From: Sasha Levin <Alexander.Levin@microsoft.com>
To: "stable@vger.kernel.org" <stable@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: Andrea Parri <andrea.parri@amarulasolutions.com>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
"akiyks@gmail.com" <akiyks@gmail.com>,
"boqun.feng@gmail.com" <boqun.feng@gmail.com>,
"dhowells@redhat.com" <dhowells@redhat.com>,
"j.alglave@ucl.ac.uk" <j.alglave@ucl.ac.uk>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"luc.maranget@inria.fr" <luc.maranget@inria.fr>,
"npiggin@gmail.com" <npiggin@gmail.com>,
"parri.andrea@gmail.com" <parri.andrea@gmail.com>,
"stern@rowland.harvard.edu" <stern@rowland.harvard.edu>,
"will.deacon@arm.com" <will.deacon@arm.com>,
Ingo Molnar <mingo@kernel.org>,
Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL 4.18 23/92] sched/core: Use smp_mb() in wake_woken_function()
Date: Sat, 15 Sep 2018 01:30:05 +0000 [thread overview]
Message-ID: <20180915012944.179481-23-alexander.levin@microsoft.com> (raw)
In-Reply-To: <20180915012944.179481-1-alexander.levin@microsoft.com>
From: Andrea Parri <andrea.parri@amarulasolutions.com>
[ Upstream commit 76e079fefc8f62bd9b2cd2950814d1ee806e31a5 ]
wake_woken_function() synchronizes with wait_woken() as follows:
[wait_woken] [wake_woken_function]
entry->flags &= ~wq_flag_woken; condition = true;
smp_mb(); smp_wmb();
if (condition) wq_entry->flags |= wq_flag_woken;
break;
This commit replaces the above smp_wmb() with an smp_mb() in order to
guarantee that either wait_woken() sees the wait condition being true
or the store to wq_entry->flags in woken_wake_function() follows the
store in wait_woken() in the coherence order (so that the former can
eventually be observed by wait_woken()).
The commit also fixes a comment associated to set_current_state() in
wait_woken(): the comment pairs the barrier in set_current_state() to
the above smp_wmb(), while the actual pairing involves the barrier in
set_current_state() and the barrier executed by the try_to_wake_up()
in wake_woken_function().
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akiyks@gmail.com
Cc: boqun.feng@gmail.com
Cc: dhowells@redhat.com
Cc: j.alglave@ucl.ac.uk
Cc: linux-arch@vger.kernel.org
Cc: luc.maranget@inria.fr
Cc: npiggin@gmail.com
Cc: parri.andrea@gmail.com
Cc: stern@rowland.harvard.edu
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/20180716180605.16115-10-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
kernel/sched/wait.c | 47 ++++++++++++++++++++-------------------------
1 file changed, 21 insertions(+), 26 deletions(-)
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 928be527477e..a7a2aaa3026a 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -392,35 +392,36 @@ static inline bool is_kthread_should_stop(void)
* if (condition)
* break;
*
- * p->state = mode; condition = true;
- * smp_mb(); // A smp_wmb(); // C
- * if (!wq_entry->flags & WQ_FLAG_WOKEN) wq_entry->flags |= WQ_FLAG_WOKEN;
- * schedule() try_to_wake_up();
- * p->state = TASK_RUNNING; ~~~~~~~~~~~~~~~~~~
- * wq_entry->flags &= ~WQ_FLAG_WOKEN; condition = true;
- * smp_mb() // B smp_wmb(); // C
- * wq_entry->flags |= WQ_FLAG_WOKEN;
- * }
- * remove_wait_queue(&wq_head, &wait);
+ * // in wait_woken() // in woken_wake_function()
*
+ * p->state = mode; wq_entry->flags |= WQ_FLAG_WOKEN;
+ * smp_mb(); // A try_to_wake_up():
+ * if (!(wq_entry->flags & WQ_FLAG_WOKEN)) <full barrier>
+ * schedule() if (p->state & mode)
+ * p->state = TASK_RUNNING; p->state = TASK_RUNNING;
+ * wq_entry->flags &= ~WQ_FLAG_WOKEN; ~~~~~~~~~~~~~~~~~~
+ * smp_mb(); // B condition = true;
+ * } smp_mb(); // C
+ * remove_wait_queue(&wq_head, &wait); wq_entry->flags |= WQ_FLAG_WOKEN;
*/
long wait_woken(struct wait_queue_entry *wq_entry, unsigned mode, long timeout)
{
- set_current_state(mode); /* A */
/*
- * The above implies an smp_mb(), which matches with the smp_wmb() from
- * woken_wake_function() such that if we observe WQ_FLAG_WOKEN we must
- * also observe all state before the wakeup.
