From 59eaef78bfea88fcbbd7b9b48ccf513aae1522c3 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 2 May 2017 13:22:07 +0200 Subject: x86/tsc: Remodel cyc2ns to use seqcount_latch() Replace the custom multi-value scheme with the more regular seqcount_latch() scheme. Along with scrapping a lot of lines, the latch scheme is better documented and used in more places. The immediate benefit however is not being limited on the update side. The current code has a limit where the writers block which is hit by future changes. Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar --- arch/x86/platform/uv/tlb_uv.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) (limited to 'arch/x86/platform') diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c index 42e65fee5673..795671593528 100644 --- a/arch/x86/platform/uv/tlb_uv.c +++ b/arch/x86/platform/uv/tlb_uv.c @@ -456,12 +456,13 @@ static void reset_with_ipi(struct pnmask *distribution, struct bau_control *bcp) */ static inline unsigned long long cycles_2_ns(unsigned long long cyc) { - struct cyc2ns_data *data = cyc2ns_read_begin(); + struct cyc2ns_data data; unsigned long long ns; - ns = mul_u64_u32_shr(cyc, data->cyc2ns_mul, data->cyc2ns_shift); + cyc2ns_read_begin(&data); + ns = mul_u64_u32_shr(cyc, data.cyc2ns_mul, data.cyc2ns_shift); + cyc2ns_read_end(); - cyc2ns_read_end(data); return ns; } @@ -470,12 +471,13 @@ static inline unsigned long long cycles_2_ns(unsigned long long cyc) */ static inline unsigned long long ns_2_cycles(unsigned long long ns) { - struct cyc2ns_data *data = cyc2ns_read_begin(); + struct cyc2ns_data data; unsigned long long cyc; - cyc = (ns << data->cyc2ns_shift) / data->cyc2ns_mul; + cyc2ns_read_begin(&data); + cyc = (ns << data.cyc2ns_shift) / data.cyc2ns_mul; + cyc2ns_read_end(); - cyc2ns_read_end(data); return cyc; } -- cgit v1.2.3