[ANNOUNCE] 3.8.13.14-rt28

From: Steven Rostedt
Date: Fri Mar 07 2014 - 12:57:59 EST


Dear RT Folks,

I'm pleased to announce the 3.8.13.14-rt28 stable release.


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: v3.8-rt
Head SHA1: 4e356430b57e27543c552b19adf7cb0ce37197d3


Or to build 3.8.13.14-rt28 directly, the following patches should be applied:

http://www.kernel.org/pub/linux/kernel/v3.x/linux-3.8.tar.xz

http://www.kernel.org/pub/linux/kernel/v3.x/patch-3.8.13.xz

http://www.kernel.org/pub/linux/kernel/projects/rt/3.8/stable/patch-3.8.13.14.xz

http://www.kernel.org/pub/linux/kernel/projects/rt/3.8/patch-3.8.13.14-rt28.patch.xz



You can also build from 3.8.13.14-rt27 by applying the incremental patch:

http://www.kernel.org/pub/linux/kernel/projects/rt/3.8/incr/patch-3.8.13.14-rt27-rt28.patch.xz



Enjoy,

-- Steve


Changes from v3.8.13.14-rt27:

---

Nicholas Mc Guire (1):
net: ip_send_unicast_reply: add missing local serialization

Paul E. McKenney (1):
rcu: Eliminate softirq processing from rcutree

Sebastian Andrzej Siewior (3):
Revert "x86: Disable IST stacks for debug/int 3/stack fault for PREEMPT_RT"
kernel/hrtimer: be non-freezeable in cpu_chill()
arm/unwind: use a raw_spin_lock

Steven Rostedt (1):
rt: Make cpu_chill() use hrtimer instead of msleep()

Steven Rostedt (Red Hat) (1):
Linux 3.8.13.14-rt28

Tiejun Chen (1):
rcutree/rcu_bh_qs: disable irq while calling rcu_preempt_qs()

----
arch/arm/kernel/unwind.c | 14 ++--
arch/x86/include/asm/page_64_types.h | 21 ++----
arch/x86/kernel/cpu/common.c | 2 -
arch/x86/kernel/dumpstack_64.c | 4 --
include/linux/delay.h | 2 +-
kernel/hrtimer.c | 19 +++++
kernel/rcutree.c | 119 +++++++++++++++++++++++++++----
kernel/rcutree.h | 3 +-
kernel/rcutree_plugin.h | 133 ++++-------------------------------
localversion-rt | 2 +-
net/ipv4/ip_output.c | 9 ++-
11 files changed, 159 insertions(+), 169 deletions(-)
---------------------------
diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index 00df012..bbafc67 100644
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -87,7 +87,7 @@ extern const struct unwind_idx __start_unwind_idx[];
static const struct unwind_idx *__origin_unwind_idx;
extern const struct unwind_idx __stop_unwind_idx[];

-static DEFINE_SPINLOCK(unwind_lock);
+static DEFINE_RAW_SPINLOCK(unwind_lock);
static LIST_HEAD(unwind_tables);

/* Convert a prel31 symbol to an absolute address */
@@ -195,7 +195,7 @@ static const struct unwind_idx *unwind_find_idx(unsigned long addr)
/* module unwind tables */
struct unwind_table *table;

- spin_lock_irqsave(&unwind_lock, flags);
+ raw_spin_lock_irqsave(&unwind_lock, flags);
list_for_each_entry(table, &unwind_tables, list) {
if (addr >= table->begin_addr &&
addr < table->end_addr) {
@@ -207,7 +207,7 @@ static const struct unwind_idx *unwind_find_idx(unsigned long addr)
break;
}
}
- spin_unlock_irqrestore(&unwind_lock, flags);
+ raw_spin_unlock_irqrestore(&unwind_lock, flags);
}

pr_debug("%s: idx = %p\n", __func__, idx);
@@ -469,9 +469,9 @@ struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
tab->begin_addr = text_addr;
tab->end_addr = text_addr + text_size;

