| Message ID | 20210716114408.17320-3-adrian.hunter@intel.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | driver core: Add ability to delete device links of unregistered devices | expand |
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c > index 708b3b62fc4d..9864a8ee0263 100644 > --- a/drivers/scsi/ufs/ufshcd.c > +++ b/drivers/scsi/ufs/ufshcd.c > @@ -5020,15 +5020,34 @@ static int ufshcd_slave_configure(struct scsi_device > *sdev) > static void ufshcd_slave_destroy(struct scsi_device *sdev) > { > struct ufs_hba *hba; > + unsigned long flags; > > hba = shost_priv(sdev->host); > /* Drop the reference as it won't be needed anymore */ > if (ufshcd_scsi_to_upiu_lun(sdev->lun) == UFS_UPIU_UFS_DEVICE_WLUN) { > - unsigned long flags; > - > spin_lock_irqsave(hba->host->host_lock, flags); > hba->sdev_ufs_device = NULL; > spin_unlock_irqrestore(hba->host->host_lock, flags); > + } else if (hba->sdev_ufs_device) { > + struct device *supplier = NULL; > + > + /* Ensure UFS Device WLUN exists and does not disappear */ > + spin_lock_irqsave(hba->host->host_lock, flags); > + if (hba->sdev_ufs_device) { Was just checked in the outer clause? Thanks, Avri > + supplier = &hba->sdev_ufs_device->sdev_gendev; > + get_device(supplier); > + } > + spin_unlock_irqrestore(hba->host->host_lock, flags); > + > + if (supplier) { > + /* > + * If a LUN fails to probe (e.g. absent BOOT WLUN), the > + * device will not have been registered but can still > + * have a device link holding a reference to the device. > + */ > + device_link_remove(&sdev->sdev_gendev, supplier); > + put_device(supplier); > + } > } > } > > -- > 2.17.1
Martin, perhaps you could consider picking up this patch if no one objects? On 16/07/21 2:44 pm, Adrian Hunter wrote: > Managed device links are deleted by device_del(). However it is possible to > add a device link to a consumer before device_add(), and then discovering > an error prevents the device from being used. In that case normally > references to the device would be dropped and the device would be deleted. > However the device link holds a reference to the device, so the device link > and device remain indefinitely (unless the supplier is deleted). > > For UFSHCD, if a LUN fails to probe (e.g. absent BOOT WLUN), the device > will not have been registered but can still have a device link holding a > reference to the device. The unwanted device link will prevent runtime > suspend indefinitely. > > Amend device link removal to accept removal of a link with an unregistered > consumer device (suggested by Rafael), and fix UFSHCD by explicitly > deleting the device link when SCSI destroys the SCSI device. > > Fixes: b294ff3e34490 ("scsi: ufs: core: Enable power management for wlun") > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > Reviewed-by: Rafael J. Wysocki <rafael@kernel.org> > --- > drivers/base/core.c | 2 ++ > drivers/scsi/ufs/ufshcd.c | 23 +++++++++++++++++++++-- > 2 files changed, 23 insertions(+), 2 deletions(-) > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index 2de8f7d8cf54..983e895d4ced 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -887,6 +887,8 @@ static void device_link_put_kref(struct device_link *link) > { > if (link->flags & DL_FLAG_STATELESS) > kref_put(&link->kref, __device_link_del); > + else if (!device_is_registered(link->consumer)) > + __device_link_del(&link->kref); > else > WARN(1, "Unable to drop a managed device link reference\n"); > } > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c > index 708b3b62fc4d..9864a8ee0263 100644 > --- a/drivers/scsi/ufs/ufshcd.c > +++ b/drivers/scsi/ufs/ufshcd.c > @@ -5020,15 +5020,34 @@ static int ufshcd_slave_configure(struct scsi_device *sdev) > static void ufshcd_slave_destroy(struct scsi_device *sdev) > { > struct ufs_hba *hba; > + unsigned long flags; > > hba = shost_priv(sdev->host); > /* Drop the reference as it won't be needed anymore */ > if (ufshcd_scsi_to_upiu_lun(sdev->lun) == UFS_UPIU_UFS_DEVICE_WLUN) { > - unsigned long flags; > - > spin_lock_irqsave(hba->host->host_lock, flags); > hba->sdev_ufs_device = NULL; > spin_unlock_irqrestore(hba->host->host_lock, flags); > + } else if (hba->sdev_ufs_device) { > + struct device *supplier = NULL; > + > + /* Ensure UFS Device WLUN exists and does not disappear */ > + spin_lock_irqsave(hba->host->host_lock, flags); > + if (hba->sdev_ufs_device) { > + supplier = &hba->sdev_ufs_device->sdev_gendev; > + get_device(supplier); > + } > + spin_unlock_irqrestore(hba->host->host_lock, flags); > + > + if (supplier) { > + /* > + * If a LUN fails to probe (e.g. absent BOOT WLUN), the > + * device will not have been registered but can still > + * have a device link holding a reference to the device. > + */ > + device_link_remove(&sdev->sdev_gendev, supplier); > + put_device(supplier); > + } > } > } > >
On 6/08/21 5:50 am, Martin K. Petersen wrote: > >> Since patch 1/2 went in through Greg's tree, if patch 2/2 goes >> upstream via Martin's tree, will the resulting kernel be bisectable if >> Linus pulls Martin's tree before he pulls Greg's tree? > > Also, this patch will need to be rebased on top of 5.15/scsi-staging due > to all the UFS churn in this release. > Patch "driver core: Prevent warning when removing a device link from unregistered consumer" is already in Linus' tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e64daad660a0c9ace3acdc57099fffe5ed83f977 I will rebase on 5.15/scsi-staging
diff --git a/drivers/base/core.c b/drivers/base/core.c index 2de8f7d8cf54..983e895d4ced 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -887,6 +887,8 @@ static void device_link_put_kref(struct device_link *link) { if (link->flags & DL_FLAG_STATELESS) kref_put(&link->kref, __device_link_del); + else if (!device_is_registered(link->consumer)) + __device_link_del(&link->kref); else WARN(1, "Unable to drop a managed device link reference\n"); } diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index 708b3b62fc4d..9864a8ee0263 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -5020,15 +5020,34 @@ static int ufshcd_slave_configure(struct scsi_device *sdev) static void ufshcd_slave_destroy(struct scsi_device *sdev) { struct ufs_hba *hba; + unsigned long flags; hba = shost_priv(sdev->host); /* Drop the reference as it won't be needed anymore */ if (ufshcd_scsi_to_upiu_lun(sdev->lun) == UFS_UPIU_UFS_DEVICE_WLUN) { - unsigned long flags; - spin_lock_irqsave(hba->host->host_lock, flags); hba->sdev_ufs_device = NULL; spin_unlock_irqrestore(hba->host->host_lock, flags); + } else if (hba->sdev_ufs_device) { + struct device *supplier = NULL; + + /* Ensure UFS Device WLUN exists and does not disappear */ + spin_lock_irqsave(hba->host->host_lock, flags); + if (hba->sdev_ufs_device) { + supplier = &hba->sdev_ufs_device->sdev_gendev; + get_device(supplier); + } + spin_unlock_irqrestore(hba->host->host_lock, flags); + + if (supplier) { + /* + * If a LUN fails to probe (e.g. absent BOOT WLUN), the + * device will not have been registered but can still + * have a device link holding a reference to the device. + */ + device_link_remove(&sdev->sdev_gendev, supplier); + put_device(supplier); + } } }
Managed device links are deleted by device_del(). However it is possible to add a device link to a consumer before device_add(), and then discovering an error prevents the device from being used. In that case normally references to the device would be dropped and the device would be deleted. However the device link holds a reference to the device, so the device link and device remain indefinitely (unless the supplier is deleted). For UFSHCD, if a LUN fails to probe (e.g. absent BOOT WLUN), the device will not have been registered but can still have a device link holding a reference to the device. The unwanted device link will prevent runtime suspend indefinitely. Amend device link removal to accept removal of a link with an unregistered consumer device (suggested by Rafael), and fix UFSHCD by explicitly deleting the device link when SCSI destroys the SCSI device. Fixes: b294ff3e34490 ("scsi: ufs: core: Enable power management for wlun") Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Reviewed-by: Rafael J. Wysocki <rafael@kernel.org> --- drivers/base/core.c | 2 ++ drivers/scsi/ufs/ufshcd.c | 23 +++++++++++++++++++++-- 2 files changed, 23 insertions(+), 2 deletions(-)