diff options
Diffstat (limited to 'net/sunrpc/svc_xprt.c')
| -rw-r--r-- | net/sunrpc/svc_xprt.c | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index 4eb8fbf2508d..61530b1b7754 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -357,15 +357,29 @@ static void svc_xprt_release_slot(struct svc_rqst *rqstp) struct svc_xprt *xprt = rqstp->rq_xprt; if (test_and_clear_bit(RQ_DATA, &rqstp->rq_flags)) { atomic_dec(&xprt->xpt_nr_rqsts); + smp_wmb(); /* See smp_rmb() in svc_xprt_ready() */ svc_xprt_enqueue(xprt); } } -static bool svc_xprt_has_something_to_do(struct svc_xprt *xprt) +static bool svc_xprt_ready(struct svc_xprt *xprt) { - if (xprt->xpt_flags & ((1<<XPT_CONN)|(1<<XPT_CLOSE))) + unsigned long xpt_flags; + + /* + * If another cpu has recently updated xpt_flags, + * sk_sock->flags, xpt_reserved, or xpt_nr_rqsts, we need to + * know about it; otherwise it's possible that both that cpu and + * this one could call svc_xprt_enqueue() without either + * svc_xprt_enqueue() recognizing that the conditions below + * are satisfied, and we could stall indefinitely: + */ + smp_rmb(); + xpt_flags = READ_ONCE(xprt->xpt_flags); + + if (xpt_flags & (BIT(XPT_CONN) | BIT(XPT_CLOSE))) return true; - if (xprt->xpt_flags & ((1<<XPT_DATA)|(1<<XPT_DEFERRED))) { + if (xpt_flags & (BIT(XPT_DATA) | BIT(XPT_DEFERRED))) { if (xprt->xpt_ops->xpo_has_wspace(xprt) && svc_xprt_slots_in_range(xprt)) return true; @@ -381,7 +395,7 @@ void svc_xprt_do_enqueue(struct svc_xprt *xprt) struct svc_rqst *rqstp = NULL; int cpu; - if (!svc_xprt_has_something_to_do(xprt)) + if (!svc_xprt_ready(xprt)) return; /* Mark transport as busy. It will remain in this state until @@ -475,7 +489,7 @@ void svc_reserve(struct svc_rqst *rqstp, int space) if (xprt && space < rqstp->rq_reserved) { atomic_sub((rqstp->rq_reserved - space), &xprt->xpt_reserved); rqstp->rq_reserved = space; - + smp_wmb(); /* See smp_rmb() in svc_xprt_ready() */ svc_xprt_enqueue(xprt); } } |