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[Qemu-devel] [PULL 16/18] cputlb: remove tb_lock from tlb_flush function


From: Richard Henderson
Subject: [Qemu-devel] [PULL 16/18] cputlb: remove tb_lock from tlb_flush functions
Date: Thu, 14 Jun 2018 09:31:45 -1000

From: "Emilio G. Cota" <address@hidden>

The acquisition of tb_lock was added when the async tlb_flush
was introduced in e3b9ca810 ("cputlb: introduce tlb_flush_* async work.")

tb_lock was there to allow us to do memset() on the tb_jmp_cache's.
However, since f3ced3c5928 ("tcg: consistently access cpu->tb_jmp_cache
atomically") all accesses to tb_jmp_cache are atomic, so tb_lock
is not needed here. Get rid of it.

Reviewed-by: Alex Bennée <address@hidden>
Reviewed-by: Richard Henderson <address@hidden>
Signed-off-by: Emilio G. Cota <address@hidden>
Signed-off-by: Richard Henderson <address@hidden>
---
 accel/tcg/cputlb.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index 05439039e9..f5c3a0926f 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -125,8 +125,6 @@ static void tlb_flush_nocheck(CPUState *cpu)
     atomic_set(&env->tlb_flush_count, env->tlb_flush_count + 1);
     tlb_debug("(count: %zu)\n", tlb_flush_count());
 
-    tb_lock();
-
     memset(env->tlb_table, -1, sizeof(env->tlb_table));
     memset(env->tlb_v_table, -1, sizeof(env->tlb_v_table));
     cpu_tb_jmp_cache_clear(cpu);
@@ -135,8 +133,6 @@ static void tlb_flush_nocheck(CPUState *cpu)
     env->tlb_flush_addr = -1;
     env->tlb_flush_mask = 0;
 
-    tb_unlock();
-
     atomic_mb_set(&cpu->pending_tlb_flush, 0);
 }
 
@@ -180,8 +176,6 @@ static void tlb_flush_by_mmuidx_async_work(CPUState *cpu, 
run_on_cpu_data data)
 
     assert_cpu_is_self(cpu);
 
-    tb_lock();
-
     tlb_debug("start: mmu_idx:0x%04lx\n", mmu_idx_bitmask);
 
     for (mmu_idx = 0; mmu_idx < NB_MMU_MODES; mmu_idx++) {
@@ -197,8 +191,6 @@ static void tlb_flush_by_mmuidx_async_work(CPUState *cpu, 
run_on_cpu_data data)
     cpu_tb_jmp_cache_clear(cpu);
 
     tlb_debug("done\n");
-
-    tb_unlock();
 }
 
 void tlb_flush_by_mmuidx(CPUState *cpu, uint16_t idxmap)
-- 
2.17.1




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