From: Mike Christie <mchristi@redhat.com>
To: Josef Bacik <josef@toxicpanda.com>
Cc: xiubli@redhat.com, axboe@kernel.dk, linux-block@vger.kernel.org
Subject: Re: [PATCH v4 2/2] nbd: fix possible page fault for nbd disk
Date: Tue, 17 Sep 2019 14:44:09 -0500 [thread overview]
Message-ID: <5D813789.1050400@redhat.com> (raw)
In-Reply-To: <20190917184011.74ityetkw7n3sqbs@MacBook-Pro-91.local>
On 09/17/2019 01:40 PM, Josef Bacik wrote:
>>> + nbd->destroy_complete = &destroy_complete;
>>
>> Also, without the mutex part of the v3 patch, we could race and
>> nbd_dev_remove could have passed the destroy_complete check already, so
>> below we will wait forever.
>>
>
> Oh hmm you're right,
I think I am actually wrong about that part too now :) I had forgot
about the idr removal under the mutex when making my original comment.
If nbd_put grabs the mutex first then it will do idr_remove under the
mutex. If nbd_genl_connect then runs, idr_find/idr_for_each will fail
and we will allocate a new nbd device and NBD_DISCONNECT_REQUESTED will
not be set.
If nbd_genl_connect grabs the mutex first, then idr_find/idr_for_each
will succeed and we will set the completion. nbd_put will then grab the
mutex and call nbd_remove_dev and see the completion.
next prev parent reply other threads:[~2019-09-17 19:44 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-17 11:56 [PATCH v4 0/2] nbd: fix possible page fault for nbd disk xiubli
2019-09-17 11:56 ` [PATCH v4 1/2] nbd: rename the runtime flags as NBD_RT_ prefixed xiubli
2019-09-17 11:56 ` [PATCH v4 2/2] nbd: fix possible page fault for nbd disk xiubli
2019-09-17 18:31 ` Mike Christie
2019-09-17 18:40 ` Josef Bacik
2019-09-17 19:36 ` Mike Christie
2019-09-17 19:44 ` Mike Christie [this message]
2019-09-17 19:56 ` Josef Bacik
2019-09-17 18:15 ` [PATCH v4 0/2] " Josef Bacik
2019-09-17 20:52 ` Jens Axboe
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