- spin_lock_irqsave(&unwind_lock, flags);
+ raw_spin_lock_irqsave(&unwind_lock, flags);
list_add_tail(&tab->list, &unwind_tables);
- spin_unlock_irqrestore(&unwind_lock, flags);
+ raw_spin_unlock_irqrestore(&unwind_lock, flags);

return tab;
}
@@ -483,9 +483,9 @@ void unwind_table_del(struct unwind_table *tab)
if (!tab)
return;

- spin_lock_irqsave(&unwind_lock, flags);
+ raw_spin_lock_irqsave(&unwind_lock, flags);
list_del(&tab->list);
- spin_unlock_irqrestore(&unwind_lock, flags);
+ raw_spin_unlock_irqrestore(&unwind_lock, flags);

kfree(tab);
}
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 65b85f4..320f7bb 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -14,21 +14,12 @@
#define IRQ_STACK_ORDER 2
#define IRQ_STACK_SIZE (PAGE_SIZE << IRQ_STACK_ORDER)

-#ifdef CONFIG_PREEMPT_RT_FULL
-# define STACKFAULT_STACK 0
-# define DOUBLEFAULT_STACK 1
-# define NMI_STACK 2
-# define DEBUG_STACK 0
-# define MCE_STACK 3
-# define N_EXCEPTION_STACKS 3 /* hw limit: 7 */
-#else
-# define STACKFAULT_STACK 1
-# define DOUBLEFAULT_STACK 2
-# define NMI_STACK 3
-# define DEBUG_STACK 4
-# define MCE_STACK 5
-# define N_EXCEPTION_STACKS 5 /* hw limit: 7 */
-#endif
+#define STACKFAULT_STACK 1
+#define DOUBLEFAULT_STACK 2
+#define NMI_STACK 3
+#define DEBUG_STACK 4
+#define MCE_STACK 5
+#define N_EXCEPTION_STACKS 5 /* hw limit: 7 */

#define PUD_PAGE_SIZE (_AC(1, UL) << PUD_SHIFT)
#define PUD_PAGE_MASK (~(PUD_PAGE_SIZE-1))
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 2636e0f..9c3ab43 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1103,9 +1103,7 @@ DEFINE_PER_CPU(struct task_struct *, fpu_owner_task);
*/
static const unsigned int exception_stack_sizes[N_EXCEPTION_STACKS] = {
[0 ... N_EXCEPTION_STACKS - 1] = EXCEPTION_STKSZ,
-#if DEBUG_STACK > 0
[DEBUG_STACK - 1] = DEBUG_STKSZ
-#endif
};

static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index f16c07b..b653675 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -21,14 +21,10 @@
(N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)

static char x86_stack_ids[][8] = {
-#if DEBUG_STACK > 0
[ DEBUG_STACK-1 ] = "#DB",
-#endif
[ NMI_STACK-1 ] = "NMI",
[ DOUBLEFAULT_STACK-1 ] = "#DF",
-#if STACKFAULT_STACK > 0
[ STACKFAULT_STACK-1 ] = "#SS",
-#endif
[ MCE_STACK-1 ] = "#MC",
#if DEBUG_STKSZ > EXCEPTION_STKSZ
[ N_EXCEPTION_STACKS ...
diff --git a/include/linux/delay.h b/include/linux/delay.h
index e23a7c0..37caab3 100644
--- a/include/linux/delay.h
+++ b/include/linux/delay.h
@@ -53,7 +53,7 @@ static inline void ssleep(unsigned int seconds)
}

#ifdef CONFIG_PREEMPT_RT_FULL
-# define cpu_chill() msleep(1)
+extern void cpu_chill(void);
#else
# define cpu_chill() cpu_relax()
#endif
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index aa5eb4f..2e66fbb 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1852,6 +1852,25 @@ SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
return hrtimer_nanosleep(&tu, rmtp, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
}