+ * The below executes an smp_mb(), which matches with the full barrier
+ * executed by the try_to_wake_up() in woken_wake_function() such that
+ * either we see the store to wq_entry->flags in woken_wake_function()
+ * or woken_wake_function() sees our store to current->state.
*/
+ set_current_state(mode); /* A */
if (!(wq_entry->flags & WQ_FLAG_WOKEN) && !is_kthread_should_stop())
timeout = schedule_timeout(timeout);
__set_current_state(TASK_RUNNING);
/*
- * The below implies an smp_mb(), it too pairs with the smp_wmb() from
- * woken_wake_function() such that we must either observe the wait
- * condition being true _OR_ WQ_FLAG_WOKEN such that we will not miss
- * an event.
+ * The below executes an smp_mb(), which matches with the smp_mb() (C)
+ * in woken_wake_function() such that either we see the wait condition
+ * being true or the store to wq_entry->flags in woken_wake_function()
+ * follows ours in the coherence order.
*/
smp_store_mb(wq_entry->flags, wq_entry->flags & ~WQ_FLAG_WOKEN); /* B */
@@ -430,14 +431,8 @@ EXPORT_SYMBOL(wait_woken);
int woken_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key)
{
- /*
- * Although this function is called under waitqueue lock, LOCK
- * doesn't imply write barrier and the users expects write
- * barrier semantics on wakeup functions. The following
- * smp_wmb() is equivalent to smp_wmb() in try_to_wake_up()
- * and is paired with smp_store_mb() in wait_woken().
- */
- smp_wmb(); /* C */
+ /* Pairs with the smp_store_mb() in wait_woken(). */
+ smp_mb(); /* C */
wq_entry->flags |= WQ_FLAG_WOKEN;
return default_wake_function(wq_entry, mode, sync, key);
--
2.17.1
next prev parent reply other threads:[~2018-09-15 1:50 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-15 1:29 [PATCH AUTOSEL 4.18 01/92] binfmt_elf: Respect error return from `regset->active' Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 02/92] net/mlx5: Add missing SET_DRIVER_VERSION command translation Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 03/92] arm64: dts: uniphier: Add missing cooling device properties for CPUs Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 04/92] audit: fix use-after-free in audit_add_watch Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 05/92] mtdchar: fix overflows in adjustment of `count` Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 06/92] vfs: fix freeze protection in mnt_want_write_file() for overlayfs Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 07/92] bpf: fix rcu annotations in compute_effective_progs() Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 08/92] spi: dw: fix possible race condition Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 10/92] mtd: rawnand: fscm: Avoid collision on PC def when compiling for MIPS Sasha Levin
2018-09-15 17:21 ` Miquel Raynal
2018-09-20 2:32 ` Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 09/92] Bluetooth: Use lock_sock_nested in bt_accept_enqueue Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 11/92] mtd: rawnand: sunxi: Add an U suffix to NFC_PAGE_OP definition Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 12/92] evm: Don't deadlock if a crypto algorithm is unavailable Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 13/92] KVM: PPC: Book3S HV: Add of_node_put() in success path Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 14/92] security: check for kstrdup() failure in lsm_append() Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 15/92] PM / devfreq: use put_device() instead of kfree() Sasha Levin
2018-09-15 1:29 ` [PATCH AUTOSEL 4.18 16/92] KVM: PPC: Book3S: Fix matching of hardware and emulated TCE tables Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 17/92] MIPS: loongson64: cs5536: Fix PCI_OHCI_INT_REG reads Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 18/92] configfs: fix registered group removal Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 19/92] pinctrl: mt7622: Fix probe fail by misuse the selector Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 20/92] pinctrl: rza1: Fix selector use for groups and functions Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 21/92] pinctrl: pinmux: Return selector to the pinctrl driver Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 22/92] arm64: dts: mt7622: update a clock property for UART0 Sasha Levin
2018-09-15 1:30 ` Sasha Levin [this message]
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 24/92] efi/esrt: Only call efi_mem_reserve() for boot services memory Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 25/92] net: hns3: Reset net device with rtnl_lock Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 26/92] net: hns3: Fix for reset_level default assignment probelm Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 27/92] ARM: hisi: handle of_iomap and fix missing of_node_put Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 28/92] ARM: hisi: fix error handling and " Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 29/92] net: hns3: Fix return value error in hns3_reset_notify_down_enet Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 31/92] liquidio: fix hang when re-binding VF host drv after running DPDK VF driver Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 30/92] ARM: hisi: check of_iomap and fix missing of_node_put Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 32/92] gpu: ipu-v3: csi: pass back mbus_code_to_bus_cfg error codes Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 33/92] ASoC: hdmi-codec: fix routing Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 34/92] gpiolib: don't allow userspace to set values of input lines Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 35/92] serial: 8250: of: Correct of_platform_serial_setup() error handling Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 36/92] tty: fix termios input-speed encoding when using BOTHER Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 37/92] tty: fix termios input-speed encoding Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 39/92] mmc: tegra: prevent HS200 on Tegra 3 Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 38/92] mmc: sdhci-of-esdhc: set proper dma mask for ls104x