On Thu, Apr 5, 2012 at 4:32 PM, Aaron Lu <aaron.lu@xxxxxxx> wrote:
> Hi,
>
> On Thu, Apr 05, 2012 at 02:00:57PM +0800, Lin Ming wrote:
>> >
>> > Another thing to consider is, user might want to eject the tray by
>> > software like the
>> > eject /dev/sr0 command or some UI mouse clicks against the cdrom icon. I'm still
>> > thinking how to do this correctly.
>>
>> Assume eject /dev/sr0 is implemented as:
>>
>> int fd = open("/dev/sr0", ...)
>> ioctl(fd, CDROMEJECT)
>>
>
> Indeed, it is implemented as this :-)
>
>> We may need to resume ODD in the ioctl handler(scsi_cmd_ioctl).
>>
>
> I prefer we do this in sr_block_ioctl.
That's better.
> Suppose the ODD is now runtime suspended and received an ioctl:
> if the ioctl's cmd is CDROMEJECT, resume it.
> For other cases, return an error code like EPERM.
> When done, according to the result of ioctl: if success, leave it resumed;
> if failed, put it back to sleep.
>
> Something like this:
>
> diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
> index 5fc97d2..aa6e920 100644
> --- a/drivers/scsi/sr.c
> +++ b/drivers/scsi/sr.c
> @@ -45,6 +45,7 @@
> #include <linux/blkdev.h>
> #include <linux/mutex.h>
> #include <linux/slab.h>
> +#include <linux/pm_runtime.h>
> #include <asm/uaccess.h>
>
> #include <scsi/scsi.h>
> @@ -538,10 +539,21 @@ static int sr_block_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
> struct scsi_cd *cd = scsi_cd(bdev->bd_disk);
> struct scsi_device *sdev = cd->device;
> void __user *argp = (void __user *)arg;
> - int ret;
> + int ret, rpm_resumed = 0;
>
> mutex_lock(&sr_mutex);
>
> + if (pm_runtime_suspended(&sdev->sdev_gendev)) {
> + if (cmd == CDROMEJECT) {
> + scsi_autopm_get_device(sdev);
> + rpm_resumed = 1;
> + }
> + else {
> + ret = -EPERM;
> + goto out;
> + }
> + }
> +
> /*
> * Send SCSI addressing ioctls directly to mid level, send other
> * ioctls to cdrom/block level.
> @@ -570,6 +582,9 @@ static int sr_block_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
> ret = scsi_ioctl(sdev, cmd, argp);
>
> out:
> + if (rpm_resumed && ret)
> + scsi_autopm_put_device(sdev);
> +
> mutex_unlock(&sr_mutex);
> return ret;
> }
>
> Does this work?
I think so.
Will add this patch.
Thanks,
Lin Ming
>
> -Aaron
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