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Diffstat (limited to 'Documentation/litmus-tests/locking/RM-broken.litmus')
| -rw-r--r-- | Documentation/litmus-tests/locking/RM-broken.litmus | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/Documentation/litmus-tests/locking/RM-broken.litmus b/Documentation/litmus-tests/locking/RM-broken.litmus new file mode 100644 index 000000000000..b7ef30cedfe5 --- /dev/null +++ b/Documentation/litmus-tests/locking/RM-broken.litmus @@ -0,0 +1,41 @@ +C RM-broken + +(* + * Result: DEADLOCK + * + * 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; + + spin_lock(lck); + r0 = READ_ONCE(*x); + r1 = READ_ONCE(*x); + 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) |