diff options
Diffstat (limited to 'arch/tile/lib/spinlock_32.c')
| -rw-r--r-- | arch/tile/lib/spinlock_32.c | 29 |
1 files changed, 18 insertions, 11 deletions
diff --git a/arch/tile/lib/spinlock_32.c b/arch/tile/lib/spinlock_32.c index 485e24d62c6..5cd1c4004ec 100644 --- a/arch/tile/lib/spinlock_32.c +++ b/arch/tile/lib/spinlock_32.c @@ -167,23 +167,30 @@ void arch_write_lock_slow(arch_rwlock_t *rwlock, u32 val) * when we compare them. */ u32 my_ticket_; + u32 iterations = 0; - /* Take out the next ticket; this will also stop would-be readers. */ - if (val & 1) - val = get_rwlock(rwlock); - rwlock->lock = __insn_addb(val, 1 << WR_NEXT_SHIFT); + /* + * Wait until there are no readers, then bump up the next + * field and capture the ticket value. + */ + for (;;) { + if (!(val & 1)) { + if ((val >> RD_COUNT_SHIFT) == 0) + break; + rwlock->lock = val; + } + delay_backoff(iterations++); + val = __insn_tns((int *)&rwlock->lock); + } - /* Extract my ticket value from the original word. */ + /* Take out the next ticket and extract my ticket value. */ + rwlock->lock = __insn_addb(val, 1 << WR_NEXT_SHIFT); my_ticket_ = val >> WR_NEXT_SHIFT; - /* - * Wait until the "current" field matches our ticket, and - * there are no remaining readers. - */ + /* Wait until the "current" field matches our ticket. */ for (;;) { u32 curr_ = val >> WR_CURR_SHIFT; - u32 readers = val >> RD_COUNT_SHIFT; - u32 delta = ((my_ticket_ - curr_) & WR_MASK) + !!readers; + u32 delta = ((my_ticket_ - curr_) & WR_MASK); if (likely(delta == 0)) break; |