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authorPaul E. McKenney <paulmck@kernel.org>2019-11-09 09:42:13 -0800
committerPaul E. McKenney <paulmck@kernel.org>2020-01-10 14:00:56 -0800
commit860c8802ace14c646864795e057349c9fb2d60ad (patch)
treecdad6ba3395a783053aae02a85b70aaca470cee9
parentc54a2744497db4b6887b9c905ef7aa0b3620c956 (diff)
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rcu: Use WRITE_ONCE() for assignments to ->pprev for hlist_nulls
Eric Dumazet supplied a KCSAN report of a bug that forces use of hlist_unhashed_lockless() from sk_unhashed(): ------------------------------------------------------------------------ BUG: KCSAN: data-race in inet_unhash / inet_unhash write to 0xffff8880a69a0170 of 8 bytes by interrupt on cpu 1: __hlist_nulls_del include/linux/list_nulls.h:88 [inline] hlist_nulls_del_init_rcu include/linux/rculist_nulls.h:36 [inline] __sk_nulls_del_node_init_rcu include/net/sock.h:676 [inline] inet_unhash+0x38f/0x4a0 net/ipv4/inet_hashtables.c:612 tcp_set_state+0xfa/0x3e0 net/ipv4/tcp.c:2249 tcp_done+0x93/0x1e0 net/ipv4/tcp.c:3854 tcp_write_err+0x7e/0xc0 net/ipv4/tcp_timer.c:56 tcp_retransmit_timer+0x9b8/0x16d0 net/ipv4/tcp_timer.c:479 tcp_write_timer_handler+0x42d/0x510 net/ipv4/tcp_timer.c:599 tcp_write_timer+0xd1/0xf0 net/ipv4/tcp_timer.c:619 call_timer_fn+0x5f/0x2f0 kernel/time/timer.c:1404 expire_timers kernel/time/timer.c:1449 [inline] __run_timers kernel/time/timer.c:1773 [inline] __run_timers kernel/time/timer.c:1740 [inline] run_timer_softirq+0xc0c/0xcd0 kernel/time/timer.c:1786 __do_softirq+0x115/0x33f kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0xbb/0xe0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0xe6/0x280 arch/x86/kernel/apic/apic.c:1137 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830 native_safe_halt+0xe/0x10 arch/x86/kernel/paravirt.c:71 arch_cpu_idle+0x1f/0x30 arch/x86/kernel/process.c:571 default_idle_call+0x1e/0x40 kernel/sched/idle.c:94 cpuidle_idle_call kernel/sched/idle.c:154 [inline] do_idle+0x1af/0x280 kernel/sched/idle.c:263 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:355 start_secondary+0x208/0x260 arch/x86/kernel/smpboot.c:264 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241 read to 0xffff8880a69a0170 of 8 bytes by interrupt on cpu 0: sk_unhashed include/net/sock.h:607 [inline] inet_unhash+0x3d/0x4a0 net/ipv4/inet_hashtables.c:592 tcp_set_state+0xfa/0x3e0 net/ipv4/tcp.c:2249 tcp_done+0x93/0x1e0 net/ipv4/tcp.c:3854 tcp_write_err+0x7e/0xc0 net/ipv4/tcp_timer.c:56 tcp_retransmit_timer+0x9b8/0x16d0 net/ipv4/tcp_timer.c:479 tcp_write_timer_handler+0x42d/0x510 net/ipv4/tcp_timer.c:599 tcp_write_timer+0xd1/0xf0 net/ipv4/tcp_timer.c:619 call_timer_fn+0x5f/0x2f0 kernel/time/timer.c:1404 expire_timers kernel/time/timer.c:1449 [inline] __run_timers kernel/time/timer.c:1773 [inline] __run_timers kernel/time/timer.c:1740 [inline] run_timer_softirq+0xc0c/0xcd0 kernel/time/timer.c:1786 __do_softirq+0x115/0x33f kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0xbb/0xe0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0xe6/0x280 