diff options
Diffstat (limited to 'kernel/rcupdate.c')
| -rw-r--r-- | kernel/rcupdate.c | 30 |
1 files changed, 16 insertions, 14 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index 80cac1cd0859..abb415bb5439 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -49,9 +49,9 @@ /* Definition for rcupdate control block. */ struct rcu_ctrlblk rcu_ctrlblk = - { .cur = -300, .completed = -300 , .lock = SEQCNT_ZERO }; + { .cur = -300, .completed = -300 }; struct rcu_ctrlblk rcu_bh_ctrlblk = - { .cur = -300, .completed = -300 , .lock = SEQCNT_ZERO }; + { .cur = -300, .completed = -300 }; /* Bookkeeping of the progress of the grace period */ struct rcu_state { @@ -185,10 +185,13 @@ static void rcu_start_batch(struct rcu_ctrlblk *rcp, struct rcu_state *rsp, rcp->completed == rcp->cur) { /* Can't change, since spin lock held. */ cpus_andnot(rsp->cpumask, cpu_online_map, nohz_cpu_mask); - write_seqcount_begin(&rcp->lock); + rcp->next_pending = 0; + /* next_pending == 0 must be visible in __rcu_process_callbacks() + * before it can see new value of cur. + */ + smp_wmb(); rcp->cur++; - write_seqcount_end(&rcp->lock); } } @@ -319,8 +322,6 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp, local_irq_disable(); if (rdp->nxtlist && !rdp->curlist) { - int next_pending, seq; - rdp->curlist = rdp->nxtlist; rdp->curtail = rdp->nxttail; rdp->nxtlist = NULL; @@ -330,14 +331,15 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp, /* * start the next batch of callbacks */ - do { - seq = read_seqcount_begin(&rcp->lock); - /* determine batch number */ - rdp->batch = rcp->cur + 1; - next_pending = rcp->next_pending; - } while (read_seqcount_retry(&rcp->lock, seq)); - - if (!next_pending) { + + /* determine batch number */ + rdp->batch = rcp->cur + 1; + /* see the comment and corresponding wmb() in + * the rcu_start_batch() + */ + smp_rmb(); + + if (!rcp->next_pending) { /* and start it/schedule start if it's a new batch */ spin_lock(&rsp->lock); rcu_start_batch(rcp, rsp, 1); |