From: "tip-bot2 for Ahmed S. Darwish" <tip-bot2@linutronix.de> To: linux-tip-commits@vger.kernel.org Cc: "Ahmed S. Darwish" <a.darwish@linutronix.de>, "Peter Zijlstra (Intel)" <peterz@infradead.org>, x86 <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org> Subject: [tip: locking/core] Documentation: locking: Describe seqlock design and usage Date: Wed, 29 Jul 2020 14:33:42 -0000 Message-ID: <159603322269.4006.16830879503294515268.tip-bot2@tip-bot2> (raw) In-Reply-To: <20200720155530.1173732-2-a.darwish@linutronix.de> The following commit has been merged into the locking/core branch of tip: Commit-ID: 0d24f65e933ca89d55d17f6dbdb2a72ca88f0992 Gitweb: https://git.kernel.org/tip/0d24f65e933ca89d55d17f6dbdb2a72ca88f0992 Author: Ahmed S. Darwish <a.darwish@linutronix.de> AuthorDate: Mon, 20 Jul 2020 17:55:07 +02:00 Committer: Peter Zijlstra <peterz@infradead.org> CommitterDate: Wed, 29 Jul 2020 16:14:22 +02:00 Documentation: locking: Describe seqlock design and usage Proper documentation for the design and usage of sequence counters and sequential locks does not exist. Complete the seqlock.h documentation as follows: - Divide all documentation on a seqcount_t vs. seqlock_t basis. The description for both mechanisms was intermingled, which is incorrect since the usage constrains for each type are vastly different. - Add an introductory paragraph describing the internal design of, and rationale for, sequence counters. - Document seqcount_t writer non-preemptibility requirement, which was not previously documented anywhere, and provide a clear rationale. - Provide template code for seqcount_t and seqlock_t initialization and reader/writer critical sections. - Recommend using seqlock_t by default. It implicitly handles the serialization and non-preemptibility requirements of writers. At seqlock.h: - Remove references to brlocks as they've long been removed from the kernel. - Remove references to gcc-3.x since the kernel's minimum supported gcc version is 4.9. References: 0f6ed63b1707 ("no need to keep brlock macros anymore...") References: 6ec4476ac825 ("Raise gcc version requirement to 4.9") Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200720155530.1173732-2-a.darwish@linutronix.de --- Documentation/locking/index.rst | 1 +- Documentation/locking/seqlock.rst | 170 +++++++++++++++++++++++++++++- include/linux/seqlock.h | 85 +++++++-------- 3 files changed, 211 insertions(+), 45 deletions(-) create mode 100644 Documentation/locking/seqlock.rst diff --git a/Documentation/locking/index.rst b/Documentation/locking/index.rst index d785878..7003bd5 100644 --- a/Documentation/locking/index.rst +++ b/Documentation/locking/index.rst @@ -14,6 +14,7 @@ locking mutex-design rt-mutex-design rt-mutex + seqlock spinlocks ww-mutex-design preempt-locking diff --git a/Documentation/locking/seqlock.rst b/Documentation/locking/seqlock.rst new file mode 100644 index 0000000..366dd36 --- /dev/null +++ b/Documentation/locking/seqlock.rst @@ -0,0 +1,170 @@ +====================================== +Sequence counters and sequential locks +====================================== + +Introduction +============ + +Sequence counters are a reader-writer consistency mechanism with +lockless readers (read-only retry loops), and no writer starvation. They +are used for data that's rarely written to (e.g. system time), where the +reader wants a consistent set of information and is willing to retry if +that information changes. + +A data set is consistent when the sequence count at the beginning of the +read side critical section is even and the same sequence count value is +read again at the end of the critical section. The data in the set must +be copied out inside the read side critical section. If the sequence +count has changed between the start and the end of the critical section, +the reader must retry. + +Writers increment the sequence count at the start and the end of their +critical section. After starting the critical section the sequence count +is odd and indicates to the readers that an update is in progress. At +the end of the write side critical section the sequence count becomes +even again which lets readers make progress. + +A sequence counter write