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Date: Sun, 28 Oct 2012 23:33:14 +0100 (CET)
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
cc: linux-rt-users <linux-rt-users@...r.kernel.org>
Subject: [ANNOUNCE] 3.6.3-rt9
Dear RT Folks,
I'm pleased to announce the 3.6.3-rt9 release.
Changes since 3.6.3-rt8:
* hrtimer fix for interrupt stall case (Watanabe)
* Disable RCU_FAST_NO_HZ. Uses a timer_list timer in the guts of
the irq disable idle code. Needs some thought
* Netfilter RT workaround
* Adapt softirq_check_pending_idle() to the new softirq scheme
Fixes reports of bogus: softirq pending messages
* Add more debug to the softirq code to catch cases which use
__raise_softirq_irqsoff() in the wrong context
* Rework netif_rx_ni() to match the expectations of the new softirq
code.
The delta patch against 3.6.3-rt8 is appended below and can be found
here:
http://www.kernel.org/pub/linux/kernel/projects/rt/3.6/incr/patch-3.6.3-rt8-rt9.patch.xz
The RT patch against 3.6.3 can be found here:
http://www.kernel.org/pub/linux/kernel/projects/rt/3.6/patch-3.6.3-rt9.patch.xz
The split quilt queue is available at:
http://www.kernel.org/pub/linux/kernel/projects/rt/3.6/patches-3.6.3-rt9.tar.xz
Enjoy,
tglx
---------->
Index: linux-stable/include/linux/locallock.h
===================================================================
--- linux-stable.orig/include/linux/locallock.h
+++ linux-stable/include/linux/locallock.h
@@ -25,6 +25,9 @@ struct local_irq_lock {
DEFINE_PER_CPU(struct local_irq_lock, lvar) = { \
.lock = __SPIN_LOCK_UNLOCKED((lvar).lock) }
+#define DECLARE_LOCAL_IRQ_LOCK(lvar) \
+ DECLARE_PER_CPU(struct local_irq_lock, lvar)
+
#define local_irq_lock_init(lvar) \
do { \
int __cpu; \
@@ -220,6 +223,7 @@ static inline int __local_unlock_irqrest
#else /* PREEMPT_RT_BASE */
#define DEFINE_LOCAL_IRQ_LOCK(lvar) __typeof__(const int) lvar
+#define DECLARE_LOCAL_IRQ_LOCK(lvar) extern __typeof__(const int) lvar
static inline void local_irq_lock_init(int lvar) { }
Index: linux-stable/init/Kconfig
===================================================================
--- linux-stable.orig/init/Kconfig
+++ linux-stable/init/Kconfig
@@ -504,7 +504,7 @@ config RCU_FANOUT_EXACT
config RCU_FAST_NO_HZ
bool "Accelerate last non-dyntick-idle CPU's grace periods"
- depends on NO_HZ && SMP
+ depends on NO_HZ && SMP && !PREEMPT_RT_FULL
default n
help
This option causes RCU to attempt to accelerate grace periods
Index: linux-stable/kernel/hrtimer.c
===================================================================
--- linux-stable.orig/kernel/hrtimer.c
+++ linux-stable/kernel/hrtimer.c
@@ -1527,11 +1527,7 @@ retry:
if (expires_next.tv64 == KTIME_MAX ||
!tick_program_event(expires_next, 0)) {
cpu_base->hang_detected = 0;
-
- if (raise)
- raise_softirq_irqoff(HRTIMER_SOFTIRQ);
-
- return;
+ goto out;
}
/*
@@ -1575,6 +1571,9 @@ retry:
tick_program_event(expires_next, 1);
printk_once(KERN_WARNING "hrtimer: interrupt took %llu ns\n",
ktime_to_ns(delta));
+out:
+ if (raise)
+ raise_softirq_irqoff(HRTIMER_SOFTIRQ);
}
/*
Index: linux-stable/kernel/softirq.c
===================================================================
--- linux-stable.orig/kernel/softirq.c
+++ linux-stable/kernel/softirq.c
@@ -65,45 +65,75 @@ char *softirq_to_name[NR_SOFTIRQS] = {
#ifdef CONFIG_NO_HZ
# ifdef CONFIG_PREEMPT_RT_FULL
+
+struct softirq_runner {
+ struct task_struct *runner[NR_SOFTIRQS];
+};
+
+static DEFINE_PER_CPU(struct softirq_runner, softirq_runners);
+
+static inline void softirq_set_runner(unsigned int sirq)
+{
+ struct softirq_runner *sr = &__get_cpu_var(softirq_runners);
+
+ sr->runner[sirq] = current;
+}
+
+static inline void softirq_clr_runner(unsigned int sirq)
+{
+ struct softirq_runner *sr = &__get_cpu_var(softirq_runners);
+
+ sr->runner[sirq] = NULL;
+}
+
/*
- * On preempt-rt a softirq might be blocked on a lock. There might be
- * no other runnable task on this CPU because the lock owner runs on
- * some other CPU. So we have to go into idle with the pending bit
- * set. Therefor we need to check this otherwise we warn about false
- * positives which confuses users and defeats the whole purpose of
- * this test.
