| Message ID | 20240408102726.443206-1-nilay@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [PATCHv2] nvme-pci: Fix EEH failure on ppc after subsystem reset | expand |
On 4/8/24 15:56, Nilay Shroff wrote: > If the nvme subsyetm reset causes the loss of communication to the nvme > adapter then EEH could potnetially recover the adapter. The detection of > comminication loss to the adapter only happens when the nvme driver > attempts to read an MMIO register. > > The nvme subsystem reset command writes 0x4E564D65 to NSSR register and > schedule adapter reset.In the case nvme subsystem reset caused the loss > of communication to the nvme adapter then either IO timeout event or > adapter reset handler could detect it. If IO timeout event could detect > loss of communication then EEH handler is able to recover the communication > to the adapter. This change was implemented in commit 651438bb0af5 > ("nvme-pci: Fix EEH failure on ppc"). However if the adapter communication > loss is detected during nvme reset work then EEH is unable to successfully > finish the adapter recovery. > > This patch ensures that, > - nvme reset work can observer pci channel is offline (at-least on the > paltfrom which supports EEH recovery) after a failed MMIO read and > contains reset work forward progress and marking controller state to > DEAD. Thus we give a fair chance to EEH handler to recover the nvme > adapter. > > - if pci channel "frozen" error is detected while controller is already > in the RESETTING state then don't try (re-)setting controller state to > RESETTING which would otherwise obviously fail and we may prematurely > breaks out of the EEH recovery handling. > > - if pci channel "frozen" error is detected while reset work is in progress > then wait until reset work is finished before proceeding with nvme dev > disable. This would ensure that the reset work doesn't race with the > pci error handler code and both error handler and reset work forward > progress without blocking. > > Signed-off-by: Nilay Shroff <nilay@linux.ibm.com> > --- > Changes from v1: > - Allow a controller to reset from a connecting state (Keith) > > - Fix race condition between reset work and pci error handler > code which may contain reset work and EEH recovery from > forward progress (Keith) > > drivers/nvme/host/core.c | 1 + > drivers/nvme/host/pci.c | 19 ++++++++++++++++--- > 2 files changed, 17 insertions(+), 3 deletions(-) > > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c > index 27281a9a8951..b3fe1a02c171 100644 > --- a/drivers/nvme/host/core.c > +++ b/drivers/nvme/host/core.c > @@ -557,6 +557,7 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl, > switch (old_state) { > case NVME_CTRL_NEW: > case NVME_CTRL_LIVE: > + case NVME_CTRL_CONNECTING: > changed = true; > fallthrough; > default: > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c > index 8e0bb9692685..553bf0ec5f5c 100644 > --- a/drivers/nvme/host/pci.c > +++ b/drivers/nvme/host/pci.c > @@ -2776,6 +2776,16 @@ static void nvme_reset_work(struct work_struct *work) > out_unlock: > mutex_unlock(&dev->shutdown_lock); > out: > + /* > + * If PCI recovery is ongoing then let it finish first > + */ > + if (pci_channel_offline(to_pci_dev(dev->dev))) { > + if (nvme_ctrl_state(&dev->ctrl) == NVME_CTRL_RESETTING || > + nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_RESETTING)) { > + dev_warn(dev->ctrl.device, "Let pci error recovery finish!\n"); > + return; > + } > + } > /* > * Set state to deleting now to avoid blocking nvme_wait_reset(), which > * may be holding this pci_dev's device lock. > @@ -3295,10 +3305,13 @@ static pci_ers_result_t nvme_error_detected(struct pci_dev *pdev, > case pci_channel_io_frozen: > dev_warn(dev->ctrl.device, > "frozen state error detected, reset controller\n"); > - if (!nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_RESETTING)) { > - nvme_dev_disable(dev, true); > - return PCI_ERS_RESULT_DISCONNECT; > + if (nvme_ctrl_state(&dev->ctrl) != NVME_CTRL_RESETTING) { > + if (!nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_RESETTING)) { > + nvme_dev_disable(dev, true); > + return PCI_ERS_RESULT_DISCONNECT; > + } > } > + flush_work(&dev->ctrl.reset_work); > nvme_dev_disable(dev, false); > return PCI_ERS_RESULT_NEED_RESET; > case pci_channel_io_perm_failure: A gentle ping... Can I get some feedback? For reference, link to first version of the patch is here: https://lore.kernel.org/all/20240209050342.406184-1-nilay@linux.ibm.com/ Thanks, --Nilay