side critical section must never be preempted +or interrupted by read side sections. Otherwise the reader will spin for +the entire scheduler tick due to the odd sequence count value and the +interrupted writer. If that reader belongs to a real-time scheduling +class, it can spin forever and the kernel will livelock. + +This mechanism cannot be used if the protected data contains pointers, +as the writer can invalidate a pointer that the reader is following. + + +.. _seqcount_t: + +Sequence counters (``seqcount_t``) +================================== + +This is the the raw counting mechanism, which does not protect against +multiple writers. Write side critical sections must thus be serialized +by an external lock. + +If the write serialization primitive is not implicitly disabling +preemption, preemption must be explicitly disabled before entering the +write side section. If the read section can be invoked from hardirq or +softirq contexts, interrupts or bottom halves must also be respectively +disabled before entering the write section. + +If it's desired to automatically handle the sequence counter +requirements of writer serialization and non-preemptibility, use +:ref:`seqlock_t` instead. + +Initialization:: + + /* dynamic */ + seqcount_t foo_seqcount; + seqcount_init(&foo_seqcount); + + /* static */ + static seqcount_t foo_seqcount = SEQCNT_ZERO(foo_seqcount); + + /* C99 struct init */ + struct { + .seq = SEQCNT_ZERO(foo.seq), + } foo; + +Write path:: + + /* Serialized context with disabled preemption */ + + write_seqcount_begin(&foo_seqcount); + + /* ... [[write-side critical section]] ... */ + + write_seqcount_end(&foo_seqcount); + +Read path:: + + do { + seq = read_seqcount_begin(&foo_seqcount); + + /* ... [[read-side critical section]] ... */ + + } while (read_seqcount_retry(&foo_seqcount, seq)); + + +.. _seqlock_t: + +Sequential locks (``seqlock_t``) +================================ + +This contains the :ref:`seqcount_t` mechanism earlier discussed, plus an +embedded spinlock for writer serialization and non-preemptibility. + +If the read side section can be invoked from hardirq or softirq context, +use the write side function variants which disable interrupts or bottom +halves respectively. + +Initialization:: + + /* dynamic */ + seqlock_t foo_seqlock; + seqlock_init(&foo_seqlock); + + /* static */ + static DEFINE_SEQLOCK(foo_seqlock); + + /* C99 struct init */ + struct { + .seql = __SEQLOCK_UNLOCKED(foo.seql) + } foo; + +Write path:: + + write_seqlock(&foo_seqlock); + + /* ... [[write-side critical section]] ... */ + + write_sequnlock(&foo_seqlock); + +Read path, three categories: + +1. Normal Sequence readers which never block a writer but they must + retry if a writer is in progress by detecting change in the sequence + number. Writers do not wait for a sequence reader:: + + do { + seq = read_seqbegin(&foo_seqlock); + + /* ... [[read-side critical section]] ... */ + + } while (read_seqretry(&foo_seqlock, seq)); + +2. Locking readers which will wait if a writer or another locking reader + is in progress. A locking reader in progress will also block a writer + from entering its critical section. This read lock is + exclusive. Unlike rwlock_t, only one locking reader can acquire it:: + + read_seqlock_excl(&foo_seqlock); + + /* ... [[read-side critical section]] ... */ + + read_sequnlock_excl(&foo_seqlock); + +3. Conditional lockless reader (as in 1), or locking reader (as in 2), + according to a passed marker. This is used to avoid lockless readers + starvation (too much retry loops) in case of a sharp spike in write + activity. First, a lockless read is tried (even marker passed). If + that trial fails (odd sequence counter is returned, which is used as + the next iteration marker), the lockless read is transformed to a + full locking read and no retry loop is necessary:: + + /* marker; even initialization */ + int seq = 0; + do { + read_seqbegin_or_lock(&foo_seqlock, &seq); + + /* ... [[read-side critical section]] ... */ + + } while (need_seqretry(&foo_seqlock, seq)); + done_seqretry(&foo_seqlock, seq); + + +API documentation +================= + +.. kernel-doc:: include/linux/seqlock.h diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 8b97204..299d68f 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -1,36 +1,15 @@ /* SPDX-License-Identifier: GPL-2.0 */ #ifndef __LINUX_SEQLOCK_H #define __LINUX_SEQLOCK_H + /* - * Reader/writer consistent mechanism without starving writers. This type of - * lock for data where the reader wants a consistent set of information - * and is willing to retry if the information changes. There are two types - * of readers: - * 1. Sequence readers which never block a writer but they may have to retry - * if a writer is in progress by detecting change in sequence number. - * Writers do not wait for a sequence reader. - * 2. Locking readers which will wait if a writer or another locking reader - * is in progress. A locking reader in progress will also block a writer - * from going forward. Unlike the regular rwlock, the read lock here is - * exclusive so that only one locking reader can get it. - * - * This is not as cache friendly as brlock. Also, this may not work well - * for data that contains pointers, because any writer could - * invalidate a pointer that a reader was following. - * - * Expected non-blocking reader usage: - * do { - * seq = read_seqbegin(&foo); - * ... - * } while (read_seqretry(&foo, seq)); - * - * - * On non-SMP the spin locks disappear but the writer still needs - * to increment the sequence variables because an interrupt routine could - * change the state of the data. - * - * Based on x86_64 vsyscall gettimeofday - * by Keith Owens and Andrea Arcangeli + * seqcount_t / seqlock_t - a reader-writer consistency mechanism with + * lockless readers (read-only retry loops), and no writer starvation. + * + * See Documentation/locking/seqlock.rst + * + * Copyrights: + * - Based on x86_64 vsyscall gettimeofday: Keith Owens, Andrea Arcangeli */ #include <linux/spinlock.h> @@ -41,8 +20,8 @@ #include <asm/processor.h> /* - * The seqlock interface does not prescribe a precise sequence of read - * begin/retry/end. For readers, typically there is a call to + * The seqlock seqcount_t interface does not prescribe a precise sequence of + * read begin/retry/end. For readers, typically there is a call to * read_seqcount_begin() and read_seqcount_retry(), however, there are more * esoteric cases which do not follow this pattern. * @@ -50,16 +29,30 @@ * via seqcount_t under KCSAN: upon beginning a seq-reader critical section, * pessimistically mark the next KCSAN_SEQLOCK_REGION_MAX memory accesses as * atomics; if there is a matching read_seqcount_retry() call, no following - * memory operations are considered atomic. Usage of seqlocks via seqlock_t - * interface is not affected. + * memory operations are considered atomic. Usage of the seqlock_t interface + * is not affected. */ #define KCSAN_SEQLOCK_REGION_MAX 1000 /* - * Version using sequence counter only. - * This can be used when code has its own mutex protecting the - * updating starting before the write_seqcountbeqin() and ending - * after the write_seqcount_end(). + * Sequence counters (seqcount_t) + * + * This is the raw counting mechanism, without any writer protection. + * + * Write side critical sections must be serialized and non-preemptible. + * + * If readers can be invoked from hardirq or softirq contexts, + * interrupts or bottom halves must also be respectively disabled before + * entering the write section. + * + * This mechanism can't be used if the protected data contains pointers, + * as the writer can invalidate a pointer that a reader is following. + * + * If it's desired to automatically handle the sequence counter writer + * serialization and non-preemptibility requirements, use a sequential + * lock (seqlock_t) instead. + * + * See Documentation/locking/seqlock.rst */ typedef struct seqcount { unsigned sequence; @@ -398,10 +391,6 @@ static inline void raw_write_seqcount_latch(seqcount_t *s) smp_wmb(); /* increment "sequence" before following stores */ } -/* - * Sequence counter only version assumes that callers are using their - * own mutexing. - */ static inline void write_seqcount_begin_nested(seqcount_t *s, int subclass) { raw_write_seqcount_begin(s); @@ -434,15 +423,21 @@ static inline void write_seqcount_invalidate(seqcount_t *s) kcsan_nestable_atomic_end(); } +/* + * Sequential locks (seqlock_t) + * + * Sequence counters with an embedded spinlock for writer serialization + * and non-preemptibility. + * + * For more info, see: + * - Comments on top of seqcount_t + * - Documentation/locking/seqlock.rst + */ typedef struct { struct seqcount seqcount; spinlock_t lock; } seqlock_t; -/* - * These macros triggered gcc-3.x compile-time problems. We think these are - * OK now. Be cautious. - */ #define __SEQLOCK_UNLOCKED(lockname) \ { \ .seqcount = SEQCNT_ZERO(lockname), \
