The following commit has been merged into the locking/core branch of tip: Commit-ID: a1f1066133d85d5f42217cc72a2490bb7aa889c5 Gitweb: https://git.kernel.org/tip/a1f1066133d85d5f42217cc72a2490bb7aa889c5 Author: Ahmed S. Darwish <a.darw...@linutronix.de> AuthorDate: Thu, 27 Aug 2020 13:40:42 +02:00 Committer: Peter Zijlstra <pet...@infradead.org> CommitterDate: Thu, 10 Sep 2020 11:19:29 +02:00
x86/tsc: Use seqcount_latch_t Latch sequence counters have unique read and write APIs, and thus seqcount_latch_t was recently introduced at seqlock.h. Use that new data type instead of plain seqcount_t. This adds the necessary type-safety and ensures that only latching-safe seqcount APIs are to be used. Signed-off-by: Ahmed S. Darwish <a.darw...@linutronix.de> [peterz: unwreck cyc2ns_read_begin()] Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Link: https://lkml.kernel.org/r/20200827114044.11173-7-a.darw...@linutronix.de --- arch/x86/kernel/tsc.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 49d9250..f70dffc 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -54,7 +54,7 @@ struct clocksource *art_related_clocksource; struct cyc2ns { struct cyc2ns_data data[2]; /* 0 + 2*16 = 32 */ - seqcount_t seq; /* 32 + 4 = 36 */ + seqcount_latch_t seq; /* 32 + 4 = 36 */ }; /* fits one cacheline */ @@ -73,14 +73,14 @@ __always_inline void cyc2ns_read_begin(struct cyc2ns_data *data) preempt_disable_notrace(); do { - seq = this_cpu_read(cyc2ns.seq.sequence); + seq = this_cpu_read(cyc2ns.seq.seqcount.sequence); idx = seq & 1; data->cyc2ns_offset = this_cpu_read(cyc2ns.data[idx].cyc2ns_offset); data->cyc2ns_mul = this_cpu_read(cyc2ns.data[idx].cyc2ns_mul); data->cyc2ns_shift = this_cpu_read(cyc2ns.data[idx].cyc2ns_shift); - } while (unlikely(seq != this_cpu_read(cyc2ns.seq.sequence))); + } while (unlikely(seq != this_cpu_read(cyc2ns.seq.seqcount.sequence))); } __always_inline void cyc2ns_read_end(void) @@ -186,7 +186,7 @@ static void __init cyc2ns_init_boot_cpu(void) { struct cyc2ns *c2n = this_cpu_ptr(&cyc2ns); - seqcount_init(&c2n->seq); + seqcount_latch_init(&c2n->seq); __set_cyc2ns_scale(tsc_khz, smp_processor_id(), rdtsc()); } @@ -203,7 +203,7 @@ static void __init cyc2ns_init_secondary_cpus(void) for_each_possible_cpu(cpu) { if (cpu != this_cpu) { - seqcount_init(&c2n->seq); + seqcount_latch_init(&c2n->seq); c2n = per_cpu_ptr(&cyc2ns, cpu); c2n->data[0] = data[0]; c2n->data[1] = data[1];
