linux-kernel - Re: [PATCH v3] net: xfrm: Add '_rcu' tag for rcu protected pointer in netns

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Date:   Tue, 19 Mar 2019 16:15:03 +0100
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
CC:     Su Yanjun <suyj.fnst@...fujitsu.com>, <davem@...emloft.net>,
        <fw@...len.de>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] net: xfrm: Add '_rcu' tag for rcu protected pointer
 in netns_xfrm

On Mon, Mar 18, 2019 at 10:22:46AM -0700, Eric Dumazet wrote:
> 
> 
> On 03/11/2019 03:10 AM, Steffen Klassert wrote:
> > On Wed, Mar 06, 2019 at 08:54:08PM -0500, Su Yanjun wrote:
> >> For rcu protected pointers, we'd better add '__rcu' for them.
> >>
> >> Once added '__rcu' tag for rcu protected pointer, the sparse tool reports
> >> warnings.
> >>
> >> net/xfrm/xfrm_user.c:1198:39: sparse:    expected struct sock *sk
> >> net/xfrm/xfrm_user.c:1198:39: sparse:    got struct sock [noderef] <asn:4> *nlsk
> >> [...]
> >>
> >> So introduce a new wrapper function of nlmsg_unicast  to handle type
> >> conversions.
> >>
> >> This patch also fixes a direct access of a rcu protected socket.
> >>
> >> Fixes: be33690d8fcf("[XFRM]: Fix aevent related crash")
> >> Signed-off-by: Su Yanjun <suyj.fnst@...fujitsu.com>
> > 
> > Patch applied, thanks!
> > 
> 
> Has this patch ever been tested ?

I had this on your testing system and it did
not complain. But maybe my testcases did not
trigger that codepath. Su, can you answer
on Eric question?