Re: [PATCH] SCSI: don't hold device refcount in IO path

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Wed, Apr 3, 2019 at 12:03 AM Bart Van Assche <bvanassche@xxxxxxx> wrote:
>
> On Tue, 2019-04-02 at 19:48 +0800, Ming Lei wrote:
> > scsi_device's refcount is always grabed in IO path.
>                                    ^^^^^^
>                                    grabbed?
>
> > Turns out it isn't necessary, becasue blk_queue_cleanup() will
> > drain any in-flight IOs, then cancel timeout/requeue work, and
> > SCSI's requeue_work is canceled too in __scsi_remove_device().
> >
> > Also scsi_device won't go away until blk_cleanup_queue() is done.
> >
> > So don't hold the refcount in IO path.
>
> Holding the device reference count was definitely necessary in the past.
> You may want to reflect this in the patch description by mentioning that
> grabbing that reference count is no longer required today because the
> draining mechanism now waits for requeuing to occur. I don't think that
> was the case for the legacy block layer.

You must forget we have switched to blk_queue_enter() for legacy block
layer for a while, :-)


Thanks,
Ming Lei



[Index of Archives]     [Linux RAID]     [Linux SCSI]     [Linux ATA RAID]     [IDE]     [Linux Wireless]     [Linux Kernel]     [ATH6KL]     [Linux Bluetooth]     [Linux Netdev]     [Kernel Newbies]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Device Mapper]

  Powered by Linux