| Message ID | 20220826013136.16763-1-mj0123.lee@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/1] blk-mq: added case for cpu offline during send_ipi in rq_complete | expand |
Hello. I think there seems to be a problem that the request complete processing will be omitted due to the follow routine. Please give me a advice or opinion if I get a mistake or missing something. Thank you. > >When a request complete then send ipi to original cpu which issued request. >If cpu offline during this process, send_ipi might fail. >However, there is currently no code to handle this error case. >This may cause in missing request complete. >Therefore, if send_ipi fails due to cpu offline, the request complete >has to be processed directly from the cpu where it is running. > > > >Signed-off-by: Manjong Lee <mj0123.lee@samsung.com> >Signed-off-by: Changheun Lee <nanich.lee@samsung.com> >Signed-off-by: Junho Kim <junho89.kim@samsung.com> >--- > block/blk-mq.c | 16 ++++++++++------ > 1 file changed, 10 insertions(+), 6 deletions(-) > >diff --git a/block/blk-mq.c b/block/blk-mq.c >index 3c1e6b6d991d..f2ce79708c5e 100644 >--- a/block/blk-mq.c >+++ b/block/blk-mq.c >@@ -1064,17 +1064,22 @@ static inline bool blk_mq_complete_need_ipi(struct request *rq) > return cpu_online(rq->mq_ctx->cpu); > } > >-static void blk_mq_complete_send_ipi(struct request *rq) >+static int blk_mq_complete_send_ipi(struct request *rq) > { > struct llist_head *list; > unsigned int cpu; >+ int ret = 0; > > cpu = rq->mq_ctx->cpu; > list = &per_cpu(blk_cpu_done, cpu); > if (llist_add(&rq->ipi_list, list)) { > INIT_CSD(&rq->csd, __blk_mq_complete_request_remote, rq); >- smp_call_function_single_async(cpu, &rq->csd); >+ ret = smp_call_function_single_async(cpu, &rq->csd); >+ if (ret) >+ llist_del_all(list); > } >+ >+ return ret; > } > > static void blk_mq_raise_softirq(struct request *rq) >@@ -1099,10 +1104,9 @@ bool blk_mq_complete_request_remote(struct request *rq) > if (rq->cmd_flags & REQ_POLLED) > return false; > >- if (blk_mq_complete_need_ipi(rq)) { >- blk_mq_complete_send_ipi(rq); >- return true; >- } >+ if (blk_mq_complete_need_ipi(rq)) >+ if (!blk_mq_complete_send_ipi(rq)) >+ return true; > > if (rq->q->nr_hw_queues == 1) { > blk_mq_raise_softirq(rq); >-- >2.32.0 >
diff --git a/block/blk-mq.c b/block/blk-mq.c index 3c1e6b6d991d..f2ce79708c5e 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1064,17 +1064,22 @@ static inline bool blk_mq_complete_need_ipi(struct request *rq) return cpu_online(rq->mq_ctx->cpu); } -static void blk_mq_complete_send_ipi(struct request *rq) +static int blk_mq_complete_send_ipi(struct request *rq) { struct llist_head *list; unsigned int cpu; + int ret = 0; cpu = rq->mq_ctx->cpu; list = &per_cpu(blk_cpu_done, cpu); if (llist_add(&rq->ipi_list, list)) { INIT_CSD(&rq->csd, __blk_mq_complete_request_remote, rq); - smp_call_function_single_async(cpu, &rq->csd); + ret = smp_call_function_single_async(cpu, &rq->csd); + if (ret) + llist_del_all(list); } + + return ret; } static void blk_mq_raise_softirq(struct request *rq) @@ -1099,10 +1104,9 @@ bool blk_mq_complete_request_remote(struct request *rq) if (rq->cmd_flags & REQ_POLLED) return false; - if (blk_mq_complete_need_ipi(rq)) { - blk_mq_complete_send_ipi(rq); - return true; - } + if (blk_mq_complete_need_ipi(rq)) + if (!blk_mq_complete_send_ipi(rq)) + return true; if (rq->q->nr_hw_queues == 1) { blk_mq_raise_softirq(rq);