From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
rostedt@goodmis.org, tglx@linutronix.de,
john.ogness@linutronix.de, pmladek@suse.com
Subject: [PATCH v2 rcu 0/8] NMI-safe SRCU reader API
Date: Thu, 29 Sep 2022 11:07:14 -0700 [thread overview]
Message-ID: <20220929180714.GA2874192@paulmck-ThinkPad-P17-Gen-1> (raw)
In-Reply-To: <20220921144620.GA1200846@paulmck-ThinkPad-P17-Gen-1>
Hello!
This RFC series provides the second version of an NMI-safe SRCU reader API
in the guise of srcu_read_lock_nmisafe() and srcu_read_unlock_nmisafe().
A given srcu_struct structure must use either the traditional
srcu_read_lock() and srcu_read_unlock() API or the new _nmisafe() API:
Mixing and matching is not permitted. So much so that kernels built
with CONFIG_PROVE_RCU=y will complain if you try it.
The reason for this restriction is that I have yet to find a use case
that is not a accident waiting to happen. And if free intermixing
were permitted, it is pretty much a given that someone somewhere will
get confused and use srcu_read_lock_nmisafe() within NMI handlers and
srcu_read_lock() elsewhere, which will not (repeat, NOT) provide NMI
safety.
I do not expect to push this into the v6.1 merge window. However, if
the printk() series that needs it goes in, then I will push it as a fix
for the resulting regression.
The series is as follows:
1. Convert ->srcu_lock_count and ->srcu_unlock_count to atomic.
2. Create an srcu_read_lock_nmisafe() and srcu_read_unlock_nmisafe().
3. Check for consistent per-CPU per-srcu_struct NMI safety.
4. Check for consistent global per-srcu_struct NMI safety.
5. Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option.
6. Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option.
7. Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option.
8. Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option.
Changes since v1 RFC:
1. Added enabling patches for arm64, loongarch, s390, and x86.
These have what appear to me to be NMI-safe this_cpu_inc()
implementations.
2. Fix a build error on !SMP kernels built without SRCU.
3. Fix a build error on !SMP kernels.
Thanx, Paul
------------------------------------------------------------------------
b/arch/arm64/Kconfig | 1
b/arch/loongarch/Kconfig | 1
b/arch/s390/Kconfig | 1
b/arch/x86/Kconfig | 1
b/include/linux/srcu.h | 39 +++++++++++++++++++++
b/include/linux/srcutiny.h | 11 ++++++
b/include/linux/srcutree.h | 4 +-
b/kernel/rcu/Kconfig | 3 +
b/kernel/rcu/rcutorture.c | 11 ++++--
b/kernel/rcu/srcutree.c | 24 ++++++-------
include/linux/srcu.h | 4 +-
include/linux/srcutiny.h | 4 +-
include/linux/srcutree.h | 12 +++++-
kernel/rcu/srcutree.c | 82 +++++++++++++++++++++++++++++++++++++++------
14 files changed, 166 insertions(+), 32 deletions(-)
next prev parent reply other threads:[~2022-09-29 18:07 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-21 14:46 [PATCH rcu 0/4] NMI-safe SRCU reader API Paul E. McKenney
2022-09-21 14:46 ` [PATCH RFC rcu 1/4] srcu: Convert ->srcu_lock_count and ->srcu_unlock_count to atomic Paul E. McKenney