chips Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 40/92] mmc: sdhci: do not try to use 3.3V signaling if not supported Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 41/92] drm/nouveau: Fix runtime PM leak in drm_open() Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 42/92] drm/nouveau/debugfs: Wake up GPU before doing any reclocking Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 43/92] drm/nouveau: tegra: Detach from ARM DMA/IOMMU mapping Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 45/92] parport: sunbpp: fix error return code Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 46/92] sched/fair: Fix util_avg of new tasks for asymmetric systems Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 47/92] coresight: Handle errors in finding input/output ports Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 48/92] coresight: tpiu: Fix disabling timeouts Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 49/92] coresight: ETM: Add support for Arm Cortex-A73 and Cortex-A35 Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 50/92] f2fs: do checkpoint in kill_sb Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 51/92] tools/testing/nvdimm: Fix support for emulating controller temperature Sasha Levin
2018-09-15 1:34 ` Dan Williams
2018-09-15 1:40 ` Sasha Levin
2018-09-15 1:56 ` Dan Williams
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 52/92] drm/amd/display: support access ddc for mst branch Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 53/92] ASoC: qdsp6: q6afe-dai: fix a range check in of_q6afe_parse_dai_data() Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 54/92] lightnvm: pblk: assume that chunks are closed on 1.2 devices Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 55/92] lightnvm: pblk: enable line minor version detection Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 57/92] gpio: pxa: Fix potential NULL dereference Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 56/92] staging: bcm2835-audio: Don't leak workqueue if open fails Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 58/92] gpiolib: Mark gpio_suffixes array with __maybe_unused Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 59/92] net: gemini: Allow multiple ports to instantiate Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 60/92] net: mvpp2: make sure we use single queue mode on PPv2.1 Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 61/92] rcutorture: Use monotonic timestamp for stall detection Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 62/92] mfd: 88pm860x-i2c: switch to i2c_lock_bus(..., I2C_LOCK_SEGMENT) Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 63/92] input: rohm_bu21023: " Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 64/92] rcu: Fix grace-period hangs due to race with CPU offline Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 65/92] drm/amdkfd: Fix kernel queue 64 bit doorbell offset calculation Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 66/92] drm/amdkfd: Fix error codes in kfd_get_process Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 67/92] rtc: bq4802: add error handling for devm_ioremap Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 68/92] selftests: vDSO - fix to return KSFT_SKIP when test couldn't be run Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 70/92] ALSA: pcm: Fix snd_interval_refine first/last with open min/max Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 69/92] selftests/android: initialize heap_type to avoid compiling warning Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 71/92] scsi: libfc: fixup 'sleeping function called from invalid context' Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 73/92] scsi: lpfc: Fix panic if driver unloaded when port is offline Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 72/92] scsi: lpfc: Fix NVME Target crash in defer rcv logic Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 74/92] remoteproc: qcom: q6v5-pil: fix modem hang on SDM845 after axis2 clk unvote Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 75/92] selftest: timers: Tweak raw_skew to SKIP when ADJ_OFFSET/other clock adjustments are in progress Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 76/92] ASoC: rt5651: Fix workqueue cancel vs irq free race on remove Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 77/92] drm/panel: type promotion bug in s6e8aa0_read_mtp_id() Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 78/92] arm64: perf: Disable PMU while processing counter overflows Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 79/92] drm/amd/pp: Send khz clock values to DC for smu7/8 Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 80/92] dmaengine: hsu: Support dmaengine_terminate_sync() Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 81/92] dmaengine: idma64: " Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 82/92] dmaengine: sh: rcar-dmac: avoid to write CHCR.TE to 1 if TCR is set to 0 Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 83/92] staging: fsl-dpaa2/eth: Fix DMA mapping direction Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 84/92] IB/nes: Fix a compiler warning Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 85/92] block/DAC960.c: fix defined but not used build warnings Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 86/92] IB/mlx5: fix uaccess beyond "count" in debugfs read/write handlers Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 87/92] blk-mq: only attempt to merge bio if there is rq in sw queue Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 88/92] blk-mq: avoid to synchronize rcu inside blk_cleanup_queue() Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 89/92] gpiolib: Respect error code of ->get_direction() Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 90/92] pinctrl: msm: Fix msm_config_group_get() to be compliant Sasha Levin
2018-09-15 1:30 ` [PATCH AUTOSEL 4.18 91/92] pinctrl: qcom: spmi-gpio: Fix pmic_gpio_config_get() " Sasha Levin
2018-09-15 1:31 ` [PATCH AUTOSEL 4.18 92/92] clk: tegra: bpmp: Don't crash when a clock fails to register Sasha Levin
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