If _Q_SLOW_VAL has been set, the vCPU state must have been vcpu_hashed. The extra check at the end of __pv_queued_spin_unlock() is unnecessary and can be removed.
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| @@ -267,7 +267,6 @@ static void pv_wait_head(struct qspinlock *lock, struct mcs_spinlock *node) · 266 unmodified lines | |||
| 267 | } | 267 | } |
| 268 | 268 | ||
| 269 | if (!lp) { /* ONCE */ | 269 | if (!lp) { /* ONCE */ |
| 270 | WRITE_ONCE(pn->state, vcpu_hashed); | ||
| 271 | lp = pv_hash(lock, pn); | 270 | lp = pv_hash(lock, pn); |
| 272 | 271 | ||
| 273 | /* | 272 | /* |
| @@ -275,11 +274,9 @@ static void pv_wait_head(struct qspinlock *lock, struct mcs_spinlock *node) · 1 unmodified line | |||
| 275 | * when we observe _Q_SLOW_VAL in __pv_queued_spin_unlock() | 274 | * when we observe _Q_SLOW_VAL in __pv_queued_spin_unlock() |
| 276 | * we'll be sure to be able to observe our hash entry. | 275 | * we'll be sure to be able to observe our hash entry. |
| 277 | * | 276 | * |
| 278 | * [S] pn->state | ||
| 279 | * [S] <hash> [Rmw] l->locked == _Q_SLOW_VAL | 277 | * [S] <hash> [Rmw] l->locked == _Q_SLOW_VAL |
| 280 | * MB RMB | 278 | * MB RMB |
| 281 | * [RmW] l->locked = _Q_SLOW_VAL [L] <unhash> | 279 | * [RmW] l->locked = _Q_SLOW_VAL [L] <unhash> |
| 282 | * [L] pn->state | ||
| 283 | * | 280 | * |
| 284 | * Matches the smp_rmb() in __pv_queued_spin_unlock(). | 281 | * Matches the smp_rmb() in __pv_queued_spin_unlock(). |
| 285 | */ | 282 | */ |
| @@ -364,8 +361,7 @@ __visible void __pv_queued_spin_unlock(struct qspinlock *lock) · 78 unmodified lines | |||
| 364 | * vCPU is harmless other than the additional latency in completing | 361 | * vCPU is harmless other than the additional latency in completing |
| 365 | * the unlock. | 362 | * the unlock. |
| 366 | */ | 363 | */ |
| 367 | if (READ_ONCE(node->state) == vcpu_hashed) | 364 | pv_kick(node->cpu); |
| 368 | pv_kick(node->cpu); | ||
| 369 | } | 365 | } |
| 370 | /* | 366 | /* |
| 371 | * Include the architecture specific callee-save thunk of the | 367 | * Include the architecture specific callee-save thunk of the |