From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: [PATCH v7 1/9] Fix race between starved list processing and device removal Date: Sat, 09 Feb 2013 16:06:39 +0100 Message-ID: <511665FF.8090408@acm.org> References: <50C0BEEE.4040907@acm.org> <50C0BF50.4080009@acm.org> <034101cdee08$2d67f870$8837e950$@min@lge.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from gerard.telenet-ops.be ([195.130.132.48]:58941 "EHLO gerard.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932309Ab3BIPGm (ORCPT ); Sat, 9 Feb 2013 10:06:42 -0500 In-Reply-To: <034101cdee08$2d67f870$8837e950$@min@lge.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: 'James Bottomley' Cc: Chanho Min , 'linux-scsi' Hello James, Please consider this patch for inclusion in kernel 3.9. Thanks, Bart. On 01/09/13 02:25, Chanho Min wrote: > Is there any progress in this patch? > Oops is still occurred from a torn down device due to this cause. > We look forward to this patch is applied to mainline ASAP. > > Thanks > Chanho Min > >> -----Original Message----- >> From: Bart Van Assche [mailto:bvanassche@acm.org] >> Sent: Friday, December 07, 2012 12:53 AM >> To: undisclosed-recipients: >> Cc: linux-scsi; James Bottomley; Mike Christie; Tejun Heo; Chanho Min; Jens Axboe >> Subject: [PATCH v7 1/9] Fix race between starved list processing and device removal >> >> Avoid that the sdev reference count can drop to zero before >> a queue is run by scsi_run_queue(). >> >> Signed-off-by: Bart Van Assche >> Reported-and-tested-by: Chanho Min >> Reference: http://lkml.org/lkml/2012/8/2/96 >> Acked-by: Tejun Heo >> Reviewed-by: Mike Christie >> Cc: Jens Axboe >> Cc: >> --- >> drivers/scsi/scsi_lib.c | 16 +++++++++++----- >> drivers/scsi/scsi_sysfs.c | 14 +++++++++++++- >> 2 files changed, 24 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c >> index f1bf5af..5c67339 100644 >> --- a/drivers/scsi/scsi_lib.c >> +++ b/drivers/scsi/scsi_lib.c >> @@ -452,11 +452,17 @@ static void scsi_run_queue(struct request_queue *q) >> continue; >> } >> >> - spin_unlock(shost->host_lock); >> - spin_lock(sdev->request_queue->queue_lock); >> - __blk_run_queue(sdev->request_queue); >> - spin_unlock(sdev->request_queue->queue_lock); >> - spin_lock(shost->host_lock); >> + /* >> + * Obtain a reference before unlocking the host_lock such that >> + * the sdev can't disappear before blk_run_queue() is invoked. >> + */ >> + get_device(&sdev->sdev_gendev); >> + spin_unlock_irqrestore(shost->host_lock, flags); >> + >> + blk_run_queue(sdev->request_queue); >> + put_device(&sdev->sdev_gendev); >> + >> + spin_lock_irqsave(shost->host_lock, flags); >> } >> /* put any unprocessed entries back */ >> list_splice(&starved_list, &shost->starved_list); >> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c >> index ce5224c..2ff7ba5 100644 >> --- a/drivers/scsi/scsi_sysfs.c >> +++ b/drivers/scsi/scsi_sysfs.c >> @@ -348,7 +348,6 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) >> starget->reap_ref++; >> list_del(&sdev->siblings); >> list_del(&sdev->same_target_siblings); >> - list_del(&sdev->starved_entry); >> spin_unlock_irqrestore(sdev->host->host_lock, flags); >> >> cancel_work_sync(&sdev->event_work); >> @@ -956,6 +955,8 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev) >> void __scsi_remove_device(struct scsi_device *sdev) >> { >> struct device *dev = &sdev->sdev_gendev; >> + struct Scsi_Host *shost = sdev->host; >> + unsigned long flags; >> >> if (sdev->is_visible) { >> if (scsi_device_set_state(sdev, SDEV_CANCEL) != 0) >> @@ -977,6 +978,17 @@ void __scsi_remove_device(struct scsi_device *sdev) >> blk_cleanup_queue(sdev->request_queue); >> cancel_work_sync(&sdev->requeue_work); >> >> + /* >> + * Remove a SCSI device from the starved list after blk_cleanup_queue() >> + * finished such that scsi_request_fn() can't add it back to that list. >> + * Also remove an sdev from the starved list before invoking >> + * put_device() such that get_device() is guaranteed to succeed for an >> + * sdev present on the starved list. >> + */ >> + spin_lock_irqsave(shost->host_lock, flags); >> + list_del(&sdev->starved_entry); >> + spin_unlock_irqrestore(shost->host_lock, flags); >> + >> if (sdev->host->hostt->slave_destroy) >> sdev->host->hostt->slave_destroy(sdev); >> transport_destroy_device(dev); >> -- >> 1.7.10.4 > >