From: Bart Van Assche <Bart.VanAssche@sandisk.com>
To: "hch@lst.de" <hch@lst.de>
Cc: "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"James.Bottomley@HansenPartnership.com"
<James.Bottomley@HansenPartnership.com>,
"hare@suse.com" <hare@suse.com>,
"jthumshirn@suse.de" <jthumshirn@suse.de>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>
Subject: Re: [PATCH v3 04/12] Protect SCSI device state changes with a mutex
Date: Mon, 5 Jun 2017 15:18:49 +0000 [thread overview]
Message-ID: <1496675927.2623.1.camel@sandisk.com> (raw)
In-Reply-To: <20170605080937.GB22028@lst.de>
On Mon, 2017-06-05 at 10:09 +0200, Christoph Hellwig wrote:
> On Fri, Jun 02, 2017 at 02:21:55PM -0700, Bart Van Assche wrote:
> > Serializing SCSI device state changes avoids that two state changes
> > can occur concurrently, e.g. the state changes in scsi_target_block()
> > and __scsi_remove_device(). This serialization is essential to make
> > patch "Make __scsi_remove_device go straight from BLOCKED to DEL"
> > work reliably.
> >
> > Enable this mechanism for all scsi_target_*block() callers but not
> > for the scsi_internal_device_unblock() calls from the mpt3sas driver
> > because that driver can call scsi_internal_device_unblock() from
> > atomic context.
>
> And not taking the lock in that path is safe because of what conditions?
Hello Christoph,
The mpt3sas driver is the only driver that calls scsi_internal_device_block()
and scsi_internal_device_unblock() from atomic context. Since it's not an option
to protect the SCSI device state changes with a spinlock I prefer that the
mpt3sas authors convert the scsi_internal_device_block() calls into
scsi_target_block() calls.
Bart.
next prev parent reply other threads:[~2017-06-05 15:20 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-02 21:21 [PATCH v3 00/12] SCSI patches for kernel v4.13 Bart Van Assche
2017-06-02 21:21 ` [PATCH v3 01/12] Avoid that scsi_exit_rq() triggers a use-after-free Bart Van Assche
2017-06-02 21:21 ` Bart Van Assche
2017-06-02 21:21 ` [PATCH v3 02/12] Split scsi_internal_device_block() Bart Van Assche
2017-06-02 21:21 ` [PATCH v3 03/12] Create two versions of scsi_internal_device_unblock() Bart Van Assche
2017-06-02 21:21 ` [PATCH v3 04/12] Protect SCSI device state changes with a mutex Bart Van Assche
2017-06-05 8:09 ` Christoph Hellwig
2017-06-05 15:18 ` Bart Van Assche [this message]
2017-06-05 18:36 ` Bart Van Assche
2017-06-08 15:53 ` hch
2017-06-02 21:21 ` [PATCH v3 05/12] Introduce scsi_start_queue() Bart Van Assche
2017-06-02 21:21 ` [PATCH v3 06/12] Make __scsi_remove_device go straight from BLOCKED to DEL Bart Van Assche
2017-06-02 21:21 ` [PATCH v3 07/12] Only add commands to the device command list if required by the LLD Bart Van Assche
2017-06-02 21:21 ` [PATCH v3 08/12] Introduce scsi_mq_sgl_size() Bart Van Assche
2017-06-02 21:22 ` [PATCH v3 09/12] Make scsi_mq_prep_fn() call scsi_init_command() Bart Van Assche
2017-06-05 8:10 ` Christoph Hellwig
2017-06-02 21:22 ` [PATCH v3 10/12] snic: Remove code that zeroes driver-private command data Bart Van Assche
2017-06-02 21:22 ` [PATCH v3 11/12] virtio_scsi: " Bart Van Assche
2017-06-02 21:22 ` [PATCH v3 12/12] xen/scsifront: " Bart Van Assche
2017-06-02 21:22 ` Bart Van Assche
2017-06-13 1:04 ` [PATCH v3 00/12] SCSI patches for kernel v4.13 Martin K. Petersen
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