arch/x86/kernel/apic/apic.c:1137 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830 native_safe_halt+0xe/0x10 arch/x86/kernel/paravirt.c:71 arch_cpu_idle+0x1f/0x30 arch/x86/kernel/process.c:571 default_idle_call+0x1e/0x40 kernel/sched/idle.c:94 cpuidle_idle_call kernel/sched/idle.c:154 [inline] do_idle+0x1af/0x280 kernel/sched/idle.c:263 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:355 rest_init+0xec/0xf6 init/main.c:452 arch_call_rest_init+0x17/0x37 start_kernel+0x838/0x85e init/main.c:786 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:490 x86_64_start_kernel+0x72/0x76 arch/x86/kernel/head64.c:471 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.0-rc6+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ------------------------------------------------------------------------ This commit therefore replaces C-language assignments with WRITE_ONCE() in include/linux/list_nulls.h and include/linux/rculist_nulls.h. Reported-by: Eric Dumazet <edumazet@google.com> # For KCSAN Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
-rw-r--r--include/linux/list_nulls.h8
-rw-r--r--include/linux/rculist_nulls.h8
2 files changed, 8 insertions, 8 deletions
diff --git a/include/linux/list_nulls.h b/include/linux/list_nulls.h
index 3ef96743db8d..1ecd35664e0d 100644
--- a/include/linux/list_nulls.h
+++ b/include/linux/list_nulls.h
@@ -72,10 +72,10 @@ static inline void hlist_nulls_add_head(struct hlist_nulls_node *n,
struct hlist_nulls_node *first = h->first;
n->next = first;
- n->pprev = &h->first;
+ WRITE_ONCE(n->pprev, &h->first);
h->first = n;
if (!is_a_nulls(first))
- first->pprev = &n->next;
+ WRITE_ONCE(first->pprev, &n->next);
}
static inline void __hlist_nulls_del(struct hlist_nulls_node *n)
@@ -85,13 +85,13 @@ static inline void __hlist_nulls_del(struct hlist_nulls_node *n)
WRITE_ONCE(*pprev, next);
if (!is_a_nulls(next))
- next->pprev = pprev;
+ WRITE_ONCE(next->pprev, pprev);
}
static inline void hlist_nulls_del(struct hlist_nulls_node *n)
{
__hlist_nulls_del(n);
- n->pprev = LIST_POISON2;
+ WRITE_ONCE(n->pprev, LIST_POISON2);
}
/**
diff --git a/include/linux/rculist_nulls.h b/include/linux/rculist_nulls.h
index bc8206a8f30e..517a06f36c7a 100644
--- a/include/linux/rculist_nulls.h
+++ b/include/linux/rculist_nulls.h
@@ -34,7 +34,7 @@ static inline void hlist_nulls_del_init_rcu(struct hlist_nulls_node *n)
{
if (!hlist_nulls_unhashed(n)) {
__hlist_nulls_del(n);
- n->pprev = NULL;
+ WRITE_ONCE(n->pprev, NULL);
}
}
@@ -66,7 +66,7 @@ static inline void hlist_nulls_del_init_rcu(struct hlist_nulls_node *n)
static inline void hlist_nulls_del_rcu(struct hlist_nulls_node *n)
{
__hlist_nulls_del(n);
- n->pprev = LIST_POISON2;
+ WRITE_ONCE(n->pprev, LIST_POISON2);
}
/**
@@ -94,10 +94,10 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
struct hlist_nulls_node *first = h->first;
n->next = first;
- n->pprev = &h->first;
+ WRITE_ONCE(n->pprev, &h->first);
rcu_assign_pointer(hlist_nulls_first_rcu(h), n);
if (!is_a_nulls(first))
- first->pprev = &n->next;
+ WRITE_ONCE(first->pprev, &n->next);
}
/**