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 ? Thanks, Bart. -- 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
