From a8de6639169b90e3dc4f27e752a3c5abac5e90da Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Thu, 7 May 2020 23:07:04 +0300 Subject: nvme-pci: fix "slimmer CQ head update" Pre-incrementing ->cq_head can't be done in memory because OOB value can be observed by another context. This devalues space savings compared to original code :-\ $ ./scripts/bloat-o-meter ../vmlinux-000 ../obj/vmlinux add/remove: 0/0 grow/shrink: 0/4 up/down: 0/-32 (-32) Function old new delta nvme_poll_irqdisable 464 456 -8 nvme_poll 455 447 -8 nvme_irq 388 380 -8 nvme_dev_disable 955 947 -8 But the code is minimal now: one read for head, one read for q_depth, one increment, one comparison, single instruction phase bit update and one write for new head. Signed-off-by: Alexey Dobriyan Reported-by: John Garry Tested-by: John Garry Fixes: e2a366a4b0feaeb ("nvme-pci: slimmer CQ head update") Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe --- drivers/nvme/host/pci.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 4e79e412b276..e13c370de830 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -973,9 +973,13 @@ static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx) static inline void nvme_update_cq_head(struct nvme_queue *nvmeq) { - if (++nvmeq->cq_head == nvmeq->q_depth) { + u16 tmp = nvmeq->cq_head + 1; + + if (tmp == nvmeq->q_depth) { nvmeq->cq_head = 0; nvmeq->cq_phase ^= 1; + } else { + nvmeq->cq_head = tmp; } } -- cgit v1.2.3 From 59c7c3caaaf8750df4ec3255082f15eb4e371514 Mon Sep 17 00:00:00 2001 From: Sagi Grimberg Date: Wed, 6 May 2020 15:44:02 -0700 Subject: nvme: fix possible hang when ns scanning fails during error recovery When the controller is reconnecting, the host fails I/O and admin commands as the host cannot reach the controller. ns scanning may revalidate namespaces during that period and it is wrong to remove namespaces due to these failures as we may hang (see 205da2434301). One command that may fail is nvme_identify_ns_descs. Since we return success due to having ns identify descriptor list optional, we continue to compare ns identifiers in nvme_revalidate_disk, obviously fail and return -ENODEV to nvme_validate_ns, which will remove the namespace. Exactly what we don't want to happen. Fixes: 22802bf742c2 ("nvme: Namepace identification descriptor list is optional") Tested-by: Anton Eidelman Signed-off-by: Sagi Grimberg Reviewed-by: Keith Busch Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe --- drivers/nvme/host/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index f2adea96b04c..f3c037f5a9ba 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -1110,7 +1110,7 @@ static int nvme_identify_ns_descs(struct nvme_ctrl *ctrl, unsigned nsid, * Don't treat an error as fatal, as we potentially already * have a NGUID or EUI-64. */ - if (status > 0) + if (status > 0 && !(status & NVME_SC_DNR)) status = 0; goto free_data; } -- cgit v1.2.3