linux-kernel - Re: [PATCH -next] IB/qib: Add missing err handle for qib_user_sdma_rb

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Message-ID: <cef0e281-1d93-a0cf-03f1-b96622970567@huawei.com>
Date:   Thu, 3 Jan 2019 10:05:25 +0800
From:   YueHaibing <yuehaibing@...wei.com>
To:     Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>
CC:     <dennis.dalessandro@...el.com>, <mike.marciniszyn@...el.com>,
        <dledford@...hat.com>, <linux-kernel@...r.kernel.org>,
        <linux-rdma@...r.kernel.org>
Subject: Re: [PATCH -next] IB/qib: Add missing err handle for
 qib_user_sdma_rb_insert

On 2019/1/3 3:07, Jason Gunthorpe wrote:
> On Wed, Jan 02, 2019 at 08:40:50PM +0200, Leon Romanovsky wrote:
>> On Wed, Jan 02, 2019 at 10:12:24AM -0700, Jason Gunthorpe wrote:
>>> On Fri, Dec 21, 2018 at 10:19:38AM +0800, YueHaibing wrote:
>>>> It should goto err handle if qib_user_sdma_rb_insert fails,
>>>> other than success return.
>>>>
>>>> Fixes: 67810e8c3c01 ("RDMA/qib: Remove all occurrences of BUG_ON()")
>>>> Signed-off-by: YueHaibing <yuehaibing@...wei.com>
>>>>  drivers/infiniband/hw/qib/qib_user_sdma.c | 2 ++
>>>>  1 file changed, 2 insertions(+)
>>>>
>>>> diff --git a/drivers/infiniband/hw/qib/qib_user_sdma.c b/drivers/infiniband/hw/qib/qib_user_sdma.c
>>>> index 31c523b..e87c0a7 100644
>>>> +++ b/drivers/infiniband/hw/qib/qib_user_sdma.c
>>>> @@ -237,6 +237,8 @@ qib_user_sdma_queue_create(struct device *dev, int unit, int ctxt, int sctxt)
>>>>
>>>>  		ret = qib_user_sdma_rb_insert(&qib_user_sdma_rb_root,
>>>>  					sdma_rb_node);
>>>> +		if (ret == 0)
>>>> +			goto err_rb;
>>>>  	}
>>>
>>> This doesn't look right, what about undoing the kmalloc directly
>>> above?
>>
>> Back then, I came to conclusion that qib_user_sdma_rb_insert() never
>> returns 0. Otherwise, Dennis would see that BUG_ON() for a long time
>> ago.
> 
> It fails if the index is in the RB tree, which would indicate a
> programming bug.
> 
> The way to replace the BUG_ON is something like:
> 

Oh, yes,  I forget kfree this mem.

> if (WARN_ON(ret == 0)) {
>     kfree()
>     goto err_rb;
> }
> 
> Jason
> 
> .
>