From: "tip-bot2 for Eric Dumazet" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: syzbot <syzkaller@googlegroups.com>,
Eric Dumazet <edumazet@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org
Subject: [tip: timers/core] hrtimer: Annotate lockless access to timer->state
Date: Wed, 06 Nov 2019 22:24:19 -0000 [thread overview]
Message-ID: <157307905904.29376.8711513726869840596.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20191106174804.74723-1-edumazet@google.com>
The following commit has been merged into the timers/core branch of tip:
Commit-ID: 56144737e67329c9aaed15f942d46a6302e2e3d8
Gitweb: https://git.kernel.org/tip/56144737e67329c9aaed15f942d46a6302e2e3d8
Author: Eric Dumazet <edumazet@google.com>
AuthorDate: Wed, 06 Nov 2019 09:48:04 -08:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 06 Nov 2019 23:18:31 +01:00
hrtimer: Annotate lockless access to timer->state
syzbot reported various data-race caused by hrtimer_is_queued() reading
timer->state. A READ_ONCE() is required there to silence the warning.
Also add the corresponding WRITE_ONCE() when timer->state is set.
In remove_hrtimer() the hrtimer_is_queued() helper is open coded to avoid
loading timer->state twice.
KCSAN reported these cases:
BUG: KCSAN: data-race in __remove_hrtimer / tcp_pacing_check
write to 0xffff8880b2a7d388 of 1 bytes by interrupt on cpu 0:
__remove_hrtimer+0x52/0x130 kernel/time/hrtimer.c:991
__run_hrtimer kernel/time/hrtimer.c:1496 [inline]
__hrtimer_run_queues+0x250/0x600 kernel/time/hrtimer.c:1576
hrtimer_run_softirq+0x10e/0x150 kernel/time/hrtimer.c:1593
__do_softirq+0x115/0x33f kernel/softirq.c:292
run_ksoftirqd+0x46/0x60 kernel/softirq.c:603
smpboot_thread_fn+0x37d/0x4a0 kernel/smpboot.c:165
kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352
read to 0xffff8880b2a7d388 of 1 bytes by task 24652 on cpu 1:
tcp_pacing_check net/ipv4/tcp_output.c:2235 [inline]
tcp_pacing_check+0xba/0x130 net/ipv4/tcp_output.c:2225
tcp_xmit_retransmit_queue+0x32c/0x5a0 net/ipv4/tcp_output.c:3044
tcp_xmit_recovery+0x7c/0x120 net/ipv4/tcp_input.c:3558
tcp_ack+0x17b6/0x3170 net/ipv4/tcp_input.c:3717
tcp_rcv_established+0x37e/0xf50 net/ipv4/tcp_input.c:5696
tcp_v4_do_rcv+0x381/0x4e0 net/ipv4/tcp_ipv4.c:1561
sk_backlog_rcv include/net/sock.h:945 [inline]
__release_sock+0x135/0x1e0 net/core/sock.c:2435
release_sock+0x61/0x160 net/core/sock.c:2951
sk_stream_wait_memory+0x3d7/0x7c0 net/core/stream.c:145
tcp_sendmsg_locked+0xb47/0x1f30 net/ipv4/tcp.c:1393
tcp_sendmsg+0x39/0x60 net/ipv4/tcp.c:1434
inet_sendmsg+0x6d/0x90 net/ipv4/af_inet.c:807
sock_sendmsg_nosec net/socket.c:637 [inline]
sock_sendmsg+0x9f/0xc0 net/socket.c:657
BUG: KCSAN: data-race in __remove_hrtimer / __tcp_ack_snd_check
write to 0xffff8880a3a65588 of 1 bytes by interrupt on cpu 0:
__remove_hrtimer+0x52/0x130 kernel/time/hrtimer.c:991
__run_hrtimer kernel/time/hrtimer.c:1496 [inline]
__hrtimer_run_queues+0x250/0x600 kernel/time/hrtimer.c:1576
hrtimer_run_softirq+0x10e/0x150 kernel/time/hrtimer.c:1593
__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
read to 0xffff8880a3a65588 of 1 bytes by task 22891 on cpu 1:
__tcp_ack_snd_check+0x415/0x4f0 net/ipv4/tcp_input.c:5265
tcp_ack_snd_check net/ipv4/tcp_input.c:5287 [inline]
tcp_rcv_established+0x750/0xf50 net/ipv4/tcp_input.c:5708
tcp_v4_do_rcv+0x381/0x4e0 net/ipv4/tcp_ipv4.c:1561
sk_backlog_rcv include/net/sock.h:945 [inline]
__release_sock+0x135/0x1e0 net/core/sock.c:2435
release_sock+0x61/0x160 net/core/sock.c:2951
sk_stream_wait_memory+0x3d7/0x7c0 net/core/stream.c:145
tcp_sendmsg_locked+0xb47/0x1f30 net/ipv4/tcp.c:1393
tcp_sendmsg+0x39/0x60 net/ipv4/tcp.c:1434
inet_sendmsg+0x6d/0x90 net/ipv4/af_inet.c:807
sock_sendmsg_nosec net/socket.c:637 [inline]
