From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "hch@lst.de" <hch@lst.de>
Cc: "jejb@linux.vnet.ibm.com" <jejb@linux.vnet.ibm.com>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"hare@suse.de" <hare@suse.de>,
"jthumshirn@suse.de" <jthumshirn@suse.de>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"shane.seymour@hpe.com" <shane.seymour@hpe.com>
Subject: Re: [PATCH 07/19] Fix RCU handling of scsi_device.vpd_pg8[03]
Date: Thu, 24 Aug 2017 16:54:12 +0000 [thread overview]
Message-ID: <1503593651.2702.16.camel@wdc.com> (raw)
In-Reply-To: <20170824090718.GG19886@lst.de>
On Thu, 2017-08-24 at 11:07 +0200, Christoph Hellwig wrote:
> On Wed, Aug 23, 2017 at 02:39:57PM -0700, Bart Van Assche wrote:
> > Only annotate pointers that are shared across threads with __rcu.
> > Use rcu_dereference() when dereferencing an RCU pointer. Protect
> > also the RCU pointer dereferences when freeing RCU pointers. This
> > patch suppresses about twenty sparse complaints about the vpd_pg8[03]
> > pointers.
>
> Shouldn't the kfrees be kfree_rcu? or where else is the rcu protection
> for them?
Hello Christoph,
My understanding of the SCSI VPD code is as follows:
* rcu_read_lock() / rcu_read_unlock() is used to prevent that another thread
updates a VPD buffer while it is being read.
* All code that either updates or reads a VPD buffer holds a reference on
the SCSI device that buffer is associated with. That is why I think it is
not needed to use kfree_rcu() in scsi_device_dev_release_usercontext().
Bart.
next prev parent reply other threads:[~2017-08-24 16:54 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-23 21:39 [PATCH 00/19] SCSI patches for kernel v4.14 Bart Van Assche
2017-08-23 21:39 ` [PATCH 01/19] Remove an obsolete function declaration Bart Van Assche
2017-08-24 9:02 ` Christoph Hellwig
2017-08-23 21:39 ` [PATCH 02/19] Avoid sign extension of scsi_device.type Bart Van Assche
2017-08-24 6:10 ` Hannes Reinecke
2017-08-24 9:02 ` Christoph Hellwig
2017-08-23 21:39 ` [PATCH 03/19] Suppress gcc 7 fall-through warnings reported with W=1 Bart Van Assche
2017-08-24 9:03 ` Christoph Hellwig
2017-08-23 21:39 ` [PATCH 04/19] Convert a strncmp() call into a strcmp() call Bart Van Assche
2017-08-24 9:03 ` Christoph Hellwig
2017-08-25 15:43 ` Hannes Reinecke
2017-08-23 21:39 ` [PATCH 05/19] scsi_setup_fs_cmnd(): Call scsi_req_init() instead of open-coding it Bart Van Assche
2017-08-24 9:05 ` Christoph Hellwig
2017-08-24 16:17 ` Bart Van Assche
2017-08-23 21:39 ` [PATCH 06/19] Document which queue type a function is intended for Bart Van Assche
2017-08-24 9:05 ` Christoph Hellwig
2017-08-24 16:57 ` Bart Van Assche
2017-08-24 16:58 ` hch
2017-08-24 17:22 ` Bart Van Assche
2017-08-25 15:44 ` Hannes Reinecke
2017-08-23 21:39 ` [PATCH 07/19] Fix RCU handling of scsi_device.vpd_pg8[03] Bart Van Assche
2017-08-24 9:07 ` Christoph Hellwig
2017-08-24 16:54 ` Bart Van Assche [this message]
2017-08-25 5:58 ` Seymour, Shane M
2017-08-25 6:59 ` hch
2017-08-25 20:04 ` Bart Van Assche
2017-08-28 2:02 ` Seymour, Shane M
2017-08-25 15:49 ` Hannes Reinecke
2017-08-25 16:26 ` Bart Van Assche
2017-08-23 21:39 ` [PATCH 08/19] Use blk_mq_rq_to_pdu() to convert a request to a SCSI command pointer Bart Van Assche
2017-08-24 9:07 ` Christoph Hellwig
2017-08-23 21:39 ` [PATCH 09/19] sd, sr: Convert two assignments into warning statements Bart Van Assche
2017-08-24 9:08 ` Christoph Hellwig
2017-08-23 21:40 ` [PATCH 10/19] sd: Fix indentation Bart Van Assche
2017-08-24 9:08 ` Christoph Hellwig
2017-08-25 15:50 ` Hannes Reinecke
2017-08-23 21:40 ` [PATCH 11/19] sd: Remove a useless comparison Bart Van Assche
2017-08-25 15:50 ` Hannes Reinecke
2017-08-23 21:40 ` [PATCH 12/19] sg: Fix type of last blk_trace_setup() argument Bart Van Assche
2017-08-24 9:08 ` Christoph Hellwig
2017-08-25 15:51 ` Hannes Reinecke
2017-08-23 21:40 ` [PATCH 13/19] libiscsi: Fix indentation Bart Van Assche
2017-08-24 9:08 ` Christoph Hellwig
2017-08-25 15:51 ` Hannes Reinecke
2017-08-23 21:40 ` [PATCH 14/19] libsas: Remove a set-but-not-used variable Bart Van Assche
2017-08-24 9:09 ` Christoph Hellwig
2017-08-25 15:51 ` Hannes Reinecke
2017-08-23 21:40 ` [PATCH 15/19] libsas: Annotate fall-through in a switch statement Bart Van Assche
2017-08-24 9:09 ` Christoph Hellwig
2017-08-25 15:52 ` Hannes Reinecke
2017-08-23 21:40 ` [PATCH 16/19] scsi_transport_sas, sas_tlr_supported(): Check kzalloc() return value Bart Van Assche
2017-08-24 9:09 ` Christoph Hellwig
2017-08-25 15:52 ` Hannes Reinecke
2017-08-23 21:40 ` [PATCH 17/19] scsi_transport_srp: Suppress a W=1 compiler warning Bart Van Assche
2017-08-24 9:11 ` Christoph Hellwig
2017-08-24 16:27 ` Bart Van Assche
2017-08-25 15:29 ` hch
2017-08-25 15:40 ` Bart Van Assche
2017-08-25 15:56 ` hch
2017-08-23 21:40 ` [PATCH 18/19] scsi_debug: Remove a set-but-not-used variable Bart Van Assche
2017-08-24 9:12 ` Christoph Hellwig
2017-08-25 15:53 ` Hannes Reinecke
2017-08-23 21:40 ` [PATCH 19/19] iscsi_tcp: " Bart Van Assche
2017-08-24 9:12 ` Christoph Hellwig
2017-08-25 15:53 ` Hannes Reinecke
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