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authorPeter Zijlstra <peterz@infradead.org>2017-05-02 13:22:07 +0200
committerIngo Molnar <mingo@kernel.org>2017-05-15 10:15:15 +0200
commit59eaef78bfea88fcbbd7b9b48ccf513aae1522c3 (patch)
treeeb668f47caa16eab8c3ac280654a28d25890ddee /arch/x86/platform/uv
parent8309f86cd41e8714526867177facf7a316d9be53 (diff)
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) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/platform/uv')
-rw-r--r--arch/x86/platform/uv/tlb_uv.c14
1 files changed, 8 insertions, 6 deletions
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;
}