On Mon, 2020-03-09 at 12:05 -0700, James Bottomley wrote:
> On Mon, 2020-03-09 at 14:14 -0400, Ewan D. Milne wrote:
> > Large queues of I/O to offline devices that are eventually
> > submitted when devices are unblocked result in a many repeated
> > "rejecting I/O to offline device" messages. These messages
> > can fill up the dmesg buffer in crash dumps so no useful
> > prior messages remain. In addition, if a serial console
> > is used, the flood of messages can cause a hard lockup in
> > the console code.
> >
> > Introduce a flag indicating the message has already been logged
> > for the device, and reset the flag when scsi_device_set_state()
> > changes the device state.
> >
> > Signed-off-by: Ewan D. Milne <emilne@xxxxxxxxxx>
> > ---
> > drivers/scsi/scsi_lib.c | 8 ++++++--
> > include/scsi/scsi_device.h | 2 ++
> > 2 files changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> > index 610ee41..d3a6d97 100644
> > --- a/drivers/scsi/scsi_lib.c
> > +++ b/drivers/scsi/scsi_lib.c
> > @@ -1240,8 +1240,11 @@ scsi_prep_state_check(struct scsi_device
> > *sdev, struct request *req)
> > * commands. The device must be brought online
> > * before trying any recovery commands.
> > */
> > - sdev_printk(KERN_ERR, sdev,
> > - "rejecting I/O to offline device\n");
> > + if (!sdev->offline_already) {
> > + sdev->offline_already = 1;
> > + sdev_printk(KERN_ERR, sdev,
> > + "rejecting I/O to offline
> > device\n");
> > + }
>
> Offline->online is a legal transition, so you'll need to clear this
> flag when that happens so we get another offline message if it goes
> offline again.
>
> James
>
That's what resetting the flag in scsi_device_set_state() does.
The only thing that worries me is if some driver manipulates the
sdev->sdev_state value directly.
-Ewan