+#ifdef CONFIG_PREEMPT_RT_FULL
+/*
+ * Sleep for 1 ms in hope whoever holds what we want will let it go.
+ */
+void cpu_chill(void)
+{
+ struct timespec tu = {
+ .tv_nsec = NSEC_PER_MSEC,
+ };
+ unsigned int freeze_flag = current->flags & PF_NOFREEZE;
+
+ current->flags |= PF_NOFREEZE;
+ hrtimer_nanosleep(&tu, NULL, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
+ if (!freeze_flag)
+ current->flags &= ~PF_NOFREEZE;
+}
+EXPORT_SYMBOL(cpu_chill);
+#endif
+
/*
* Functions related to boot-time initialization:
*/
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 7ec834d..6a34f87 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -53,6 +53,11 @@
#include <linux/delay.h>
#include <linux/stop_machine.h>
#include <linux/random.h>
+#include <linux/delay.h>
+#include <linux/gfp.h>
+#include <linux/oom.h>
+#include <linux/smpboot.h>
+#include "time/tick-internal.h"

#include "rcutree.h"
#include <trace/events/rcu.h>
@@ -127,8 +132,6 @@ EXPORT_SYMBOL_GPL(rcu_scheduler_active);
*/
static int rcu_scheduler_fully_active __read_mostly;

-#ifdef CONFIG_RCU_BOOST
-
/*
* Control variables for per-CPU and per-rcu_node kthreads. These
* handle all flavors of RCU.
@@ -138,8 +141,6 @@ DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
DEFINE_PER_CPU(char, rcu_cpu_has_work);

-#endif /* #ifdef CONFIG_RCU_BOOST */
-
static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu);
static void invoke_rcu_core(void);
static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp);
@@ -186,7 +187,12 @@ static void rcu_preempt_qs(int cpu);

void rcu_bh_qs(int cpu)
{
+ unsigned long flags;
+
+ /* Callers to this function, rcu_preempt_qs(), must disable irqs. */
+ local_irq_save(flags);
rcu_preempt_qs(cpu);
+ local_irq_restore(flags);
}
#else
void rcu_bh_qs(int cpu)
@@ -2043,16 +2049,14 @@ __rcu_process_callbacks(struct rcu_state *rsp)
/*
* Do RCU core processing for the current CPU.
*/
-static void rcu_process_callbacks(struct softirq_action *unused)
+static void rcu_process_callbacks(void)
{
struct rcu_state *rsp;

if (cpu_is_offline(smp_processor_id()))
return;
- trace_rcu_utilization("Start RCU core");
for_each_rcu_flavor(rsp)
__rcu_process_callbacks(rsp);
- trace_rcu_utilization("End RCU core");
}

/*
@@ -2066,17 +2070,105 @@ static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
{
if (unlikely(!ACCESS_ONCE(rcu_scheduler_fully_active)))
return;
- if (likely(!rsp->boost)) {
- rcu_do_batch(rsp, rdp);
- return;
- }
- invoke_rcu_callbacks_kthread();
+ rcu_do_batch(rsp, rdp);
}

