From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: [PATCH] scsi: restart list search after unlock in scsi_remove_target Date: Mon, 19 Oct 2015 16:35:46 +0200 Message-ID: <20151019143546.GA7486@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from verein.lst.de ([213.95.11.211]:53904 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750814AbbJSOfu (ORCPT ); Mon, 19 Oct 2015 10:35:50 -0400 Content-Disposition: inline Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: linux-scsi@vger.kernel.org, James.Bottomley@HansenPartnership.com Cc: jthumshirn@suse.de 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. Reported-by: Johannes Thumshirn Signed-off-by: Christoph Hellwig diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index b333389f..d3b34d8 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -1158,31 +1158,23 @@ 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->state == STARGET_DEL) continue; if (starget->dev.parent == dev || &starget->dev == dev) { - /* assuming new targets arrive at the end */ kref_get(&starget->reap_ref); 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);