Messages in this thread | | | From | Kuniyuki Iwashima <> | Subject | Re: [PATCH net] net: Remove redundant calls of sk_tx_queue_clear(). | Date | Thu, 28 Jan 2021 01:52:46 +0900 |
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From: Eric Dumazet <edumazet@google.com> Date: Wed, 27 Jan 2021 15:54:32 +0100 > On Wed, Jan 27, 2021 at 1:50 PM Kuniyuki Iwashima <kuniyu@amazon.co.jp> wrote: > > > > The commit 41b14fb8724d ("net: Do not clear the sock TX queue in > > sk_set_socket()") removes sk_tx_queue_clear() from sk_set_socket() and adds > > it instead in sk_alloc() and sk_clone_lock() to fix an issue introduced in > > the commit e022f0b4a03f ("net: Introduce sk_tx_queue_mapping"). However, > > the original commit had already put sk_tx_queue_clear() in sk_prot_alloc(): > > the callee of sk_alloc() and sk_clone_lock(). Thus sk_tx_queue_clear() is > > called twice in each path currently. > > Are you sure ? > > I do not clearly see the sk_tx_queue_clear() call from the cloning part. > > Please elaborate.
If sk is not NULL in sk_prot_alloc(), sk_tx_queue_clear() is called [1]. Also the callers of sk_prot_alloc() are only sk_alloc() and sk_clone_lock(). If they finally return not NULL pointer, sk_tx_queue_clear() is called in each function [2][3].
In the cloning part, sock_copy() is called after sk_prot_alloc(), but skc_tx_queue_mapping is defined between skc_dontcopy_begin and skc_dontcopy_end in struct sock_common [4]. So, sock_copy() does not overwrite skc_tx_queue_mapping, and thus we can initialize it in sk_prot_alloc().
[1] sk_prot_alloc https://github.com/torvalds/linux/blob/master/net/core/sock.c#L1693
[2] sk_alloc https://github.com/torvalds/linux/blob/master/net/core/sock.c#L1762
[3] sk_clone_lock https://github.com/torvalds/linux/blob/master/net/core/sock.c#L1986
[4] struct sock_common https://github.com/torvalds/linux/blob/master/include/net/sock.h#L218-L240
> In any case, this seems to be a candidate for net-next, this is not > fixing a bug, > this would be an optimization at most, and potentially adding a bug. > > So if you resend this patch, you can mention the old commit in the changelog, > but do not add a dubious Fixes: tag
I see.
I will remove the tag and resend this as a net-next candidate.
Thank you, Kuniyuki
> > > > This patch removes the redundant calls of sk_tx_queue_clear() in sk_alloc() > > and sk_clone_lock(). > > > > Fixes: 41b14fb8724d ("net: Do not clear the sock TX queue in sk_set_socket()") > > CC: Tariq Toukan <tariqt@mellanox.com> > > CC: Boris Pismenny <borisp@mellanox.com> > > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp> > > Reviewed-by: Amit Shah <aams@amazon.de> > > --- > > net/core/sock.c | 2 -- > > 1 file changed, 2 deletions(-) > > > > diff --git a/net/core/sock.c b/net/core/sock.c > > index bbcd4b97eddd..5c665ee14159 100644 > > --- a/net/core/sock.c > > +++ b/net/core/sock.c > > @@ -1759,7 +1759,6 @@ struct sock *sk_alloc(struct net *net, int family, gfp_t priority, > > cgroup_sk_alloc(&sk->sk_cgrp_data); > > sock_update_classid(&sk->sk_cgrp_data); > > sock_update_netprioidx(&sk->sk_cgrp_data); > > - sk_tx_queue_clear(sk); > > } > > > > return sk; > > @@ -1983,7 +1982,6 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority) > > */ > > sk_refcnt_debug_inc(newsk); > > sk_set_socket(newsk, NULL); > > - sk_tx_queue_clear(newsk); > > RCU_INIT_POINTER(newsk->sk_wq, NULL); > > > > if (newsk->sk_prot->sockets_allocated) > > -- > > 2.17.2 (Apple Git-113) > >
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