+static void rcu_wake_cond(struct task_struct *t, int status)
+{
+ /*
+ * If the thread is yielding, only wake it when this
+ * is invoked from idle
+ */
+ if (t && (status != RCU_KTHREAD_YIELDING || is_idle_task(current)))
+ wake_up_process(t);
+}
+
+/*
+ * Wake up this CPU's rcuc kthread to do RCU core processing.
+ */
static void invoke_rcu_core(void)
{
- raise_softirq(RCU_SOFTIRQ);
+ unsigned long flags;
+ struct task_struct *t;
+
+ if (!cpu_online(smp_processor_id()))
+ return;
+ local_irq_save(flags);
+ __this_cpu_write(rcu_cpu_has_work, 1);
+ t = __this_cpu_read(rcu_cpu_kthread_task);
+ if (t != NULL && current != t)
+ rcu_wake_cond(t, __this_cpu_read(rcu_cpu_kthread_status));
+ local_irq_restore(flags);
+}
+
+static void rcu_cpu_kthread_park(unsigned int cpu)
+{
+ per_cpu(rcu_cpu_kthread_status, cpu) = RCU_KTHREAD_OFFCPU;
+}
+
+static int rcu_cpu_kthread_should_run(unsigned int cpu)
+{
+ return __this_cpu_read(rcu_cpu_has_work);
+}
+
+/*
+ * Per-CPU kernel thread that invokes RCU callbacks. This replaces the
+ * RCU softirq used in flavors and configurations of RCU that do not
+ * support RCU priority boosting.
+ */
+static void rcu_cpu_kthread(unsigned int cpu)
+{
+ unsigned int *statusp = &__get_cpu_var(rcu_cpu_kthread_status);
+ char work, *workp = &__get_cpu_var(rcu_cpu_has_work);
+ int spincnt;
+
+ for (spincnt = 0; spincnt < 10; spincnt++) {
+ trace_rcu_utilization("Start CPU kthread@rcu_wait");
+ local_bh_disable();
+ *statusp = RCU_KTHREAD_RUNNING;
+ this_cpu_inc(rcu_cpu_kthread_loops);
+ local_irq_disable();
+ work = *workp;
+ *workp = 0;
+ local_irq_enable();
+ if (work)
+ rcu_process_callbacks();
+ local_bh_enable();
+ if (*workp == 0) {
+ trace_rcu_utilization("End CPU kthread@rcu_wait");
+ *statusp = RCU_KTHREAD_WAITING;
+ return;
+ }
+ }
+ *statusp = RCU_KTHREAD_YIELDING;
+ trace_rcu_utilization("Start CPU kthread@rcu_yield");
+ schedule_timeout_interruptible(2);
+ trace_rcu_utilization("End CPU kthread@rcu_yield");
+ *statusp = RCU_KTHREAD_WAITING;
+}
+
+static struct smp_hotplug_thread rcu_cpu_thread_spec = {
+ .store = &rcu_cpu_kthread_task,
+ .thread_should_run = rcu_cpu_kthread_should_run,
+ .thread_fn = rcu_cpu_kthread,
+ .thread_comm = "rcuc/%u",
+ .setup = rcu_cpu_kthread_setup,
+ .park = rcu_cpu_kthread_park,
+};
+
+/*
+ * Spawn per-CPU RCU core processing kthreads.
+ */
+static int __init rcu_spawn_core_kthreads(void)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ per_cpu(rcu_cpu_has_work, cpu) = 0;
+ BUG_ON(smpboot_register_percpu_thread(&rcu_cpu_thread_spec));
+ return 0;
}
+early_initcall(rcu_spawn_core_kthreads);

/*
* Handle any core-RCU processing required by a call_rcu() invocation.
@@ -3082,7 +3174,6 @@ void __init rcu_init(void)
rcu_init_one(&rcu_bh_state, &rcu_bh_data);
__rcu_init_preempt();
rcu_init_nocb();
- open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);

/*
* We don't need protection against CPU-hotplug here because
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 5cfdff9..d67eaed 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -519,10 +519,9 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
static void __init __rcu_init_preempt(void);
static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
-static void invoke_rcu_callbacks_kthread(void);
static bool rcu_is_callbacks_kthread(void);
+static void rcu_cpu_kthread_setup(unsigned int cpu);
#ifdef CONFIG_RCU_BOOST
-static void rcu_preempt_do_callbacks(void);
static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
struct rcu_node *rnp);
#endif /* #ifdef CONFIG_RCU_BOOST */
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 778f138..a24ee9f 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -24,11 +24,6 @@
* Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
*/

-#include <linux/delay.h>
-#include <linux/gfp.h>
-#include <linux/oom.h>
-#include <linux/smpboot.h>
-
#define RCU_KTHREAD_PRIO 1

