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Message-ID: <163831372562.11128.2664068146848964404.tip-bot2@tip-bot2>
Date: Tue, 30 Nov 2021 23:08:45 -0000
From: "tip-bot2 for Mark Rutland" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Mark Rutland <mark.rutland@....com>,
Thomas Gleixner <tglx@...utronix.de>,
"Paul E. McKenney" <paulmck@...nel.org>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: core/entry] entry: Snapshot thread flags
The following commit has been merged into the core/entry branch of tip:
Commit-ID: 6ce895128b3bff738fe8d9dd74747a03e319e466
Gitweb: https://git.kernel.org/tip/6ce895128b3bff738fe8d9dd74747a03e319e466
Author: Mark Rutland <mark.rutland@....com>
AuthorDate: Mon, 29 Nov 2021 13:06:44
Committer: Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Wed, 01 Dec 2021 00:06:43 +01:00
entry: Snapshot thread flags
Some thread flags can be set remotely, and so even when IRQs are disabled,
the flags can change under our feet. Generally this is unlikely to cause a
problem in practice, but it is somewhat unsound, and KCSAN will
legitimately warn that there is a data race.
To avoid such issues, a snapshot of the flags has to be taken prior to
using them. Some places already use READ_ONCE() for that, others do not.
Convert them all to the new flag accessor helpers.
Signed-off-by: Mark Rutland <mark.rutland@....com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Paul E. McKenney <paulmck@...nel.org>
Link: https://lore.kernel.org/r/20211129130653.2037928-3-mark.rutland@arm.com
---
include/linux/entry-kvm.h | 2 +-
kernel/entry/common.c | 4 ++--
kernel/entry/kvm.c | 4 ++--
3 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/include/linux/entry-kvm.h b/include/linux/entry-kvm.h
index 0d7865a..07c878d 100644
--- a/include/linux/entry-kvm.h
+++ b/include/linux/entry-kvm.h
@@ -75,7 +75,7 @@ static inline void xfer_to_guest_mode_prepare(void)
*/
static inline bool __xfer_to_guest_mode_work_pending(void)
{
- unsigned long ti_work = READ_ONCE(current_thread_info()->flags);
+ unsigned long ti_work = read_thread_flags();
return !!(ti_work & XFER_TO_GUEST_MODE_WORK);
}
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index d5a61d5..bad7136 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -187,7 +187,7 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
/* Check if any of the above work has queued a deferred wakeup */
tick_nohz_user_enter_prepare();
- ti_work = READ_ONCE(current_thread_info()->flags);
+ ti_work = read_thread_flags();
}
/* Return the latest work state for arch_exit_to_user_mode() */
@@ -196,7 +196,7 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
static void exit_to_user_mode_prepare(struct pt_regs *regs)
{
- unsigned long ti_work = READ_ONCE(current_thread_info()->flags);
+ unsigned long ti_work = read_thread_flags();
lockdep_assert_irqs_disabled();
diff --git a/kernel/entry/kvm.c b/kernel/entry/kvm.c
index 49972ee..96d476e 100644
--- a/kernel/entry/kvm.c
+++ b/kernel/entry/kvm.c
@@ -26,7 +26,7 @@ static int xfer_to_guest_mode_work(struct kvm_vcpu *vcpu, unsigned long ti_work)
if (ret)
return ret;
- ti_work = READ_ONCE(current_thread_info()->flags);
+ ti_work = read_thread_flags();
} while (ti_work & XFER_TO_GUEST_MODE_WORK || need_resched());
return 0;
}
@@ -43,7 +43,7 @@ int xfer_to_guest_mode_handle_work(struct kvm_vcpu *vcpu)
* disabled in the inner loop before going into guest mode. No need
* to disable interrupts here.
*/
- ti_work = READ_ONCE(current_thread_info()->flags);
+ ti_work = read_thread_flags();
if (!(ti_work & XFER_TO_GUEST_MODE_WORK))
return 0;
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