From: Ming Lei <ming.lei@redhat.com>
To: Bart Van Assche <Bart.VanAssche@wdc.com>
Cc: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"hch@infradead.org" <hch@infradead.org>,
"snitzer@redhat.com" <snitzer@redhat.com>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"jejb@linux.vnet.ibm.com" <jejb@linux.vnet.ibm.com>,
"loberman@redhat.com" <loberman@redhat.com>,
"dm-devel@redhat.com" <dm-devel@redhat.com>
Subject: Re: [PATCH 1/5] blk-mq: introduce BLK_STS_DEV_RESOURCE
Date: Wed, 24 Jan 2018 00:49:52 +0800 [thread overview]
Message-ID: <20180123164951.GG13277@ming.t460p> (raw)
In-Reply-To: <1516726030.3339.14.camel@wdc.com>
On Tue, Jan 23, 2018 at 04:47:11PM +0000, Bart Van Assche wrote:
> On Wed, 2018-01-24 at 00:41 +0800, Ming Lei wrote:
> > Could you explain where to call call_rcu()? call_rcu() can't be used in
> > IO path at all.
>
> Can you explain what makes you think that call_rcu() can't be used in the
> I/O path? As you know call_rcu() invokes a function asynchronously. From
> Documentation/RCU/Design/Requirements/Requirements.html:
>
> The <tt>call_rcu()</tt> function may be used in a number of
> situations where neither <tt>synchronize_rcu()</tt> nor
> <tt>synchronize_rcu_expedited()</tt> would be legal,
> including within preempt-disable code, <tt>local_bh_disable()</tt> code,
> interrupt-disable code, and interrupt handlers.
OK, suppose it is true, do you want to change most of STS_RESOURCE in
all drivers to this way? Why can't we use the generic and simple approach
in this patch?
--
Ming
next prev parent reply other threads:[~2018-01-23 16:49 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-22 3:35 [PATCH 0/5] blk-mq & dm: fix IO hang and deal with one performance issue Ming Lei
2018-01-22 3:35 ` [PATCH 1/5] blk-mq: introduce BLK_STS_DEV_RESOURCE Ming Lei
2018-01-22 16:32 ` Christoph Hellwig
2018-01-22 16:49 ` Bart Van Assche
2018-01-22 16:49 ` Bart Van Assche
2018-01-23 0:57 ` Ming Lei
2018-01-23 16:17 ` Bart Van Assche
2018-01-23 16:26 ` Ming Lei
2018-01-23 16:37 ` Bart Van Assche
2018-01-23 16:41 ` Ming Lei
2018-01-23 16:47 ` Bart Van Assche
2018-01-23 16:47 ` Bart Van Assche
2018-01-23 16:49 ` Ming Lei [this message]
2018-01-23 16:54 ` Bart Van Assche
2018-01-23 16:54 ` Bart Van Assche
2018-01-23 16:59 ` Ming Lei
2018-01-23 16:59 ` Ming Lei
2018-01-23 22:01 ` Bart Van Assche
2018-01-23 22:01 ` Bart Van Assche
2018-01-24 2:31 ` Ming Lei
2018-01-22 3:35 ` [PATCH 2/5] dm-rq: handle dispatch exception in dm_dispatch_clone_request() Ming Lei
2018-01-22 3:35 ` Ming Lei
2018-01-22 3:35 ` [PATCH 3/5] dm-rq: return BLK_STS_* from map_request() Ming Lei
2018-01-22 3:35 ` Ming Lei
2018-01-22 5:35 ` Ming Lei
2018-01-22 3:35 ` [PATCH 4/5] blk-mq: introduce blk_get_request_notify Ming Lei
2018-01-22 10:19 ` Ming Lei
2018-01-22 17:13 ` Bart Van Assche
2018-01-22 17:13 ` Bart Van Assche
2018-01-23 1:29 ` Ming Lei
2018-01-22 3:35 ` [PATCH 5/5] dm-mpath: use blk_mq_alloc_request_notify for allocating blk-mq req Ming Lei
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