#ifdef CONFIG_RCU_BOOST
@@ -648,15 +643,6 @@ static void rcu_preempt_check_callbacks(int cpu)
t->rcu_read_unlock_special |= RCU_READ_UNLOCK_NEED_QS;
}

-#ifdef CONFIG_RCU_BOOST
-
-static void rcu_preempt_do_callbacks(void)
-{
- rcu_do_batch(&rcu_preempt_state, &__get_cpu_var(rcu_preempt_data));
-}
-
-#endif /* #ifdef CONFIG_RCU_BOOST */
-
/*
* Queue a preemptible-RCU callback for invocation after a grace period.
*/
@@ -1092,6 +1078,19 @@ static void __init __rcu_init_preempt(void)

#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */

+/*
+ * If boosting, set rcuc kthreads to realtime priority.
+ */
+static void rcu_cpu_kthread_setup(unsigned int cpu)
+{
+#ifdef CONFIG_RCU_BOOST
+ struct sched_param sp;
+
+ sp.sched_priority = RCU_KTHREAD_PRIO;
+ sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
+#endif /* #ifdef CONFIG_RCU_BOOST */
+}
+
#ifdef CONFIG_RCU_BOOST

#include "rtmutex_common.h"
@@ -1123,16 +1122,6 @@ static void rcu_initiate_boost_trace(struct rcu_node *rnp)

#endif /* #else #ifdef CONFIG_RCU_TRACE */

-static void rcu_wake_cond(struct task_struct *t, int status)
-{
- /*
- * If the thread is yielding, only wake it when this
- * is invoked from idle
- */
- if (status != RCU_KTHREAD_YIELDING || is_idle_task(current))
- wake_up_process(t);
-}
-
/*
* Carry out RCU priority boosting on the task indicated by ->exp_tasks
* or ->boost_tasks, advancing the pointer to the next task in the
@@ -1276,23 +1265,6 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
}

/*
- * Wake up the per-CPU kthread to invoke RCU callbacks.
- */
-static void invoke_rcu_callbacks_kthread(void)
-{
- unsigned long flags;
-
- local_irq_save(flags);
- __this_cpu_write(rcu_cpu_has_work, 1);
- if (__this_cpu_read(rcu_cpu_kthread_task) != NULL &&
- current != __this_cpu_read(rcu_cpu_kthread_task)) {
- rcu_wake_cond(__this_cpu_read(rcu_cpu_kthread_task),
- __this_cpu_read(rcu_cpu_kthread_status));
- }
- local_irq_restore(flags);
-}
-
-/*
* Is the current CPU running the RCU-callbacks kthread?
* Caller must have preemption disabled.
*/
@@ -1346,67 +1318,6 @@ static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
return 0;
}