+ * On preempt-rt a softirq running context might be blocked on a
+ * lock. There might be no other runnable task on this CPU because the
+ * lock owner runs on some other CPU. So we have to go into idle with
+ * the pending bit set. Therefor we need to check this otherwise we
+ * warn about false positives which confuses users and defeats the
+ * whole purpose of this test.
*
* This code is called with interrupts disabled.
*/
void softirq_check_pending_idle(void)
{
static int rate_limit;
- u32 warnpending = 0, pending = local_softirq_pending();
+ struct softirq_runner *sr = &__get_cpu_var(softirq_runners);
+ u32 warnpending, pending = local_softirq_pending();
if (rate_limit >= 10)
return;
- if (pending) {
+ warnpending = pending;
+
+ while (pending) {
struct task_struct *tsk;
+ int i = __ffs(pending);
+
+ pending &= ~(1 << i);
- tsk = __get_cpu_var(ksoftirqd);
+ tsk = sr->runner[i];
/*
* The wakeup code in rtmutex.c wakes up the task
* _before_ it sets pi_blocked_on to NULL under
* tsk->pi_lock. So we need to check for both: state
* and pi_blocked_on.
*/
- raw_spin_lock(&tsk->pi_lock);
-
- if (!tsk->pi_blocked_on && !(tsk->state == TASK_RUNNING))
- warnpending = 1;
-
- raw_spin_unlock(&tsk->pi_lock);
+ if (tsk) {
+ raw_spin_lock(&tsk->pi_lock);
+ if (tsk->pi_blocked_on || tsk->state == TASK_RUNNING) {
+ /* Clear all bits pending in that task */
+ warnpending &= ~(tsk->softirqs_raised);
+ warnpending &= ~(1 << i);
+ }
+ raw_spin_unlock(&tsk->pi_lock);
+ }
}
if (warnpending) {
printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n",
- pending);
+ warnpending);
rate_limit++;
}
}
@@ -122,6 +152,10 @@ void softirq_check_pending_idle(void)
}
}
# endif
+
+#else /* !NO_HZ */
+static inline void softirq_set_runner(unsigned int sirq) { }
+static inline void softirq_clr_runner(unsigned int sirq) { }
#endif
/*
@@ -482,6 +516,7 @@ static void do_current_softirqs(int need
*/
lock_softirq(i);
local_irq_disable();
+ softirq_set_runner(i);
/*
* Check with the local_softirq_pending() bits,
* whether we need to process this still or if someone
@@ -492,6 +527,7 @@ static void do_current_softirqs(int need
set_softirq_pending(pending & ~mask);
do_single_softirq(i, need_rcu_bh_qs);
}
+ softirq_clr_runner(i);
unlock_softirq(i);
WARN_ON(current->softirq_nestcnt != 1);
}
@@ -582,7 +618,7 @@ void thread_do_softirq(void)
}
}
-void __raise_softirq_irqoff(unsigned int nr)
+static void do_raise_softirq_irqoff(unsigned int nr)
{
trace_softirq_raise(nr);
or_softirq_pending(1UL << nr);
@@ -599,12 +635,19 @@ void __raise_softirq_irqoff(unsigned int
__this_cpu_read(ksoftirqd)->softirqs_raised |= (1U << nr);
}
+void __raise_softirq_irqoff(unsigned int nr)
+{
+ do_raise_softirq_irqoff(nr);
+ if (WARN_ON_ONCE(!in_irq() && !current->softirq_nestcnt))
+ wakeup_softirqd();
+}
+
/*
* This function must run with irqs disabled!
