Commit c5f6ce97c1210 tries to address multiple resets but fails as
work_busy doesn't involve any synchronization and can fail. This is
reproducible easily as can be seen by WARNING below which is triggered
with line:
WARN_ON(dev->ctrl.state == NVME_CTRL_RESETTING)
Allowing multiple resets can result in multiple controller removal as
well if different conditions inside nvme_reset_work fail and which
might deadlock on device_release_driver.
This patch introduces new state called NVME_CTRL_SCHED_RESET and uses
it for synchronizing work queue addition (reset_work) as state change
uses controller spinlock.
[ 480.327007] WARNING: CPU: 3 PID: 150 at drivers/nvme/host/pci.c:1900
nvme_reset_work+0x36c/0xec0
[ 480.327008] Modules linked in: rfcomm fuse nf_conntrack_netbios_ns
nf_conntrack_broadcast...
[ 480.327044] btusb videobuf2_core ghash_clmulni_intel snd_hwdep cfg80211
acer_wmi hci_uart..
[ 480.327065] CPU: 3 PID: 150 Comm: kworker/u16:2 Not tainted 4.12.0-rc1+ #13
[ 480.327065] Hardware name: Acer Predator G9-591/Mustang_SLS, BIOS V1.10
03/03/2016
[ 480.327066] Workqueue: nvme nvme_reset_work
[ 480.327067] task: ffff880498ad8000 task.stack: ffffc90002218000
[ 480.327068] RIP: 0010:nvme_reset_work+0x36c/0xec0
[ 480.327069] RSP: 0018:ffffc9000221bdb8 EFLAGS: 00010246
[ 480.327070] RAX: 0000000000460000 RBX: ffff880498a98128 RCX: dead000000000200
[ 480.327070] RDX: 0000000000000001 RSI: ffff8804b1028020 RDI: ffff880498a98128
[ 480.327071] RBP: ffffc9000221be50 R08: 0000000000000000 R09: 0000000000000000
[ 480.327071] R10: ffffc90001963ce8 R11: 000000000000020d R12: ffff880498a98000
[ 480.327072] R13: ffff880498a53500 R14: ffff880498a98130 R15: ffff880498a98128
[ 480.327072] FS: 0000000000000000(0000) GS:ffff8804c1cc0000(0000)
knlGS:0000000000000000
[ 480.327073] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 480.327074] CR2: 00007ffcf3c37f78 CR3: 0000000001e09000 CR4: 00000000003406e0
[ 480.327074] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 480.327075] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 480.327075] Call Trace:
[ 480.327079] ? __switch_to+0x227/0x400
[ 480.327081] process_one_work+0x18c/0x3a0
[ 480.327082] worker_thread+0x4e/0x3b0
[ 480.327084] kthread+0x109/0x140
[ 480.327085] ? process_one_work+0x3a0/0x3a0
[ 480.327087] ? kthread_park+0x60/0x60
[ 480.327102] ret_from_fork+0x2c/0x40
[ 480.327103] Code: e8 5a dc ff ff 85 c0 41 89 c1 0f.....
V3:
- Use new state NVME_CTRL_SCHED_RESET for synchronization (Keith Busch)
- Fix nvme_probe and keep WARN_ON in nvme_reset_work (Christoph Hellwig)
V2: Use controller state to solve the problem (Christoph Hellwig)
Fixes: c5f6ce97c1210 ("nvme: don't schedule multiple resets")
Signed-off-by: Rakesh Pandit <rak...@tuxera.com>
---
drivers/nvme/host/core.c | 12 +++++++++++-
drivers/nvme/host/nvme.h | 1 +
drivers/nvme/host/pci.c | 12 +++++++++---
3 files changed, 21 insertions(+), 4 deletions(-)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index d5e0906..8a9ee6d 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -161,7 +161,7 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
break;
}
break;
- case NVME_CTRL_RESETTING:
+ case NVME_CTRL_SCHED_RESET:
switch (old_state) {
case NVME_CTRL_NEW:
case NVME_CTRL_LIVE:
@@ -172,6 +172,15 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
break;
}
break;
+ case NVME_CTRL_RESETTING:
+ switch (old_state) {
+ case NVME_CTRL_SCHED_RESET:
+ changed = true;
+ /* FALLTHRU */
+ default:
+ break;
+ }
+ break;
case NVME_CTRL_RECONNECTING:
switch (old_state) {
case NVME_CTRL_LIVE:
@@ -1895,6 +1904,7 @@ static ssize_t nvme_sysfs_show_state(struct device *dev,
static const char *const state_name[] = {
[NVME_CTRL_NEW] = "new",
[NVME_CTRL_LIVE] = "live",
+ [NVME_CTRL_SCHED_RESET] = "sched_reset",
[NVME_CTRL_RESETTING] = "resetting",
[NVME_CTRL_RECONNECTING]= "reconnecting",
[NVME_CTRL_DELETING] = "deleting",
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 29c708c..57802a2 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -109,6 +109,7 @@ static inline struct nvme_request *nvme_req(struct request
*req)
enum nvme_ctrl_state {
NVME_CTRL_NEW,
NVME_CTRL_LIVE,
+ NVME_CTRL_SCHED_RESET,
NVME_CTRL_RESETTING,
NVME_CTRL_RECONNECTING,
NVME_CTRL_DELETING,
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 4c2ff2b..2dc5d30 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1366,7 +1366,12 @@ static bool nvme_should_reset(struct nvme_dev *dev, u32
csts)
*/
bool nssro = dev->subsystem && (csts & NVME_CSTS_NSSRO);
- /* If there is a reset ongoing, we shouldn't reset again. */
+ /*
+ * If there is a reset ongoing, we shouldn't reset again. Even though
+ * work_busy provides an advisory hint, nvme_reset is always called
+ * after this and takes care of synchronization using controller state
+ * change.
+ */
if (work_busy(&dev->reset_work))
return false;
@@ -2009,8 +2014,8 @@ static int nvme_reset(struct nvme_dev *dev)
{
if (!dev->ctrl.admin_q || blk_queue_dying(dev->ctrl.admin_q))
return -ENODEV;
- if (work_busy(&dev->reset_work))
- return -ENODEV;
+ if (!nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_SCHED_RESET))
+ return -EBUSY;
if (!queue_work(nvme_workq, &dev->reset_work))
return -EBUSY;
return 0;
@@ -2137,6 +2142,7 @@ static int nvme_probe(struct pci_dev *pdev, const struct
pci_device_id *id)
dev_info(dev->ctrl.device, "pci function %s\n", dev_name(&pdev->dev));
+ nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_SCHED_RESET);
queue_work(nvme_workq, &dev->reset_work);
return 0;
--
2.5.5
