On 08/06/2012 12:56 PM, Bart Van Assche wrote:
> On 08/04/12 22:36, Mike Christie wrote:
>> On 08/04/2012 03:18 PM, Bart Van Assche wrote:
>>> On 08/04/12 16:46, Mike Christie wrote:
>>>> I think we have to have scsi-ml do a get_device when a sdev is added to
>>>> the starved entry and then do a put_device when it is removed (must do
>>>> these under the host lock for the starved entry case too). I am not sure
>>>> if that is just a hack/papering-over of the problem and there are more
>>>> issues like this.
>>>
>>> That would result in a more complex patch than the patch at the start of
>>> this thread, isn't it ?
>>
>> Yaah, but the original patch in this thread is still racey isn't it?
>
> Indeed. How about the patch below ? Scsi devices are removed from
> starved_list after blk_cleanup_queue() and before put_device(). That
> guarantees that inside scsi_run_queue() get_device() under host lock
> will succeed.
>
> ---
> drivers/scsi/scsi_lib.c | 5 +++++
> drivers/scsi/scsi_sysfs.c | 7 ++++++-
> 2 files changed, 11 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index ffd7773..bd7daec 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -452,10 +452,15 @@ static void scsi_run_queue(struct request_queue *q)
> continue;
> }
>
> + get_device(&sdev->sdev_gendev);
> spin_unlock(shost->host_lock);
> +
> spin_lock(sdev->request_queue->queue_lock);
> __blk_run_queue(sdev->request_queue);
> spin_unlock(sdev->request_queue->queue_lock);
> +
> + put_device(&sdev->sdev_gendev);
> +
> spin_lock(shost->host_lock);
> }
> /* put any unprocessed entries back */
> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> index 093d4f6..44f232e 100644
> --- a/drivers/scsi/scsi_sysfs.c
> +++ b/drivers/scsi/scsi_sysfs.c
> @@ -348,7 +348,6 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
> starget->reap_ref++;
> list_del(&sdev->siblings);
> list_del(&sdev->same_target_siblings);
> - list_del(&sdev->starved_entry);
> spin_unlock_irqrestore(sdev->host->host_lock, flags);
>
> cancel_work_sync(&sdev->event_work);
> @@ -956,6 +955,8 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
> void __scsi_remove_device(struct scsi_device *sdev)
> {
> struct device *dev = &sdev->sdev_gendev;
> + struct Scsi_Host *shost = sdev->host;
> + unsigned long flags;
>
> if (sdev->is_visible) {
> if (scsi_device_set_state(sdev, SDEV_CANCEL) != 0)
> @@ -977,6 +978,10 @@ void __scsi_remove_device(struct scsi_device *sdev)
> blk_cleanup_queue(sdev->request_queue);
> cancel_work_sync(&sdev->requeue_work);
>
> + spin_lock_irqsave(shost->host_lock, flags);
> + list_del(&sdev->starved_entry);
> + spin_unlock_irqrestore(shost->host_lock, flags);
> +
> if (sdev->host->hostt->slave_destroy)
> sdev->host->hostt->slave_destroy(sdev);
> transport_destroy_device(dev);
>
I think the patch will work now.
Reviewed-by: Mike Christie <michaelc@xxxxxxxxxxx>
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