2022-09-21 14:46 ` [PATCH RFC rcu 2/4] srcu: Create and srcu_read_lock_nmisafe() and srcu_read_unlock_nmisafe() Paul E. McKenney
2022-09-21 14:46 ` [PATCH RFC rcu 3/4] srcu: Check for consistent per-CPU per-srcu_struct NMI safety Paul E. McKenney
2022-09-21 14:46 ` [PATCH RFC rcu 4/4] srcu: Check for consistent global " Paul E. McKenney
2022-09-29 18:07 ` Paul E. McKenney [this message]
2022-09-29 18:07 ` [PATCH RFC v2 rcu 1/8] srcu: Convert ->srcu_lock_count and ->srcu_unlock_count to atomic Paul E. McKenney
2022-09-30 15:02 ` John Ogness
2022-09-30 15:35 ` Paul E. McKenney
2022-09-30 20:37 ` John Ogness
2022-10-01 16:51 ` Paul E. McKenney
2022-09-29 18:07 ` [PATCH RFC v2 rcu 2/8] srcu: Create an srcu_read_lock_nmisafe() and srcu_read_unlock_nmisafe() Paul E. McKenney
2022-10-02 15:55 ` Frederic Weisbecker
2022-10-02 15:57 ` Frederic Weisbecker
2022-10-02 16:10 ` Paul E. McKenney
2022-10-02 16:09 ` Paul E. McKenney
2022-10-02 21:47 ` Frederic Weisbecker
2022-10-02 23:46 ` Paul E. McKenney
2022-10-03 9:55 ` Frederic Weisbecker
2022-10-03 11:52 ` Paul E. McKenney
2022-10-18 14:31 ` John Ogness
2022-10-18 15:18 ` Paul E. McKenney
2022-09-29 18:07 ` [PATCH RFC v2 rcu 3/8] srcu: Check for consistent per-CPU per-srcu_struct NMI safety Paul E. McKenney
2022-10-02 22:06 ` Frederic Weisbecker
2022-10-02 23:51 ` Paul E. McKenney
2022-10-03 10:13 ` Frederic Weisbecker
2022-10-03 11:57 ` Paul E. McKenney
2022-10-03 12:37 ` Frederic Weisbecker
2022-10-03 13:32 ` Paul E. McKenney
2022-10-03 13:36 ` Frederic Weisbecker
2022-09-29 18:07 ` [PATCH RFC v2 rcu 4/8] srcu: Check for consistent global " Paul E. McKenney
2022-09-29 18:07 ` [PATCH RFC v2 rcu 5/8] arch/x86: Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option Paul E. McKenney
2022-09-29 18:07 ` [PATCH RFC v2 rcu 6/8] arch/arm64: " Paul E. McKenney
2022-10-05 11:12 ` Mark Rutland
2022-09-29 18:07 ` [PATCH RFC v2 rcu 7/8] arch/loongarch: " Paul E. McKenney
2022-09-29 18:07 ` [PATCH RFC v2 rcu 8/8] arch/s390: " Paul E. McKenney
2022-10-03 14:11 ` [PATCH v2 rcu 0/8] NMI-safe SRCU reader API Frederic Weisbecker
2022-10-03 16:38 ` Paul E. McKenney
2022-10-14 22:47 ` Joel Fernandes
2022-10-14 22:52 ` Joel Fernandes
2022-10-18 10:33 ` John Ogness
2022-10-18 15:24 ` Paul E. McKenney
2022-10-18 18:44 ` John Ogness
2022-10-18 18:59 ` Paul E. McKenney
2022-10-18 21:57 ` Paul E. McKenney
2022-10-19 11:13 ` John Ogness
2022-10-19 19:14 ` Paul E. McKenney
2022-10-19 21:38 ` John Ogness
2022-10-19 22:05 ` Frederic Weisbecker
2022-10-20 22:27 ` Paul E. McKenney
2022-10-20 22:41 ` Paul E. McKenney
2022-10-21 12:27 ` John Ogness
2022-10-21 13:59 ` Paul E. McKenney
2022-10-21 18:41 ` Paul E. McKenney
2022-10-24 6:15 ` John Ogness
2022-10-24 13:47 ` Paul E. McKenney
2022-10-27 9:31 ` John Ogness
2022-10-27 14:10 ` Paul E. McKenney
2022-10-27 14:39 ` John Ogness
2022-10-27 16:01 ` Paul E. McKenney
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