On Wed, 2015-11-04 at 14:35 -0800, Bart Van Assche wrote: > On 10/30/2015 03:09 PM, Bart Van Assche wrote: > > When dropping a lock while iterating a list we must restart the search > > as other threads could have manipulated the list under us. Without this > > we can get stuck in an endless loop. > > > > This is a slightly modified version of a patch from Christoph Hellwig > > (see also https://www.spinics.net/lists/linux-scsi/msg89416.html). > > > > Reported-by: Johannes Thumshirn <jthumshirn@xxxxxxx> > > Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx> > > Cc: Johannes Thumshirn <jthumshirn@xxxxxxx> > > Cc: Christoph Hellwig <hch@xxxxxx> > > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > > Cc: stable <stable@xxxxxxxxxxxxxxx> > > --- > > drivers/scsi/scsi_sysfs.c | 16 ++++------------ > > 1 file changed, 4 insertions(+), 12 deletions(-) > > > > diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c > > index b9fb61a..5a183d1 100644 > > --- a/drivers/scsi/scsi_sysfs.c > > +++ b/drivers/scsi/scsi_sysfs.c > > @@ -1158,32 +1158,24 @@ static void __scsi_remove_target(struct scsi_target *starget) > > void scsi_remove_target(struct device *dev) > > { > > struct Scsi_Host *shost = dev_to_shost(dev->parent); > > - struct scsi_target *starget, *last = NULL; > > + struct scsi_target *starget; > > unsigned long flags; > > > > - /* remove targets being careful to lookup next entry before > > - * deleting the last > > - */ > > +restart: > > spin_lock_irqsave(shost->host_lock, flags); > > list_for_each_entry(starget, &shost->__targets, siblings) { > > if (starget->reaped) > > continue; > > if (starget->dev.parent == dev || &starget->dev == dev) { > > - /* assuming new targets arrive at the end */ > > kref_get(&starget->reap_ref); > > starget->reaped = true; > > spin_unlock_irqrestore(shost->host_lock, flags); > > - if (last) > > - scsi_target_reap(last); > > - last = starget; > > __scsi_remove_target(starget); > > - spin_lock_irqsave(shost->host_lock, flags); > > + scsi_target_reap(starget); > > + goto restart; > > } > > } > > spin_unlock_irqrestore(shost->host_lock, flags); > > - > > - if (last) > > - scsi_target_reap(last); > > } > > EXPORT_SYMBOL(scsi_remove_target); > > (replying to my own e-mail) > > Hello Christoph, > > Is it OK for you if I mention you as author of this e-mail ? Could you just both co-operate, especially since there's not much difference between the patches. The fundamental problem with this is how have the conditions that caused us to move away from list restart: commit bc3f02a795d3b4faa99d37390174be2a75d091bd Author: Dan Williams <djbw@xxxxxx> Date: Tue Aug 28 22:12:10 2012 -0700 [SCSI] scsi_remove_target: fix softlockup regression on hot remove Which was triggered by this bug report http://thread.gmane.org/gmane.linux.kernel/1348679 been mitigated? James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