next prev parent reply index Thread overview: 258+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-05-19 21:45 [PATCH v1 00/25] seqlock: Extend seqcount API with associated locks Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 01/25] net: core: device_rename: Use rwsem instead of a seqcount Ahmed S. Darwish 2020-05-19 22:01 ` Stephen Hemminger 2020-05-19 22:23 ` Thomas Gleixner 2020-05-19 23:11 ` Stephen Hemminger 2020-05-19 23:42 ` Thomas Gleixner 2020-05-20 0:06 ` Stephen Hemminger 2020-05-20 1:55 ` Thomas Gleixner 2020-05-20 2:57 ` David Miller 2020-05-20 3:18 ` Eric Dumazet 2020-05-20 4:36 ` Stephen Hemminger 2020-05-20 19:37 ` Thomas Gleixner 2020-05-20 21:36 ` Stephen Hemminger 2020-05-20 2:01 ` Eric Dumazet 2020-05-20 6:42 ` Ahmed S. Darwish 2020-05-20 12:51 ` Eric Dumazet 2020-06-03 14:33 ` Ahmed S. Darwish 2020-05-20 14:37 ` Dan Carpenter 2020-05-25 16:22 ` Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 02/25] mm/swap: Don't abuse the seqcount latching API Ahmed S. Darwish 2020-05-20 12:22 ` Konstantin Khlebnikov 2020-05-20 13:05 ` Peter Zijlstra 2020-05-22 14:57 ` Peter Zijlstra 2020-05-22 15:17 ` Sebastian A. Siewior 2020-05-22 16:23 ` Peter Zijlstra 2020-05-25 15:24 ` Ahmed S. Darwish 2020-05-25 15:45 ` Peter Zijlstra 2020-05-25 16:10 ` John Ogness 2020-09-10 15:08 ` [tip: locking/core] mm/swap: Do not abuse the seqcount_t " tip-bot2 for Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 03/25] net: phy: fixed_phy: Remove unused seqcount Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 04/25] block: nr_sects_write(): Disable preemption on seqcount write Ahmed S. Darwish 2020-05-22 16:39 ` Peter Zijlstra 2020-05-25 9:56 ` Ahmed S. Darwish [not found] ` <20200522001237.A00E8206BE@mail.kernel.org> 2020-05-25 10:12 ` Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 05/25] u64_stats: Document writer non-preemptibility requirement Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 06/25] dma-buf: Remove custom seqcount lockdep class key Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 07/25] lockdep: Add preemption disabled assertion API Ahmed S. Darwish 2020-05-22 17:55 ` Peter Zijlstra 2020-05-23 14:59 ` Sebastian A. Siewior 2020-05-23 22:41 ` Peter Zijlstra 2020-05-24 10:50 ` Sebastian A. Siewior 2020-05-25 10:22 ` Peter Zijlstra 2020-05-26 0:52 ` Ahmed S. Darwish 2020-05-26 8:13 ` Peter Zijlstra 2020-05-26 9:45 ` Ahmed S. Darwish 2020-06-03 15:30 ` Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 08/25] seqlock: lockdep assert non-preemptibility on seqcount_t write Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 09/25] Documentation: locking: Describe seqlock design and usage Ahmed S. Darwish 2020-05-22 18:01 ` Peter Zijlstra 2020-05-22 22:24 ` Steven Rostedt 2020-05-25 10:50 ` Ahmed S. Darwish 2020-05-25 11:02 ` Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 10/25] seqlock: Add RST directives to kernel-doc code samples and notes Ahmed S. Darwish 2020-05-22 18:02 ` Peter Zijlstra 2020-05-22 18:03 ` Peter Zijlstra 2020-05-22 18:26 ` Thomas Gleixner 2020-05-22 18:32 ` Peter Zijlstra 2020-05-25 9:36 ` Ahmed S. Darwish 2020-05-25 13:44 ` Peter Zijlstra 2020-05-25 14:07 ` Peter Zijlstra 2020-05-19 21:45 ` [PATCH v1 11/25] seqlock: Add missing kernel-doc annotations Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 12/25] seqlock: Extend seqcount API with associated locks Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 13/25] dma-buf: Use sequence counter with associated wound/wait mutex Ahmed S. Darwish 2020-05-20 10:48 ` Christian König 2020-05-21 0:09 ` Ahmed S. Darwish 2020-05-21 13:20 ` Christian König 2020-05-19 21:45 ` [PATCH v1 14/25] sched: tasks: Use sequence counter with associated spinlock Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 15/25] netfilter: conntrack: " Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 16/25] netfilter: nft_set_rbtree: Use sequence counter with associated rwlock Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 17/25] xfrm: policy: Use sequence counters with associated lock Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 18/25] timekeeping: Use sequence counter with associated raw spinlock Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 19/25] vfs: Use sequence counter with associated spinlock Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 20/25] raid5: " Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 21/25] iocost: " Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 22/25] NFSv4: " Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 23/25] userfaultfd: " Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 24/25] kvm/eventfd: " Ahmed S. Darwish 2020-05-19 21:45 ` [PATCH v1 25/25] hrtimer: Use sequence counter with associated raw spinlock Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 00/18] seqlock: Extend seqcount API with associated locks Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 01/18] Documentation: locking: Describe seqlock design and usage Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 02/18] seqlock: Properly format kernel-doc code samples Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 03/18] seqlock: Add missing kernel-doc annotations Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 04/18] seqlock: Extend seqcount API with associated locks Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 05/18] dma-buf: Remove custom seqcount lockdep class key Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 06/18] dma-buf: Use sequence counter with associated wound/wait mutex Ahmed S. Darwish 2020-06-08 14:32 ` Daniel Vetter 2020-06-08 0:57 ` [PATCH v2 07/18] sched: tasks: Use sequence counter with associated spinlock Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 08/18] netfilter: conntrack: " Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 09/18] netfilter: nft_set_rbtree: Use sequence counter with associated rwlock Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 10/18] xfrm: policy: Use sequence counters with associated lock Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 11/18] timekeeping: Use sequence counter with associated raw spinlock Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 12/18] vfs: Use sequence counter with associated spinlock Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 13/18] raid5: " Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 14/18] iocost: " Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 15/18] NFSv4: " Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 16/18] userfaultfd: " Ahmed S. Darwish 2020-06-08 0:57 ` [PATCH v2 17/18] kvm/eventfd: " Ahmed S. Darwish 2020-06-08 12:57 ` Paolo Bonzini 2020-06-08 0:57 ` [PATCH v2 18/18] hrtimer: Use sequence counter with associated raw spinlock Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 00/20] seqlock: Extend seqcount API with associated locks Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 01/20] Documentation: locking: Describe seqlock design and usage Ahmed S. Darwish 2020-07-06 21:04 ` Peter Zijlstra 2020-07-06 21:12 ` Jonathan Corbet 2020-07-06 21:16 ` Peter Zijlstra 2020-07-07 10:12 ` Ahmed S. Darwish 2020-07-07 12:47 ` Peter Zijlstra 2020-06-30 5:44 ` [PATCH v3 02/20] seqlock: Properly format kernel-doc code samples Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 03/20] seqlock: Add missing kernel-doc annotations Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 04/20] lockdep: Add preemption enabled/disabled assertion APIs Ahmed S. Darwish 2020-07-06 20:50 ` Peter Zijlstra 2020-07-07 7:34 ` Sebastian A. Siewior 2020-06-30 5:44 ` [PATCH v3 05/20] seqlock: lockdep assert non-preemptibility on seqcount_t write Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 06/20] seqlock: Extend seqcount API with associated locks Ahmed S. Darwish 2020-07-06 21:21 ` Peter Zijlstra 2020-07-07 8:40 ` Ahmed S. Darwish 