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.
Unified · Split
| @@ -267,7 +267,6 @@ static void pv_wait_head(struct qspinlock *lock, struct mcs_spinlock *node) · 266 unmodified lines | ||
| 267 | 267 | } |
| 268 | 268 | |
| 269 | 269 | if (!lp) { /* ONCE */ |
| 270 | − WRITE_ONCE(pn->state, vcpu_hashed); | |
| 271 | 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 | 274 | * when we observe _Q_SLOW_VAL in __pv_queued_spin_unlock() |
| 276 | 275 | * we'll be sure to be able to observe our hash entry. |
| 277 | 276 | * |
| 278 | − * [S] pn->state | |
| 279 | 277 | * [S] <hash> [Rmw] l->locked == _Q_SLOW_VAL |
| 280 | 278 | * MB RMB |
| 281 | 279 | * [RmW] l->locked = _Q_SLOW_VAL [L] <unhash> |
| 282 | − * [L] pn->state | |
| 283 | 280 | * |
| 284 | 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 | 361 | * vCPU is harmless other than the additional latency in completing |
| 365 | 362 | * the unlock. |
| 366 | 363 | */ |
| 367 | − if (READ_ONCE(node->state) == vcpu_hashed) | |
| 368 | − pv_kick(node->cpu); | |
| 364 | + pv_kick(node->cpu); | |
| 369 | 365 | } |
| 370 | 366 | /* |
| 371 | 367 | * Include the architecture specific callee-save thunk of the |