKS_WARN_ON(current->softirq_disable_cnt !=
-+ this_cpu_read(softirq_ctrl.cnt));
-+
-+ if (IS_ENABLED(CONFIG_TRACE_IRQFLAGS) && softirq_count() == cnt) {
-+ raw_local_irq_save(flags);
-+ lockdep_softirqs_on(_RET_IP_);
-+ raw_local_irq_restore(flags);
-+ }
-+
-+ newcnt = __this_cpu_sub_return(softirq_ctrl.cnt, cnt);
-+ current->softirq_disable_cnt = newcnt;
-+
-+ if (!newcnt && unlock) {
-+ rcu_read_unlock();
-+ local_unlock(&softirq_ctrl.lock);
-+ }
-+}
-+
-+void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
-+{
-+ bool preempt_on = preemptible();
-+ unsigned long flags;
-+ u32 pending;
-+ int curcnt;
-+
-+ WARN_ON_ONCE(in_irq());
-+ lockdep_assert_irqs_enabled();
-+
-+ local_irq_save(flags);
-+ curcnt = __this_cpu_read(softirq_ctrl.cnt);
-+
-+ /*
-+ * If this is not reenabling soft interrupts, no point in trying to
-+ * run pending ones.
-+ */
-+ if (curcnt != cnt)
-+ goto out;
-+
-+ pending = local_softirq_pending();
-+ if (!pending || ksoftirqd_running(pending))
-+ goto out;
-+
-+ /*
-+ * If this was called from non preemptible context, wake up the
-+ * softirq daemon.
-+ */
-+ if (!preempt_on) {
-+ wakeup_softirqd();
-+ goto out;
-+ }
-+
-+ /*
-+ * Adjust softirq count to SOFTIRQ_OFFSET which makes
-+ * in_serving_softirq() become true.
-+ */
-+ cnt = SOFTIRQ_OFFSET;
-+ __local_bh_enable(cnt, false);
-+ __do_softirq();
-+
-+out:
-+ __local_bh_enable(cnt, preempt_on);
-+ local_irq_restore(flags);
-+}
-+EXPORT_SYMBOL(__local_bh_enable_ip);
-+
-+/*
-+ * Invoked from ksoftirqd_run() outside of the interrupt disabled section
-+ * to acquire the per CPU local lock for reentrancy protection.
-+ */
-+static inline void ksoftirqd_run_begin(void)
-+{
-+ __local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET);
-+ local_irq_disable();
-+}
-+
-+/* Counterpart to ksoftirqd_run_begin() */
-+static inline void ksoftirqd_run_end(void)
-+{
-+ __local_bh_enable(SOFTIRQ_OFFSET, true);
-+ WARN_ON_ONCE(in_interrupt());
-+ local_irq_enable();
-+}
-+
-+static inline void softirq_handle_begin(void) { }
-+static inline void softirq_handle_end(void) { }
-+
-+static inline bool should_wake_ksoftirqd(void)
-+{
-+ return !this_cpu_read(softirq_ctrl.cnt);
-+}
-+
-+static inline void invoke_softirq(void)
-+{
-+ if (should_wake_ksoftirqd())
-+ wakeup_softirqd();
-+}
-+
-+#else /* CONFIG_PREEMPT_RT */
-+
-+/*
-+ * This one is for softirq.c-internal use, where hardirqs are disabled
- * legitimately:
- */
-+#ifdef CONFIG_TRACE_IRQFLAGS
- void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
- {
- unsigned long flags;
-@@ -277,6 +447,8 @@ asmlinkage __visible void do_softirq(void)
- local_irq_restore(flags);
- }
-
-+#endif /* !CONFIG_PREEMPT_RT */
-+
- /*
- * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times,
- * but break the loop if need_resched() is set or after 2 ms.
-@@ -381,8 +553,10 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
- pending >>= softirq_bit;
- }
-
-- if (__this_cpu_read(ksoftirqd) == current)
-+ if (!IS_ENABLED(CONFIG_PREEMPT_RT) &&
-+ __this_cpu_read(ksoftirqd) == current)
- rcu_softirq_qs();
-+
- local_irq_disable();
-
- pending = local_softirq_pending();
---
-2.19.1
-
generated by cgit 1.2.3-korg (git 2.39.0) at 2024-05-06 10:12:01 +0000