sock_sendmsg+0x9f/0xc0 net/socket.c:657
__sys_sendto+0x21f/0x320 net/socket.c:1952
__do_sys_sendto net/socket.c:1964 [inline]
__se_sys_sendto net/socket.c:1960 [inline]
__x64_sys_sendto+0x89/0xb0 net/socket.c:1960
do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 24652 Comm: syz-executor.3 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[ tglx: Added comments ]
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191106174804.74723-1-edumazet@google.com
---
include/linux/hrtimer.h | 14 ++++++++++----
kernel/time/hrtimer.c | 11 +++++++----
2 files changed, 17 insertions(+), 8 deletions(-)
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 1b9a51a..1f98b52 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -456,12 +456,18 @@ extern u64 hrtimer_next_event_without(const struct hrtimer *exclude);
extern bool hrtimer_active(const struct hrtimer *timer);
-/*
- * Helper function to check, whether the timer is on one of the queues
+/**
+ * hrtimer_is_queued = check, whether the timer is on one of the queues
+ * @timer: Timer to check
+ *
+ * Returns: True if the timer is queued, false otherwise
+ *
+ * The function can be used lockless, but it gives only a current snapshot.
*/
-static inline int hrtimer_is_queued(struct hrtimer *timer)
+static inline bool hrtimer_is_queued(struct hrtimer *timer)
{
- return timer->state & HRTIMER_STATE_ENQUEUED;
+ /* The READ_ONCE pairs with the update functions of timer->state */
+ return !!(READ_ONCE(timer->state) & HRTIMER_STATE_ENQUEUED);
}
/*
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 6560553..7f31932 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -966,7 +966,8 @@ static int enqueue_hrtimer(struct hrtimer *timer,
base->cpu_base->active_bases |= 1 << base->index;
- timer->state = HRTIMER_STATE_ENQUEUED;
+ /* Pairs with the lockless read in hrtimer_is_queued() */
+ WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
return timerqueue_add(&base->active, &timer->node);
}
@@ -988,7 +989,8 @@ static void __remove_hrtimer(struct hrtimer *timer,
struct hrtimer_cpu_base *cpu_base = base->cpu_base;
u8 state = timer->state;
- timer->state = newstate;
+ /* Pairs with the lockless read in hrtimer_is_queued() */
+ WRITE_ONCE(timer->state, newstate);
if (!(state & HRTIMER_STATE_ENQUEUED))
return;
@@ -1013,8 +1015,9 @@ static void __remove_hrtimer(struct hrtimer *timer,
static inline int
remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, bool restart)
{
- if (hrtimer_is_queued(timer)) {
- u8 state = timer->state;
+ u8 state = timer->state;
+
+ if (state & HRTIMER_STATE_ENQUEUED) {
int reprogram;
/*
next prev parent reply other threads:[~2019-11-06 22:24 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-06 17:48 [PATCH] hrtimer: Annotate lockless access to timer->state Eric Dumazet
2019-11-06 18:09 ` Thomas Gleixner
2019-11-06 18:19 ` Eric Dumazet
2019-11-06 19:15 ` Thomas Gleixner
2019-11-06 20:00 ` Eric Dumazet
2019-11-06 21:06 ` [tip: timers/core] " tip-bot2 for Eric Dumazet
2019-11-06 22:02 ` Eric Dumazet
2019-11-06 22:16 ` Thomas Gleixner
2019-11-06 22:24 ` tip-bot2 for Eric Dumazet [this message]
2019-11-06 22:53 ` Eric Dumazet
2019-11-06 22:59 ` Eric Dumazet
2019-11-07 8:52 ` Paul E. McKenney
2019-11-07 15:48 ` Eric Dumazet
2019-11-07 16:11 ` Paul E. McKenney
2019-11-07 16:35 ` Eric Dumazet
2019-11-07 16:39 ` Eric Dumazet
2019-11-07 16:54 ` Paul E. McKenney
2019-11-07 16:59 ` Eric Dumazet
2019-11-07 17:07 ` Paul E. McKenney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=157307905904.29376.8711513726869840596.tip-bot2@tip-bot2 \
--to=tip-bot2@linutronix.de \
--cc=bp@alien8.de \
--cc=edumazet@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=syzkaller@googlegroups.com \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).