All of lore.kernel.org
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>,
	"dledford@redhat.com" <dledford@redhat.com>,
	"swise@opengridcomputing.com" <swise@opengridcomputing.com>,
	"sagi@grimberg.me" <sagi@grimberg.me>,
	"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
	"target-devel@vger.kernel.org" <target-devel@vger.kernel.org>
Subject: Re: generic RDMA READ/WRITE API V6
Date: Tue, 3 May 2016 10:40:13 +0200	[thread overview]
Message-ID: <20160503084013.GA18906@lst.de> (raw)
In-Reply-To: <5727D14A.8040600@sandisk.com>

On Mon, May 02, 2016 at 03:14:34PM -0700, Bart Van Assche wrote:
> I just noticed that ib_comp_wq is created as follows:
>
> 	ib_comp_wq = alloc_workqueue("ib-comp-wq",
> 			WQ_UNBOUND | WQ_HIGHPRI | WQ_MEM_RECLAIM,
> 			WQ_UNBOUND_MAX_ACTIVE);
>
> I think this breaks the locking guarantees for completion handlers. A quote 
> from Documentation/infiniband/core_locking.txt: "The driver must guarantee 
> that only one CQ event handler for a given CQ is running at a time." The 
> ib_srpt driver assumes that completion handler invocations are serialized 
> such that no locking is needed to access wait_list from inside a completion 
> handler.

This should still be the case - the max_active argument to alloc_workqueue
just specified the amount of work_structs that may be exectured on the
workqueue concurrently, but each individual work_struct can only be
excuted once at a time.  See the following paragraph in
Documentation/workqueue.txt:

"Note that the flag WQ_NON_REENTRANT no longer exists as all workqueues
 are now non-reentrant - any work item is guaranteed to be executed by
 at most one worker system-wide at any given time."