2020-07-07 13:04 ` Peter Zijlstra 2020-07-07 14:37 ` Peter Zijlstra 2020-07-08 9:12 ` Peter Zijlstra 2020-07-08 10:43 ` Ahmed S. Darwish 2020-07-08 10:33 ` Ahmed S. Darwish 2020-07-08 12:29 ` Peter Zijlstra 2020-07-08 14:13 ` Peter Zijlstra 2020-07-08 14:25 ` Peter Zijlstra 2020-07-08 15:09 ` Ahmed S. Darwish 2020-07-08 15:35 ` Peter Zijlstra 2020-07-08 15:58 ` Ahmed S. Darwish 2020-07-08 16:16 ` Peter Zijlstra 2020-07-08 16:18 ` Peter Zijlstra 2020-07-08 16:01 ` Peter Zijlstra 2020-06-30 5:44 ` [PATCH v3 07/20] dma-buf: Remove custom seqcount lockdep class key Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 08/20] dma-buf: Use sequence counter with associated wound/wait mutex Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 09/20] sched: tasks: Use sequence counter with associated spinlock Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 10/20] netfilter: conntrack: " Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 11/20] netfilter: nft_set_rbtree: Use sequence counter with associated rwlock Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 12/20] xfrm: policy: Use sequence counters with associated lock Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 13/20] timekeeping: Use sequence counter with associated raw spinlock Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 14/20] vfs: Use sequence counter with associated spinlock Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 15/20] raid5: " Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 16/20] iocost: " Ahmed S. Darwish 2020-06-30 7:11 ` Daniel Wagner 2020-06-30 5:44 ` [PATCH v3 17/20] NFSv4: " Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 18/20] userfaultfd: " Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 19/20] kvm/eventfd: " Ahmed S. Darwish 2020-06-30 5:44 ` [PATCH v3 20/20] hrtimer: Use sequence counter with associated raw spinlock Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 00/24] seqlock: Extend seqcount API with associated locks Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 01/24] Documentation: locking: Describe seqlock design and usage Ahmed S. Darwish 2020-07-21 1:35 ` Steven Rostedt 2020-07-21 1:37 ` Steven Rostedt 2020-07-21 5:34 ` Ahmed S. Darwish 2020-07-21 1:44 ` Steven Rostedt 2020-07-21 1:51 ` Steven Rostedt 2020-07-21 7:15 ` Ahmed S. Darwish 2020-07-29 14:33 ` tip-bot2 for Ahmed S. Darwish [this message] 2020-07-20 15:55 ` [PATCH v4 02/24] seqlock: Properly format kernel-doc code samples Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 03/24] seqlock: seqcount_t latch: End read sections with read_seqcount_retry() Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 04/24] seqlock: Reorder seqcount_t and seqlock_t API definitions Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 05/24] seqlock: Add kernel-doc for seqcount_t and seqlock_t APIs Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 06/24] seqlock: Implement raw_seqcount_begin() in terms of raw_read_seqcount() Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 07/24] lockdep: Add preemption enabled/disabled assertion APIs Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 08/24] seqlock: lockdep assert non-preemptibility on seqcount_t write Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-08-08 23:21 ` [PATCH v4 08/24] " Guenter Roeck 2020-08-08 23:23 ` Guenter Roeck 2020-08-09 18:42 ` Ahmed S. Darwish 2020-08-10 8:59 ` Greg KH 2020-08-10 9:48 ` peterz 2020-08-10 10:03 ` Greg KH 2020-08-10 9:54 ` [PATCH] Revert "seqlock: lockdep assert non-preemptibility on seqcount_t write" Ahmed S. Darwish 2020-08-10 10:05 ` Greg KH 2020-08-10 10:35 ` Ahmed S. Darwish 2020-08-10 14:10 ` Guenter Roeck 2020-08-18 22:51 ` Valdis Klētnieks 2020-08-19 0:56 ` Guenter Roeck 2020-08-19 7:00 ` Sebastian Andrzej Siewior 2020-08-19 7:34 ` Valdis Klētnieks 2020-08-19 16:15 ` Guenter Roeck 2020-08-10 19:55 ` [PATCH v4 08/24] seqlock: lockdep assert non-preemptibility on seqcount_t write Thomas Gleixner 2020-08-11 10:06 ` Greg KH 2020-07-20 15:55 ` [PATCH v4 09/24] seqlock: Extend seqcount API with associated locks Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 10/24] seqlock: Align multi-line macros newline escapes at 72 