From: Jens Axboe <axboe@kernel.dk>
Date: Mon, 21 May 2018 08:41:52 -0600
Subject: [PATCH] nvme-pci: fix race between poll and IRQ completions
Git-commit: 68fa9dbe0823e4f833ad8ddbb59c9ca279e84d57
Patch-mainline: v4.18-rc1
References: bsc#1104967,FATE#325924
If polling completions are racing with the IRQ triggered by a
completion, the IRQ handler will find no work and return IRQ_NONE.
This can trigger complaints about spurious interrupts:
[ 560.169153] irq 630: nobody cared (try booting with the "irqpoll" option)
[ 560.175988] CPU: 40 PID: 0 Comm: swapper/40 Not tainted 4.17.0-rc2+ #65
[ 560.175990] Hardware name: Intel Corporation S2600STB/S2600STB, BIOS SE5C620.86B.00.01.0010.010920180151 01/09/2018
[ 560.175991] Call Trace:
[ 560.175994] <IRQ>
[ 560.176005] dump_stack+0x5c/0x7b
[ 560.176010] __report_bad_irq+0x30/0xc0
[ 560.176013] note_interrupt+0x235/0x280
[ 560.176020] handle_irq_event_percpu+0x51/0x70
[ 560.176023] handle_irq_event+0x27/0x50
[ 560.176026] handle_edge_irq+0x6d/0x180
[ 560.176031] handle_irq+0xa5/0x110
[ 560.176036] do_IRQ+0x41/0xc0
[ 560.176042] common_interrupt+0xf/0xf
[ 560.176043] </IRQ>
[ 560.176050] RIP: 0010:cpuidle_enter_state+0x9b/0x2b0
[ 560.176052] RSP: 0018:ffffa0ed4659fe98 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffdd
[ 560.176055] RAX: ffff9527beb20a80 RBX: 000000826caee491 RCX: 000000000000001f
[ 560.176056] RDX: 000000826caee491 RSI: 00000000335206ee RDI: 0000000000000000
[ 560.176057] RBP: 0000000000000001 R08: 00000000ffffffff R09: 0000000000000008
[ 560.176059] R10: ffffa0ed4659fe78 R11: 0000000000000001 R12: ffff9527beb29358
[ 560.176060] R13: ffffffffa235d4b8 R14: 0000000000000000 R15: 000000826caed593
[ 560.176065] ? cpuidle_enter_state+0x8b/0x2b0
[ 560.176071] do_idle+0x1f4/0x260
[ 560.176075] cpu_startup_entry+0x6f/0x80
[ 560.176080] start_secondary+0x184/0x1d0
[ 560.176085] secondary_startup_64+0xa5/0xb0
[ 560.176088] handlers:
[ 560.178387] [<00000000efb612be>] nvme_irq [nvme]
[ 560.183019] Disabling IRQ #630
A previous commit removed ->cqe_seen that was handling this case,
but we need to handle this a bit differently due to completions
now running outside the queue lock. Return IRQ_HANDLED from the
IRQ handler, if the completion ring head was moved since we last
saw it.
Fixes: 5cb525c8315f ("nvme-pci: handle completions outside of the queue lock")
Reported-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Tested-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
drivers/nvme/host/pci.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 133fc063d10c..917e1714f7d9 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -160,6 +160,7 @@ struct nvme_queue {
s16 cq_vector;
u16 sq_tail;
u16 cq_head;
+ u16 last_cq_head;
u16 qid;
u8 cq_phase;
u32 *dbbuf_sq_db;
@@ -999,16 +1000,22 @@ static inline bool nvme_process_cq(struct nvme_queue *nvmeq, u16 *start,
static irqreturn_t nvme_irq(int irq, void *data)
{
struct nvme_queue *nvmeq = data;
+ irqreturn_t ret = IRQ_NONE;
u16 start, end;
spin_lock(&nvmeq->cq_lock);
+ if (nvmeq->cq_head != nvmeq->last_cq_head)
+ ret = IRQ_HANDLED;
nvme_process_cq(nvmeq, &start, &end, -1);
+ nvmeq->last_cq_head = nvmeq->cq_head;
spin_unlock(&nvmeq->cq_lock);
- if (start == end)
- return IRQ_NONE;
- nvme_complete_cqes(nvmeq, start, end);
- return IRQ_HANDLED;
+ if (start != end) {
+ nvme_complete_cqes(nvmeq, start, end);
+ return IRQ_HANDLED;
+ }
+
+ return ret;
}
static irqreturn_t nvme_irq_check(int irq, void *data)
--
2.12.3