* [PATCH] nbd: fix possible sysfs duplicate warning
@ 2019-09-19 6:14 xiubli
2019-10-10 13:56 ` Josef Bacik
2019-10-10 15:45 ` Jens Axboe
0 siblings, 2 replies; 4+ messages in thread
From: xiubli @ 2019-09-19 6:14 UTC (permalink / raw)
To: josef, axboe; +Cc: mchristi, ming.lei, linux-block, Xiubo Li
From: Xiubo Li <xiubli@redhat.com>
1. nbd_put takes the mutex and drops nbd->ref to 0. It then does
idr_remove and drops the mutex.
2. nbd_genl_connect takes the mutex. idr_find/idr_for_each fails
to find an existing device, so it does nbd_dev_add.
3. just before the nbd_put could call nbd_dev_remove or not finished
totally, but if nbd_dev_add try to add_disk, we can hit:
debugfs: Directory 'nbd1' with parent 'block' already present!
This patch will make sure all the disk add/remove stuff are done
by holding the nbd_index_mutex lock.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reported-by: Mike Christie <mchristi@redhat.com>
---
drivers/block/nbd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index ac07e8c94c79..478aa86fc1f2 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -248,8 +248,8 @@ static void nbd_put(struct nbd_device *nbd)
if (refcount_dec_and_mutex_lock(&nbd->refs,
&nbd_index_mutex)) {
idr_remove(&nbd_index_idr, nbd->index);
- mutex_unlock(&nbd_index_mutex);
nbd_dev_remove(nbd);
+ mutex_unlock(&nbd_index_mutex);
}
}
--
2.21.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] nbd: fix possible sysfs duplicate warning
2019-09-19 6:14 [PATCH] nbd: fix possible sysfs duplicate warning xiubli
@ 2019-10-10 13:56 ` Josef Bacik
2019-10-11 0:39 ` Xiubo Li
2019-10-10 15:45 ` Jens Axboe
1 sibling, 1 reply; 4+ messages in thread
From: Josef Bacik @ 2019-10-10 13:56 UTC (permalink / raw)
To: xiubli; +Cc: josef, axboe, mchristi, ming.lei, linux-block
On Thu, Sep 19, 2019 at 11:44:27AM +0530, xiubli@redhat.com wrote:
> From: Xiubo Li <xiubli@redhat.com>
>
> 1. nbd_put takes the mutex and drops nbd->ref to 0. It then does
> idr_remove and drops the mutex.
>
> 2. nbd_genl_connect takes the mutex. idr_find/idr_for_each fails
> to find an existing device, so it does nbd_dev_add.
>
> 3. just before the nbd_put could call nbd_dev_remove or not finished
> totally, but if nbd_dev_add try to add_disk, we can hit:
>
> debugfs: Directory 'nbd1' with parent 'block' already present!
>
> This patch will make sure all the disk add/remove stuff are done
> by holding the nbd_index_mutex lock.
>
> Signed-off-by: Xiubo Li <xiubli@redhat.com>
> Reported-by: Mike Christie <mchristi@redhat.com>
Sorry, don't know how I missed this.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Thanks,
Josef
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] nbd: fix possible sysfs duplicate warning
2019-10-10 13:56 ` Josef Bacik
@ 2019-10-11 0:39 ` Xiubo Li
0 siblings, 0 replies; 4+ messages in thread
From: Xiubo Li @ 2019-10-11 0:39 UTC (permalink / raw)
To: Josef Bacik; +Cc: axboe, mchristi, ming.lei, linux-block
On 2019/10/10 21:56, Josef Bacik wrote:
> On Thu, Sep 19, 2019 at 11:44:27AM +0530, xiubli@redhat.com wrote:
>> From: Xiubo Li <xiubli@redhat.com>
>>
>> 1. nbd_put takes the mutex and drops nbd->ref to 0. It then does
>> idr_remove and drops the mutex.
>>
>> 2. nbd_genl_connect takes the mutex. idr_find/idr_for_each fails
>> to find an existing device, so it does nbd_dev_add.
>>
>> 3. just before the nbd_put could call nbd_dev_remove or not finished
>> totally, but if nbd_dev_add try to add_disk, we can hit:
>>
>> debugfs: Directory 'nbd1' with parent 'block' already present!
>>
>> This patch will make sure all the disk add/remove stuff are done
>> by holding the nbd_index_mutex lock.
>>
>> Signed-off-by: Xiubo Li <xiubli@redhat.com>
>> Reported-by: Mike Christie <mchristi@redhat.com>
> Sorry, don't know how I missed this.
Many thanks.
Xiubo
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>
>
> Thanks,
>
> Josef
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] nbd: fix possible sysfs duplicate warning
2019-09-19 6:14 [PATCH] nbd: fix possible sysfs duplicate warning xiubli
2019-10-10 13:56 ` Josef Bacik
@ 2019-10-10 15:45 ` Jens Axboe
1 sibling, 0 replies; 4+ messages in thread
From: Jens Axboe @ 2019-10-10 15:45 UTC (permalink / raw)
To: xiubli, josef; +Cc: mchristi, ming.lei, linux-block
On 9/19/19 12:14 AM, xiubli@redhat.com wrote:
> From: Xiubo Li <xiubli@redhat.com>
>
> 1. nbd_put takes the mutex and drops nbd->ref to 0. It then does
> idr_remove and drops the mutex.
>
> 2. nbd_genl_connect takes the mutex. idr_find/idr_for_each fails
> to find an existing device, so it does nbd_dev_add.
>
> 3. just before the nbd_put could call nbd_dev_remove or not finished
> totally, but if nbd_dev_add try to add_disk, we can hit:
>
> debugfs: Directory 'nbd1' with parent 'block' already present!
>
> This patch will make sure all the disk add/remove stuff are done
> by holding the nbd_index_mutex lock.
Applied, thanks.
--
Jens Axboe
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-09-19 6:14 [PATCH] nbd: fix possible sysfs duplicate warning xiubli
2019-10-10 13:56 ` Josef Bacik
2019-10-11 0:39 ` Xiubo Li
2019-10-10 15:45 ` Jens Axboe
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