columns Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 11/24] dma-buf: Remove custom seqcount lockdep class key Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 12/24] dma-buf: Use sequence counter with associated wound/wait mutex Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 13/24] sched: tasks: Use sequence counter with associated spinlock Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 14/24] netfilter: conntrack: " Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 15/24] netfilter: nft_set_rbtree: Use sequence counter with associated rwlock Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 16/24] xfrm: policy: Use sequence counters with associated lock Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 17/24] timekeeping: Use sequence counter with associated raw spinlock Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 18/24] vfs: Use sequence counter with associated spinlock Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 19/24] raid5: " Ahmed S. Darwish 2020-07-22 6:40 ` Song Liu 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 20/24] iocost: " Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 21/24] NFSv4: " Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 22/24] userfaultfd: " Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 23/24] kvm/eventfd: " Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 15:55 ` [PATCH v4 24/24] hrtimer: Use sequence counter with associated raw spinlock Ahmed S. Darwish 2020-07-29 14:33 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-07-20 16:49 ` [PATCH v4 00/24] seqlock: Extend seqcount API with associated locks Eric Biggers 2020-07-20 17:33 ` Ahmed S. Darwish 2020-08-27 11:40 ` [PATCH v1 0/8] seqlock: Introduce seqcount_latch_t Ahmed S. Darwish 2020-08-27 11:40 ` [PATCH v1 1/8] time/sched_clock: Use raw_read_seqcount_latch() during suspend Ahmed S. Darwish 2020-08-27 11:40 ` [PATCH v1 2/8] mm/swap: Do not abuse the seqcount_t latching API Ahmed S. Darwish 2020-08-27 11:40 ` [PATCH v1 3/8] seqlock: Introduce seqcount_latch_t Ahmed S. Darwish 2020-09-10 15:08 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-08-27 11:40 ` [PATCH v1 4/8] time/sched_clock: Use seqcount_latch_t Ahmed S. Darwish 2020-09-10 15:08 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-08-27 11:40 ` [PATCH v1 5/8] timekeeping: " Ahmed S. Darwish 2020-09-10 15:08 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-08-27 11:40 ` [PATCH v1 6/8] x86/tsc: " Ahmed S. Darwish 2020-09-04 7:41 ` peterz 2020-09-04 8:03 ` peterz 2020-09-07 16:29 ` Ahmed S. Darwish 2020-09-07 17:30 ` peterz 2020-09-08 6:23 ` Ahmed S. Darwish 2020-09-10 15:08 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-08-27 11:40 ` [PATCH v1 7/8] rbtree_latch: " Ahmed S. Darwish 2020-09-10 15:08 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-08-27 11:40 ` [PATCH v1 8/8] seqlock: seqcount latch APIs: Only allow seqcount_latch_t Ahmed S. Darwish 2020-09-10 15:08 ` [tip: locking/core] " tip-bot2 for Ahmed S. Darwish 2020-08-28 1:07 ` [PATCH v1 0/5] seqlock: Introduce PREEMPT_RT support Ahmed S. Darwish 2020-08-28 1:07 ` [PATCH v1 1/5] seqlock: seqcount_LOCKTYPE_t: Standardize naming convention Ahmed S. Darwish 2020-08-28 8:18 ` peterz 2020-08-28 8:24 ` Ahmed S. Darwish 2020-08-28 1:07 ` [PATCH v1 2/5] seqlock: Use unique prefix for seqcount_t property accessors Ahmed S. Darwish 2020-08-28 8:27 ` peterz 2020-08-28 8:59 ` Ahmed S. Darwish 2020-08-28 1:07 ` [PATCH v1 3/5] seqlock: seqcount_t: Implement all read APIs as statement expressions Ahmed S. Darwish 2020-08-28 8:30 ` peterz 2020-08-28 8:37 ` Ahmed S. Darwish 2020-08-28 1:07 ` [PATCH v1 4/5] seqlock: seqcount_LOCKTYPE_t: Introduce PREEMPT_RT support Ahmed S. Darwish 2020-08-28 8:57 ` peterz 2020-08-28 8:59 ` peterz 2020-08-28 9:31 ` Ahmed S. Darwish 2020-08-28 14:36 ` Ahmed S. Darwish 2020-08-28 1:07 ` [PATCH v1 5/5] seqlock: PREEMPT_RT: Do not starve seqlock_t writers Ahmed S. Darwish 2020-09-04 6:52 ` [PATCH v1 0/5] seqlock: Introduce PREEMPT_RT support peterz 2020-09-04 7:30 ` Ahmed S. Darwish 2020-09-10 15:08 ` [tip: locking/core] seqlock: seqcount_LOCKNAME_t: " tip-bot2 for Ahmed S. Darwish
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