Based on kernel version 6.9
. Page generated on 2024-05-14 10:02 EST
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 | C DCL-broken (* * Result: Sometimes * * This litmus test demonstrates more than just locking is required to * correctly implement double-checked locking. *) { int flag; int data; } P0(int *flag, int *data, spinlock_t *lck) { int r0; int r1; int r2; r0 = READ_ONCE(*flag); if (r0 == 0) { spin_lock(lck); r1 = READ_ONCE(*flag); if (r1 == 0) { WRITE_ONCE(*data, 1); WRITE_ONCE(*flag, 1); } spin_unlock(lck); } r2 = READ_ONCE(*data); } P1(int *flag, int *data, spinlock_t *lck) { int r0; int r1; int r2; r0 = READ_ONCE(*flag); if (r0 == 0) { spin_lock(lck); r1 = READ_ONCE(*flag); if (r1 == 0) { WRITE_ONCE(*data, 1); WRITE_ONCE(*flag, 1); } spin_unlock(lck); } r2 = READ_ONCE(*data); } locations [flag;data;0:r0;0:r1;1:r0;1:r1] exists (0:r2=0 \/ 1:r2=0) |