4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Rakesh Pandit rakesh@tuxera.com
[ Upstream commit 82b057caefaff2a891f821a617d939f46e03e844 ]
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.
[ 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.....
This patch addresses the problem by using state of controller to decide whether reset should be queued or not as state change is synchronizated using controller spinlock. Also cancel_work_sync is used to make sure remove cancels the reset_work and waits for it to finish. This patch also changes return value from -ENODEV to more appropriate -EBUSY if nvme_reset fails to change state.
Fixes: c5f6ce97c1210 ("nvme: don't schedule multiple resets") Signed-off-by: Rakesh Pandit rakesh@tuxera.com Reviewed-by: Sagi Grimberg sagi@grimberg.me Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/nvme/host/pci.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)
--- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -1263,7 +1263,7 @@ static bool nvme_should_reset(struct nvm bool nssro = dev->subsystem && (csts & NVME_CSTS_NSSRO);
/* If there is a reset ongoing, we shouldn't reset again. */ - if (work_busy(&dev->reset_work)) + if (dev->ctrl.state == NVME_CTRL_RESETTING) return false;
/* We shouldn't reset unless the controller is on fatal error state @@ -1755,7 +1755,7 @@ static void nvme_reset_work(struct work_ struct nvme_dev *dev = container_of(work, struct nvme_dev, reset_work); int result = -ENODEV;
- if (WARN_ON(dev->ctrl.state == NVME_CTRL_RESETTING)) + if (WARN_ON(dev->ctrl.state != NVME_CTRL_RESETTING)) goto out;
/* @@ -1765,9 +1765,6 @@ static void nvme_reset_work(struct work_ if (dev->ctrl.ctrl_config & NVME_CC_ENABLE) nvme_dev_disable(dev, false);
- if (!nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_RESETTING)) - goto out; - result = nvme_pci_enable(dev); if (result) goto out; @@ -1841,8 +1838,8 @@ static int nvme_reset(struct nvme_dev *d { 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_RESETTING)) + return -EBUSY; if (!queue_work(nvme_workq, &dev->reset_work)) return -EBUSY; return 0; @@ -1944,6 +1941,7 @@ static int nvme_probe(struct pci_dev *pd if (result) goto release_pools;
+ nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_RESETTING); dev_info(dev->ctrl.device, "pci function %s\n", dev_name(&pdev->dev));
queue_work(nvme_workq, &dev->reset_work); @@ -1987,6 +1985,7 @@ static void nvme_remove(struct pci_dev *
nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_DELETING);
+ cancel_work_sync(&dev->reset_work); pci_set_drvdata(pdev, NULL);
if (!pci_device_is_present(pdev)) {