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| author | Ahmed S. Darwish <a.darwish@linutronix.de> | 2020-08-27 13:40:44 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-09-10 11:19:30 +0200 |
| commit | 0c9794c8b6781eb7dad8e19b78c5d4557790597a (patch) | |
| tree | 3ff88ef1eee674882df3e7a174df462ce15f37b0 | |
| parent | 24bf401cebfd630cc9e2c3746e43945e836626f9 (diff) | |
| download | linux-0c9794c8b6781eb7dad8e19b78c5d4557790597a.tar.gz linux-0c9794c8b6781eb7dad8e19b78c5d4557790597a.tar.bz2 linux-0c9794c8b6781eb7dad8e19b78c5d4557790597a.zip | |
seqlock: seqcount latch APIs: Only allow seqcount_latch_t
All latch sequence counter call-sites have now been converted from plain
seqcount_t to the new seqcount_latch_t data type.
Enforce type-safety by modifying seqlock.h latch APIs to only accept
seqcount_latch_t.
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/20200827114044.11173-9-a.darwish@linutronix.de
| -rw-r--r-- | include/linux/seqlock.h | 36 |
1 files changed, 15 insertions, 21 deletions
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 88b917d4ebde..f2a7a467e998 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -620,7 +620,7 @@ static inline void seqcount_latch_init(seqcount_latch_t *s) /** * raw_read_seqcount_latch() - pick even/odd latch data copy - * @s: Pointer to seqcount_t, seqcount_raw_spinlock_t, or seqcount_latch_t + * @s: Pointer to seqcount_latch_t * * See raw_write_seqcount_latch() for details and a full reader/writer * usage example. @@ -629,17 +629,14 @@ static inline void seqcount_latch_init(seqcount_latch_t *s) * picking which data copy to read. The full counter must then be checked * with read_seqcount_latch_retry(). */ -#define raw_read_seqcount_latch(s) \ -({ \ - /* \ - * Pairs with the first smp_wmb() in raw_write_seqcount_latch(). \ - * Due to the dependent load, a full smp_rmb() is not needed. \ - */ \ - _Generic(*(s), \ - seqcount_t: READ_ONCE(((seqcount_t *)s)->sequence), \ - seqcount_raw_spinlock_t: READ_ONCE(((seqcount_raw_spinlock_t *)s)->seqcount.sequence), \ - seqcount_latch_t: READ_ONCE(((seqcount_latch_t *)s)->seqcount.sequence)); \ -}) +static inline unsigned raw_read_seqcount_latch(const seqcount_latch_t *s) +{ + /* + * Pairs with the first smp_wmb() in raw_write_seqcount_latch(). + * Due to the dependent load, a full smp_rmb() is not needed. + */ + return READ_ONCE(s->seqcount.sequence); +} /** * read_seqcount_latch_retry() - end a seqcount_latch_t read section @@ -656,7 +653,7 @@ read_seqcount_latch_retry(const seqcount_latch_t *s, unsigned start) /** * raw_write_seqcount_latch() - redirect latch readers to even/odd copy - * @s: Pointer to seqcount_t, seqcount_raw_spinlock_t, or seqcount_latch_t + * @s: Pointer to seqcount_latch_t * * The latch technique is a multiversion concurrency control method that allows * queries during non-atomic modifications. If you can guarantee queries never @@ -735,14 +732,11 @@ read_seqcount_latch_retry(const seqcount_latch_t *s, unsigned start) * When data is a dynamic data structure; one should use regular RCU * patterns to manage the lifetimes of the objects within. */ -#define raw_write_seqcount_latch(s) \ -{ \ - smp_wmb(); /* prior stores before incrementing "sequence" */ \ - _Generic(*(s), \ - seqcount_t: ((seqcount_t *)s)->sequence++, \ - seqcount_raw_spinlock_t:((seqcount_raw_spinlock_t *)s)->seqcount.sequence++, \ - seqcount_latch_t: ((seqcount_latch_t *)s)->seqcount.sequence++); \ - smp_wmb(); /* increment "sequence" before following stores */ \ +static inline void raw_write_seqcount_latch(seqcount_latch_t *s) +{ + smp_wmb(); /* prior stores before incrementing "sequence" */ + s->seqcount.sequence++; + smp_wmb(); /* increment "sequence" before following stores */ } /* |