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From f8ae916b4a177f6852fd37fea0ad9e0a09a866c5 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 13 Jul 2010 15:41:55 +0200
Subject: [PATCH] net: iptables: Fix xt_info locking
commit 5bbbedcfeec4fb13f514cabf4383b62c2e141f76 in tip.
xt_info locking is an open coded rw_lock which works fine in mainline,
but on RT it's racy. Replace it with a real rwlock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
include/linux/netfilter/x_tables.h | 34 +++++++++++++++++++++++++---------
net/netfilter/x_tables.c | 5 +++++
2 files changed, 30 insertions(+), 9 deletions(-)
diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index dcc03d7..ae2ef0f 100644
--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -464,7 +464,11 @@ extern void xt_free_table_info(struct xt_table_info *info);
* necessary for reading the counters.
*/
struct xt_info_lock {
+#ifndef CONFIG_PREEMPT_RT
spinlock_t lock;
+#else
+ rwlock_t lock;
+#endif
unsigned char readers;
};
DECLARE_PER_CPU(struct xt_info_lock, xt_info_locks);
@@ -491,11 +495,14 @@ static inline int xt_info_rdlock_bh(void)
preempt_disable_rt();
cpu = smp_processor_id();
lock = &per_cpu(xt_info_locks, cpu);
- if (likely(!lock->readers++)) {
- preempt_enable_rt();
- spin_lock(&lock->lock);
- } else
- preempt_enable_rt();
+
+#ifndef CONFIG_PREEMPT_RT
+ if (likely(!--lock->readers))
+ spin_unlock(&lock->lock);
+#else
+ preempt_enable_rt();
+ read_lock(&lock->lock);
+#endif
return cpu;
}
@@ -503,13 +510,14 @@ static inline void xt_info_rdunlock_bh(int cpu)
{
struct xt_info_lock *lock = &per_cpu(xt_info_locks, cpu);
- preempt_disable_rt();
-
+#ifndef CONFIG_PREEMPT_RT
if (likely(!--lock->readers)) {
preempt_enable_rt();
spin_unlock(&lock->lock);
- } else
- preempt_enable_rt();
+ }
+#else
+ read_unlock(&lock->lock);
+#endif
local_bh_enable();
}
@@ -521,12 +529,20 @@ static inline void xt_info_rdunlock_bh(int cpu)
*/
static inline void xt_info_wrlock(unsigned int cpu)
{
+#ifndef CONFIG_PREEMPT_RT
spin_lock(&per_cpu(xt_info_locks, cpu).lock);
+#else
+ write_lock(&per_cpu(xt_info_locks, cpu).lock);
+#endif
}
static inline void xt_info_wrunlock(unsigned int cpu)
{
+#ifndef CONFIG_PREEMPT_RT
spin_unlock(&per_cpu(xt_info_locks, cpu).lock);
+#else
+ write_unlock(&per_cpu(xt_info_locks, cpu).lock);
+#endif
}
/*
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 665f5be..da3955e 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -1244,7 +1244,12 @@ static int __init xt_init(void)
for_each_possible_cpu(i) {
struct xt_info_lock *lock = &per_cpu(xt_info_locks, i);
+
+#ifndef CONFIG_PREEMPT_RT
spin_lock_init(&lock->lock);
+#else
+ rwlock_init(&lock->lock);
+#endif
lock->readers = 0;
}
--
1.7.0.4
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