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 | C RM-fixed (* * Result: Never * * This litmus test demonstrates that the old "roach motel" approach * to locking, where code can be freely moved into critical sections, * cannot be used in the Linux kernel. *) { int x; atomic_t y; } P0(int *x, atomic_t *y, spinlock_t *lck) { int r2; spin_lock(lck); r2 = atomic_inc_return(y); WRITE_ONCE(*x, 1); spin_unlock(lck); } P1(int *x, atomic_t *y, spinlock_t *lck) { int r0; int r1; int r2; r0 = READ_ONCE(*x); r1 = READ_ONCE(*x); spin_lock(lck); r2 = atomic_inc_return(y); spin_unlock(lck); } locations [x;0:r2;1:r0;1:r1;1:r2] filter (1:r0=0 /\ 1:r1=1) exists (1:r2=1) |