*/
void raise_softirq_irqoff(unsigned int nr)
{
- __raise_softirq_irqoff(nr);
+ do_raise_softirq_irqoff(nr);
/*
* If we're in an hard interrupt we let irq return code deal
@@ -626,11 +669,6 @@ void raise_softirq_irqoff(unsigned int n
wakeup_softirqd();
}
-void do_raise_softirq_irqoff(unsigned int nr)
-{
- raise_softirq_irqoff(nr);
-}
-
static inline int ksoftirqd_softirq_pending(void)
{
return current->softirqs_raised;
Index: linux-stable/localversion-rt
===================================================================
--- linux-stable.orig/localversion-rt
+++ linux-stable/localversion-rt
@@ -1 +1 @@
--rt8
+-rt9
Index: linux-stable/net/core/dev.c
===================================================================
--- linux-stable.orig/net/core/dev.c
+++ linux-stable/net/core/dev.c
@@ -2993,11 +2993,9 @@ int netif_rx_ni(struct sk_buff *skb)
{
int err;
- migrate_disable();
+ local_bh_disable();
err = netif_rx(skb);
- if (local_softirq_pending())
- thread_do_softirq();
- migrate_enable();
+ local_bh_enable();
return err;
}
Index: linux-stable/include/linux/netfilter/x_tables.h
===================================================================
--- linux-stable.orig/include/linux/netfilter/x_tables.h
+++ linux-stable/include/linux/netfilter/x_tables.h
@@ -186,6 +186,7 @@ struct xt_counters_info {
#ifdef __KERNEL__
#include <linux/netdevice.h>
+#include <linux/locallock.h>
/**
* struct xt_action_param - parameters for matches/targets
@@ -466,6 +467,8 @@ extern void xt_free_table_info(struct xt
*/
DECLARE_PER_CPU(seqcount_t, xt_recseq);
+DECLARE_LOCAL_IRQ_LOCK(xt_write_lock);
+
/**
* xt_write_recseq_begin - start of a write section
*
@@ -480,6 +483,9 @@ static inline unsigned int xt_write_recs
{
unsigned int addend;
+ /* RT protection */
+ local_lock(xt_write_lock);
+
/*
* Low order bit of sequence is set if we already
* called xt_write_recseq_begin().
@@ -510,6 +516,7 @@ static inline void xt_write_recseq_end(u
/* this is kind of a write_seqcount_end(), but addend is 0 or 1 */
smp_wmb();
__this_cpu_add(xt_recseq.sequence, addend);
+ local_unlock(xt_write_lock);
}
/*
Index: linux-stable/net/netfilter/core.c
===================================================================
--- linux-stable.orig/net/netfilter/core.c
+++ linux-stable/net/netfilter/core.c
@@ -20,11 +20,17 @@
#include <linux/proc_fs.h>
#include <linux/mutex.h>
#include <linux/slab.h>
+#include <linux/locallock.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include "nf_internals.h"
+#ifdef CONFIG_PREEMPT_RT_BASE
+DEFINE_LOCAL_IRQ_LOCK(xt_write_lock);
+EXPORT_PER_CPU_SYMBOL(xt_write_lock);
+#endif
+
static DEFINE_MUTEX(afinfo_mutex);
const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly;
--
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