From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Will Deacon <will@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Hurley <peter@hurleysoftware.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH AUTOSEL 4.14 29/30] tty/ldsem, locking/rwsem: Add missing ACQUIRE to read_failed sleep loop
Date: Fri, 2 Aug 2019 09:24:21 -0400 [thread overview]
Message-ID: <20190802132422.13963-29-sashal@kernel.org> (raw)
In-Reply-To: <20190802132422.13963-1-sashal@kernel.org>
From: Peter Zijlstra <peterz@infradead.org>
[ Upstream commit 952041a8639a7a3a73a2b6573cb8aa8518bc39f8 ]
While reviewing rwsem down_slowpath, Will noticed ldsem had a copy of
a bug we just found for rwsem.
X = 0;
CPU0 CPU1
rwsem_down_read()
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
X = 1;
rwsem_up_write();
rwsem_mark_wake()
atomic_long_add(adjustment, &sem->count);
smp_store_release(&waiter->task, NULL);
if (!waiter.task)
break;
...
}
r = X;
Allows 'r == 0'.
Reported-by: Will Deacon <will@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 4898e640caf0 ("tty: Add timed, writer-prioritized rw semaphore")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/tty_ldsem.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/tty_ldsem.c b/drivers/tty/tty_ldsem.c
index 5c2cec298816b..c6ce34161281a 100644
--- a/drivers/tty/tty_ldsem.c
+++ b/drivers/tty/tty_ldsem.c
@@ -139,8 +139,7 @@ static void __ldsem_wake_readers(struct ld_semaphore *sem)
list_for_each_entry_safe(waiter, next, &sem->read_wait, list) {
tsk = waiter->task;
- smp_mb();
- waiter->task = NULL;
+ smp_store_release(&waiter->task, NULL);
wake_up_process(tsk);
put_task_struct(tsk);
}
@@ -235,7 +234,7 @@ down_read_failed(struct ld_semaphore *sem, long count, long timeout)
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
- if (!waiter.task)
+ if (!smp_load_acquire(&waiter.task))
break;
if (!timeout)
break;
--
2.20.1
next prev parent reply other threads:[~2019-08-02 13:25 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-02 13:23 [PATCH AUTOSEL 4.14 01/30] netfilter: nfnetlink: avoid deadlock due to synchronous request_module Sasha Levin
2019-08-02 13:23 ` [PATCH AUTOSEL 4.14 02/30] vfio-ccw: Set pa_nr to 0 if memory allocation fails for pa_iova_pfn Sasha Levin
2019-08-02 13:23 ` [PATCH AUTOSEL 4.14 03/30] netfilter: Fix rpfilter dropping vrf packets by mistake Sasha Levin
2019-08-02 13:23 ` [PATCH AUTOSEL 4.14 04/30] netfilter: nft_hash: fix symhash with modulus one Sasha Levin
2019-08-02 13:23 ` [PATCH AUTOSEL 4.14 05/30] scripts/sphinx-pre-install: fix script for RHEL/CentOS Sasha Levin
2019-08-02 13:23 ` [PATCH AUTOSEL 4.14 06/30] iscsi_ibft: make ISCSI_IBFT dependson ACPI instead of ISCSI_IBFT_FIND Sasha Levin
2019-08-02 13:23 ` [PATCH AUTOSEL 4.14 07/30] mac80211: don't warn about CW params when not using them Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 08/30] hwmon: (nct6775) Fix register address and added missed tolerance for nct6106 Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 09/30] x86/mm: Check for pfn instead of page in vmalloc_sync_one() Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 10/30] x86/mm: Sync also unmappings in vmalloc_sync_all() Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 11/30] drm/msm: stop abusing dma_map/unmap for cache Sasha Levin
2019-08-02 18:06 ` [Freedreno] " Sean Paul
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 12/30] drm: silence variable 'conn' set but not used Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 13/30] cpufreq/pasemi: fix use-after-free in pas_cpufreq_cpu_init() Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 14/30] s390/qdio: add sanity checks to the fast-requeue path Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 15/30] ALSA: compress: Fix regression on compressed capture streams Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 16/30] ALSA: compress: Prevent bypasses of set_params Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 17/30] ALSA: compress: Don't allow paritial drain operations on capture streams Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 18/30] ALSA: compress: Be more restrictive about when a drain is allowed Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 19/30] perf tools: Fix proper buffer size for feature processing Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 20/30] perf probe: Avoid calling freeing routine multiple times for same pointer Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 21/30] drbd: dynamically allocate shash descriptor Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 22/30] ACPI/IORT: Fix off-by-one check in iort_dev_find_its_id() Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 23/30] ARM: davinci: fix sleep.S build error on ARMv4 Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 24/30] scsi: megaraid_sas: fix panic on loading firmware crashdump Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 25/30] scsi: ibmvfc: fix WARN_ON during event pool release Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 26/30] scsi: scsi_dh_alua: always use a 2 second delay before retrying RTPG Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 27/30] test_firmware: fix a memory leak bug Sasha Levin
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 28/30] sched/fair: Don't free p->numa_faults with concurrent readers Sasha Levin
2019-08-02 13:24 ` Sasha Levin [this message]
2019-08-02 13:24 ` [PATCH AUTOSEL 4.14 30/30] perf/core: Fix creating kernel counters for PMUs that override event->cpu Sasha Levin
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