-static void rcu_kthread_do_work(void)
-{
- rcu_do_batch(&rcu_sched_state, &__get_cpu_var(rcu_sched_data));
- rcu_do_batch(&rcu_bh_state, &__get_cpu_var(rcu_bh_data));
- rcu_preempt_do_callbacks();
-}
-
-static void rcu_cpu_kthread_setup(unsigned int cpu)
-{
- struct sched_param sp;
-
- sp.sched_priority = RCU_KTHREAD_PRIO;
- sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
-}
-
-static void rcu_cpu_kthread_park(unsigned int cpu)
-{
- per_cpu(rcu_cpu_kthread_status, cpu) = RCU_KTHREAD_OFFCPU;
-}
-
-static int rcu_cpu_kthread_should_run(unsigned int cpu)
-{
- return __get_cpu_var(rcu_cpu_has_work);
-}
-
-/*
- * Per-CPU kernel thread that invokes RCU callbacks. This replaces the
- * RCU softirq used in flavors and configurations of RCU that do not
- * support RCU priority boosting.
- */
-static void rcu_cpu_kthread(unsigned int cpu)
-{
- unsigned int *statusp = &__get_cpu_var(rcu_cpu_kthread_status);
- char work, *workp = &__get_cpu_var(rcu_cpu_has_work);
- int spincnt;
-
- for (spincnt = 0; spincnt < 10; spincnt++) {
- trace_rcu_utilization("Start CPU kthread@rcu_wait");
- local_bh_disable();
- *statusp = RCU_KTHREAD_RUNNING;
- this_cpu_inc(rcu_cpu_kthread_loops);
- local_irq_disable();
- work = *workp;
- *workp = 0;
- local_irq_enable();
- if (work)
- rcu_kthread_do_work();
- local_bh_enable();
- if (*workp == 0) {
- trace_rcu_utilization("End CPU kthread@rcu_wait");
- *statusp = RCU_KTHREAD_WAITING;
- return;
- }
- }
- *statusp = RCU_KTHREAD_YIELDING;
- trace_rcu_utilization("Start CPU kthread@rcu_yield");
- schedule_timeout_interruptible(2);
- trace_rcu_utilization("End CPU kthread@rcu_yield");
- *statusp = RCU_KTHREAD_WAITING;
-}
-
/*
* Set the per-rcu_node kthread's affinity to cover all CPUs that are
* served by the rcu_node in question. The CPU hotplug lock is still
@@ -1440,27 +1351,14 @@ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
free_cpumask_var(cm);
}

-static struct smp_hotplug_thread rcu_cpu_thread_spec = {
- .store = &rcu_cpu_kthread_task,
- .thread_should_run = rcu_cpu_kthread_should_run,
- .thread_fn = rcu_cpu_kthread,
- .thread_comm = "rcuc/%u",
- .setup = rcu_cpu_kthread_setup,
- .park = rcu_cpu_kthread_park,
-};
-
/*
* Spawn all kthreads -- called as soon as the scheduler is running.
*/
static int __init rcu_spawn_kthreads(void)
{
struct rcu_node *rnp;
- int cpu;

rcu_scheduler_fully_active = 1;
- for_each_possible_cpu(cpu)
- per_cpu(rcu_cpu_has_work, cpu) = 0;
- BUG_ON(smpboot_register_percpu_thread(&rcu_cpu_thread_spec));
rnp = rcu_get_root(rcu_state);
(void)rcu_spawn_one_boost_kthread(rcu_state, rnp);
if (NUM_RCU_NODES > 1) {
@@ -1488,11 +1386,6 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}

-static void invoke_rcu_callbacks_kthread(void)
-{
- WARN_ON_ONCE(1);
-}
-
static bool rcu_is_callbacks_kthread(void)
{
return false;
diff --git a/localversion-rt b/localversion-rt
index be1e37b..5a64c9c 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt27
+-rt28
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 90af992..6e75fb1 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -79,6 +79,7 @@
#include <linux/mroute.h>
#include <linux/netlink.h>
#include <linux/tcp.h>
+#include <linux/locallock.h>

int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
EXPORT_SYMBOL(sysctl_ip_default_ttl);
@@ -1471,6 +1472,9 @@ static DEFINE_PER_CPU(struct inet_sock, unicast_sock) = {
.uc_ttl = -1,
};

+/* serialize concurrent calls on the same CPU to ip_send_unicast_reply */
+static DEFINE_LOCAL_IRQ_LOCK(unicast_lock);
+
void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr,
__be32 saddr, const struct ip_reply_arg *arg,
unsigned int len)
@@ -1508,8 +1512,7 @@ void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr,
if (IS_ERR(rt))
return;

- get_cpu_light();
- inet = &__get_cpu_var(unicast_sock);
+ inet = &get_locked_var(unicast_lock, unicast_sock);

inet->tos = arg->tos;
sk = &inet->sk;
@@ -1533,7 +1536,7 @@ void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr,
ip_push_pending_frames(sk, &fl4);
}

- put_cpu_light();
+ put_locked_var(unicast_lock, unicast_sock);

ip_rt_put(rt);
}
--
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