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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@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: locking/core] seqlock: kernel-doc: Specify when preemption is automatically altered
Date: Wed, 09 Dec 2020 18:38:46 -0000
Message-ID: <160753912635.3364.4993279338737835663.tip-bot2@tip-bot2> (raw)
In-Reply-To: <CAHk-=wikhGExmprXgaW+MVXG1zsGpztBbVwOb23vetk41EtTBQ@mail.gmail.com>

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     cb262935a166bdef0ccfe6e2adffa00c0f2d038a
Gitweb:        https://git.kernel.org/tip/cb262935a166bdef0ccfe6e2adffa00c0f2d038a
Author:        Ahmed S. Darwish <a.darwish@linutronix.de>
AuthorDate:    Sun, 06 Dec 2020 17:21:43 +01:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 09 Dec 2020 17:08:49 +01:00

seqlock: kernel-doc: Specify when preemption is automatically altered

The kernel-doc annotations for sequence counters write side functions
are incomplete: they do not specify when preemption is automatically
disabled and re-enabled.

This has confused a number of call-site developers. Fix it.

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/CAHk-=wikhGExmprXgaW+MVXG1zsGpztBbVwOb23vetk41EtTBQ@mail.gmail.com
---
 include/linux/seqlock.h | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index 235cbc6..2f7bb92 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -456,6 +456,8 @@ static inline int do_read_seqcount_retry(const seqcount_t *s, unsigned start)
 /**
  * raw_write_seqcount_begin() - start a seqcount_t write section w/o lockdep
  * @s: Pointer to seqcount_t or any of the seqcount_LOCKNAME_t variants
+ *
+ * Context: check write_seqcount_begin()
  */
 #define raw_write_seqcount_begin(s)					\
 do {									\
@@ -475,6 +477,8 @@ static inline void do_raw_write_seqcount_begin(seqcount_t *s)
 /**
  * raw_write_seqcount_end() - end a seqcount_t write section w/o lockdep
  * @s: Pointer to seqcount_t or any of the seqcount_LOCKNAME_t variants
+ *
+ * Context: check write_seqcount_end()
  */
 #define raw_write_seqcount_end(s)					\
 do {									\
@@ -498,6 +502,7 @@ static inline void do_raw_write_seqcount_end(seqcount_t *s)
  * @subclass: lockdep nesting level
  *
  * See Documentation/locking/lockdep-design.rst
+ * Context: check write_seqcount_begin()
  */
 #define write_seqcount_begin_nested(s, subclass)			\
 do {									\
@@ -519,11 +524,10 @@ static inline void do_write_seqcount_begin_nested(seqcount_t *s, int subclass)
  * write_seqcount_begin() - start a seqcount_t write side critical section
  * @s: Pointer to seqcount_t or any of the seqcount_LOCKNAME_t variants
  *
- * write_seqcount_begin opens a write side critical section of the given
- * seqcount_t.
- *
- * Context: seqcount_t write side critical sections must be serialized and
- * non-preemptible. If readers can be invoked from hardirq or softirq
+ * Context: sequence counter write side sections must be serialized and
+ * non-preemptible. Preemption will be automatically disabled if and
+ * only if the seqcount write serialization lock is associated, and
+ * preemptible.  If readers can be invoked from hardirq or softirq
  * context, interrupts or bottom halves must be respectively disabled.
  */
 #define write_seqcount_begin(s)						\
@@ -545,7 +549,8 @@ static inline void do_write_seqcount_begin(seqcount_t *s)
  * write_seqcount_end() - end a seqcount_t write side critical section
  * @s: Pointer to seqcount_t or any of the seqcount_LOCKNAME_t variants
  *
- * The write section must've been opened with write_seqcount_begin().
+ * Context: Preemption will be automatically re-enabled if and only if
+ * the seqcount write serialization lock is associated, and preemptible.
  */
 #define write_seqcount_end(s)						\
 do {									\

  parent reply index

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <0-v2-dfe9ecdb6c74+2066-gup_fork_jgg@nvidia.com>
2020-10-30 14:46 ` [PATCH v2 1/2] mm: reorganize internal_get_user_pages_fast() Jason Gunthorpe
2020-10-30 16:29   ` Jan Kara
2020-10-30 21:31   ` John Hubbard
2020-10-30 22:36   ` Peter Xu
2020-11-02 22:19 ` [PATCH v2 0/2] Add a seqcount between gup_fast and copy_page_range() Ahmed S. Darwish
2020-11-02 22:39   ` Linus Torvalds
2020-11-02 23:18     ` Ahmed S. Darwish
     [not found] ` <2-v2-dfe9ecdb6c74+2066-gup_fork_jgg@nvidia.com>
2020-10-30 16:51   ` [PATCH v2 2/2] mm: prevent gup_fast from racing with COW during fork Jan Kara
     [not found]     ` <20201030170226.GF2620339@nvidia.com>
2020-11-02  8:31       ` Jan Kara
2020-10-30 22:52   ` Peter Xu
     [not found]     ` <20201030235121.GQ2620339@nvidia.com>
2020-10-31 15:26       ` Peter Xu
2020-11-03  0:33         ` Ahmed S. Darwish
2020-11-03  0:17       ` Ahmed S. Darwish
     [not found]         ` <20201103002532.GL2620339@nvidia.com>
2020-11-03  0:41           ` Ahmed S. Darwish
2020-11-03  2:20             ` John Hubbard
2020-11-03  6:52               ` Ahmed S. Darwish
2020-11-03 17:40                 ` Linus Torvalds
2020-11-04  1:32                   ` Ahmed S. Darwish
2020-11-04  2:01                     ` John Hubbard
2020-11-04  3:17                       ` Ahmed S. Darwish
2020-11-04 18:38                         ` Linus Torvalds
2020-11-04 19:54                           ` Ahmed S. Darwish
2020-12-09 18:38                           ` [tip: locking/core] seqlock: Prefix internal seqcount_t-only macros with a "do_" tip-bot2 for Ahmed S. Darwish
2020-12-09 18:38                           ` tip-bot2 for Ahmed S. Darwish [this message]
2020-11-10 11:53                         ` [PATCH v2 2/2] mm: prevent gup_fast from racing with COW during fork Peter Zijlstra
2020-12-03 10:35                           ` [tip: locking/core] seqlock: Rename __seqprop() users tip-bot2 for Peter Zijlstra
2020-11-03 17:03         ` [PATCH v2 2/2] mm: prevent gup_fast from racing with COW during fork Peter Xu
2020-11-02 23:58   ` Ahmed S. Darwish

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