  reply	other threads:[~2016-05-03  8:40 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-11 21:32 generic RDMA READ/WRITE API V6 Christoph Hellwig
2016-04-11 21:32 ` [PATCH 02/12] IB/cma: pass the port number to ib_create_qp Christoph Hellwig
     [not found]   ` <1460410360-13104-3-git-send-email-hch-jcswGhMUV9g@public.gmane.org>
2016-04-15 17:55     ` Sagi Grimberg
2016-04-19  3:14   ` Ira Weiny
2016-04-19 17:30     ` Jason Gunthorpe
2016-04-19 18:38       ` Christoph Hellwig
     [not found]         ` <20160419183830.GB1211-jcswGhMUV9g@public.gmane.org>
2016-04-28 21:05           ` Doug Ledford
     [not found]       ` <20160419173032.GD20844-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2016-04-19 18:49         ` Sagi Grimberg
2016-04-19 19:24           ` Jason Gunthorpe
     [not found]             ` <20160419192430.GB27028-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2016-04-19 19:41               ` Steve Wise
2016-04-19 20:05                 ` 'Christoph Hellwig'
2016-04-19 20:21                   ` Jason Gunthorpe
     [not found]                   ` <20160419200555.GA2561-jcswGhMUV9g@public.gmane.org>
2016-04-19 20:26                     ` Steve Wise
2016-04-21  3:11                       ` ira.weiny
2016-04-28 19:43               ` Hefty, Sean
2016-04-28 20:07                 ` Jason Gunthorpe
2016-04-28 21:53                   ` Hefty, Sean
2016-04-28 22:09                     ` Jason Gunthorpe
2016-04-28 23:23                       ` Hefty, Sean
2016-04-28 23:49                         ` Jason Gunthorpe
2016-04-28 23:25                       ` Weiny, Ira
     [not found]                         ` <2807E5FD2F6FDA4886F6618EAC48510E22EC858F-8k97q/ur5Z2krb+BlOpmy7fspsVTdybXVpNB7YpNyf8@public.gmane.org>
2016-04-29  0:01                           ` Jason Gunthorpe
2016-04-11 21:32 ` [PATCH 03/12] IB/core: allow passing mapping an offset into the SG in ib_map_mr_sg Christoph Hellwig
     [not found]   ` <1460410360-13104-4-git-send-email-hch-jcswGhMUV9g@public.gmane.org>
2016-04-15 17:56     ` Sagi Grimberg
2016-04-11 21:32 ` [PATCH 04/12] IB/core: add a helper to check for READ WITH INVALIDATE support Christoph Hellwig
     [not found]   ` <1460410360-13104-5-git-send-email-hch-jcswGhMUV9g@public.gmane.org>
2016-04-15 17:56     ` Sagi Grimberg
2016-04-19  3:15   ` Ira Weiny
2016-04-11 21:32 ` [PATCH 05/12] IB/core: refactor ib_create_qp Christoph Hellwig
2016-04-17 20:00   ` Sagi Grimberg
     [not found]   ` <1460410360-13104-6-git-send-email-hch-jcswGhMUV9g@public.gmane.org>
2016-04-19  3:08     ` Ira Weiny
2016-04-11 21:32 ` [PATCH 07/12] IB/core: add a need_inval flag to struct ib_mr Christoph Hellwig
     [not found]   ` <1460410360-13104-8-git-send-email-hch-jcswGhMUV9g@public.gmane.org>
2016-04-17 20:01     ` Sagi Grimberg
2016-04-19  3:20   ` Ira Weiny
2016-04-11 21:32 ` [PATCH 08/12] IB/core: generic RDMA READ/WRITE API Christoph Hellwig
     [not found]   ` <1460410360-13104-9-git-send-email-hch-jcswGhMUV9g@public.gmane.org>
2016-04-12 23:52     ` Bart Van Assche
     [not found]       ` <570D8A42.9040107-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>
2016-04-13 13:50         ` Christoph Hellwig
     [not found] ` <1460410360-13104-1-git-send-email-hch-jcswGhMUV9g@public.gmane.org>
2016-04-11 21:32   ` [PATCH 01/12] IB/mlx5: Expose correct max_sge_rd limit Christoph Hellwig
     [not found]     ` <1460410360-13104-2-git-send-email-hch-jcswGhMUV9g@public.gmane.org>
2016-04-17 13:53       ` Leon Romanovsky
     [not found]         ` <20160417135341.GC6349-2ukJVAZIZ/Y@public.gmane.org>
2016-04-17 18:06           ` Christoph Hellwig
2016-04-11 21:32   ` [PATCH 06/12] IB/core: add a simple MR pool Christoph Hellwig
2016-04-17 20:01     ` Sagi Grimberg
2016-04-19  3:19     ` Ira Weiny
2016-04-11 21:32   ` [PATCH 09/12] target: enhance and export target_alloc_sgl/target_free_sgl Christoph Hellwig
2016-04-11 21:32 ` [PATCH 10/12] IB/srpt: convert to the generic RDMA READ/WRITE API Christoph Hellwig
2016-04-13 18:57   ` Bart Van Assche
2016-04-14 13:32     ` Christoph Hellwig
2016-04-28 21:02       ` Doug Ledford
     [not found]         ` <57227A6D.4000802-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-04-29  6:34           ` Christoph Hellwig
     [not found]             ` <20160429063443.GA18893-jcswGhMUV9g@public.gmane.org>
2016-04-29 14:44               ` Doug Ledford
2016-04-11 21:32 ` [PATCH 11/12] IB/core: add RW API support for signature MRs Christoph Hellwig
     [not found]   ` <1460410360-13104-12-git-send-email-hch-jcswGhMUV9g@public.gmane.org>
2016-04-22 21:53     ` Bart Van Assche
2016-04-11 21:32 ` [PATCH 12/12] IB/isert: convert to the generic RDMA READ/WRITE API Christoph Hellwig
     [not found]   ` <1460410360-13104-13-git-send-email-hch-jcswGhMUV9g@public.gmane.org>
2016-04-28 21:04     ` Doug Ledford
2016-04-29 11:46       ` Sagi Grimberg
     [not found]         ` <572349AA.2070407-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>
2016-04-29 14:45           ` Doug Ledford
     [not found]             ` <e7959da7-79ca-0422-fbc9-9b3814516e1b-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-04-29 16:42               ` Leon Romanovsky
2016-04-12 18:31 ` generic RDMA READ/WRITE API V6 Steve Wise
2016-04-22 22:29 ` Bart Van Assche
     [not found]   ` <571AA5C8.4080502-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>
2016-05-02 15:15     ` Christoph Hellwig
     [not found]       ` <20160502151535.GA520-jcswGhMUV9g@public.gmane.org>
2016-05-02 19:08         ` Bart Van Assche
2016-05-02 22:14           ` Bart Van Assche
2016-05-03  8:40             ` Christoph Hellwig [this message]
2016-05-03 16:10               ` Bart Van Assche
     [not found]           ` <5727A5C7.1090009-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>
2016-05-03 14:31             ` Christoph Hellwig
     [not found]               ` <20160503143104.GA30342-jcswGhMUV9g@public.gmane.org>
2016-05-03 21:23                 ` Bart Van Assche

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20160503084013.GA18906@lst.de \
    --to=hch@lst.de \
    --cc=bart.vanassche@sandisk.com \
    --cc=dledford@redhat.com \
    --cc=linux-rdma@vger.kernel.org \
    --cc=sagi@grimberg.me \
    --cc=swise@opengridcomputing.com \
    --cc=target-devel@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.