From: Christoph Hellwig <hch@lst.de>
To: Noa Osherovich <noaos@mellanox.com>
Cc: hch@lst.de, sagi@grimberg.me, linux-rdma@vger.kernel.org,
Majd Dibbiny <majd@mellanox.com>,
tj@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Poll CQ syncing problem
Date: Wed, 1 Mar 2017 15:51:24 +0100 [thread overview]
Message-ID: <20170301145124.GA12121@lst.de> (raw)
In-Reply-To: <3ba1baab-e2ac-358d-3b3b-ff4a27405c93@mellanox.com>
On Wed, Mar 01, 2017 at 04:30:26PM +0200, Noa Osherovich wrote:
> Analysis:
> Since ib_comp_wq isn't single threaded, two works can run in parallel for the same CQ,
> executing __ib_process_cq.
They shouldn't. Each CQ has a single work_struct, and any given work_struct
should only be executing at once:
"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."
> Since this function isn't thread safe and the wc array is shared, it causes a data corruption
> which eventually crashes in the MAD layer due to a double list_del of the same element.
This should not be the case. What kernel version are you testing and does
it contain any patches touching core kernel code?
next parent reply other threads:[~2017-03-01 15:07 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <b4355d22-fc79-c860-de8a-5a4d468c884d@mellanox.com>
[not found] ` <3ba1baab-e2ac-358d-3b3b-ff4a27405c93@mellanox.com>
2017-03-01 14:51 ` Christoph Hellwig [this message]
2017-03-01 15:28 ` Poll CQ syncing problem Noa Osherovich
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