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 27281a9a8951..b3fe1a02c171 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -557,6 +557,7 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl, switch (old_state) { case NVME_CTRL_NEW: case NVME_CTRL_LIVE: + case NVME_CTRL_CONNECTING: changed = true; fallthrough; default: diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 8e0bb9692685..553bf0ec5f5c 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -2776,6 +2776,16 @@ static void nvme_reset_work(struct work_struct *work) out_unlock: mutex_unlock(&dev->shutdown_lock); out: + /* + * If PCI recovery is ongoing then let it finish first + */ + if (pci_channel_offline(to_pci_dev(dev->dev))) { + if (nvme_ctrl_state(&dev->ctrl) == NVME_CTRL_RESETTING || + nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_RESETTING)) { + dev_warn(dev->ctrl.device, "Let pci error recovery finish!\n"); + return; + } + } /* * Set state to deleting now to avoid blocking nvme_wait_reset(), which * may be holding this pci_dev's device lock. @@ -3295,10 +3305,13 @@ static pci_ers_result_t nvme_error_detected(struct pci_dev *pdev, case pci_channel_io_frozen: dev_warn(dev->ctrl.device, "frozen state error detected, reset controller\n"); - if (!nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_RESETTING)) { - nvme_dev_disable(dev, true); - return PCI_ERS_RESULT_DISCONNECT; + if (nvme_ctrl_state(&dev->ctrl) != NVME_CTRL_RESETTING) { + if (!nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_RESETTING)) { + nvme_dev_disable(dev, true); + return PCI_ERS_RESULT_DISCONNECT; + } } + flush_work(&dev->ctrl.reset_work); nvme_dev_disable(dev, false); return PCI_ERS_RESULT_NEED_RESET; case pci_channel_io_perm_failure:
If the nvme subsyetm reset causes the loss of communication to the nvme adapter then EEH could potnetially recover the adapter. The detection of comminication loss to the adapter only happens when the nvme driver attempts to read an MMIO register. The nvme subsystem reset command writes 0x4E564D65 to NSSR register and schedule adapter reset.In the case nvme subsystem reset caused the loss of communication to the nvme adapter then either IO timeout event or adapter reset handler could detect it. If IO timeout event could detect loss of communication then EEH handler is able to recover the communication to the adapter. This change was implemented in commit 651438bb0af5 ("nvme-pci: Fix EEH failure on ppc"). However if the adapter communication loss is detected during nvme reset work then EEH is unable to successfully finish the adapter recovery. This patch ensures that, - nvme reset work can observer pci channel is offline (at-least on the paltfrom which supports EEH recovery) after a failed MMIO read and contains reset work forward progress and marking controller state to DEAD. Thus we give a fair chance to EEH handler to recover the nvme adapter. - if pci channel "frozen" error is detected while controller is already in the RESETTING state then don't try (re-)setting controller state to RESETTING which would otherwise obviously fail and we may prematurely breaks out of the EEH recovery handling. - if pci channel "frozen" error is detected while reset work is in progress then wait until reset work is finished before proceeding with nvme dev disable. This would ensure that the reset work doesn't race with the pci error handler code and both error handler and reset work forward progress without blocking. Signed-off-by: Nilay Shroff <nilay@linux.ibm.com> --- Changes from v1: - Allow a controller to reset from a connecting state (Keith) - Fix race condition between reset work and pci error handler code which may contain reset work and EEH recovery from forward progress (Keith) drivers/nvme/host/core.c | 1 + drivers/nvme/host/pci.c | 19 ++++++++++++++++--- 2 files changed, 17 insertions(+), 3 deletions(-)