Mercurial > hg > Members > anatofuz > CbC_xv6
comparison src/spinlock.c @ 35:ad1d3b268e2d
update
author | mir3636 |
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date | Fri, 22 Feb 2019 16:32:51 +0900 |
parents | 83c23a36980d |
children | fb3e5a2f76c1 |
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34:a7144583914c | 35:ad1d3b268e2d |
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44 getcallerpcs(get_fp(), lk->pcs); | 44 getcallerpcs(get_fp(), lk->pcs); |
45 | 45 |
46 #endif | 46 #endif |
47 } | 47 } |
48 | 48 |
49 void cbc_acquire(struct spinlock *lk, __code (*next)(int ret)) | |
50 { | |
51 pushcli(); // disable interrupts to avoid deadlock. | |
52 lk->locked = 1; // set the lock status to make the kernel happy | |
53 | |
54 #if 0 | |
55 if(holding(lk)) | |
56 panic("acquire"); | |
57 | |
58 // The xchg is atomic. | |
59 // It also serializes, so that reads after acquire are not | |
60 // reordered before it. | |
61 while(xchg(&lk->locked, 1) != 0) | |
62 ; | |
63 | |
64 // Record info about lock acquisition for debugging. | |
65 lk->cpu = cpu; | |
66 getcallerpcs(get_fp(), lk->pcs); | |
67 | |
68 #endif | |
69 goto next(); | |
70 } | |
71 | |
49 // Release the lock. | 72 // Release the lock. |
73 void cbc_release(struct spinlock *lk, __code (*next)(int ret)) | |
74 { | |
75 #if 0 | |
76 if(!holding(lk)) | |
77 panic("release"); | |
78 | |
79 lk->pcs[0] = 0; | |
80 lk->cpu = 0; | |
81 | |
82 // The xchg serializes, so that reads before release are | |
83 // not reordered after it. The 1996 PentiumPro manual (Volume 3, | |
84 // 7.2) says reads can be carried out speculatively and in | |
85 // any order, which implies we need to serialize here. | |
86 // But the 2007 Intel 64 Architecture Memory Ordering White | |
87 // Paper says that Intel 64 and IA-32 will not move a load | |
88 // after a store. So lock->locked = 0 would work here. | |
89 // The xchg being asm volatile ensures gcc emits it after | |
90 // the above assignments (and after the critical section). | |
91 xchg(&lk->locked, 0); | |
92 #endif | |
93 | |
94 lk->locked = 0; // set the lock state to keep the kernel happy | |
95 popcli(); | |
96 goto next(); | |
97 } | |
98 | |
50 void release(struct spinlock *lk) | 99 void release(struct spinlock *lk) |
51 { | 100 { |
52 #if 0 | 101 #if 0 |
53 if(!holding(lk)) | 102 if(!holding(lk)) |
54 panic("release"); | 103 panic("release"); |