Messages in this thread | | | Subject | Re: [PATCH v3 net-next] net: Remove redundant calls of sk_tx_queue_clear(). | From | Tariq Toukan <> | Date | Thu, 28 Jan 2021 13:07:26 +0200 |
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On 1/28/2021 4:19 AM, Kuniyuki Iwashima 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"). On the > other hand, 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. > > If we remove sk_tx_queue_clear() in sk_alloc() and sk_clone_lock(), it > currently works well because (i) sk_tx_queue_mapping is defined between > sk_dontcopy_begin and sk_dontcopy_end, and (ii) sock_copy() called after > sk_prot_alloc() in sk_clone_lock() does not overwrite sk_tx_queue_mapping. > However, if we move sk_tx_queue_mapping out of the no copy area, it > introduces a bug unintentionally. > > Therefore, this patch adds a runtime
compile-time
> check to take care of the order of > sock_copy() and sk_tx_queue_clear() and removes sk_tx_queue_clear() from > sk_prot_alloc() so that it does the only allocation and its callers > initialize fields. > > v3: > * Remove Fixes: tag > * Add BUILD_BUG_ON > * Remove sk_tx_queue_clear() from sk_prot_alloc() > instead of sk_alloc() and sk_clone_lock() > > v2: https://lore.kernel.org/netdev/20210127132215.10842-1-kuniyu@amazon.co.jp/ > * Remove Reviewed-by: tag > > v1: https://lore.kernel.org/netdev/20210127125018.7059-1-kuniyu@amazon.co.jp/ > > CC: Tariq Toukan <tariqt@mellanox.com> > CC: Boris Pismenny <borisp@mellanox.com> > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp> > --- > net/core/sock.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/net/core/sock.c b/net/core/sock.c > index bbcd4b97eddd..cfbd62a5e079 100644 > --- a/net/core/sock.c > +++ b/net/core/sock.c > @@ -1657,6 +1657,16 @@ static void sock_copy(struct sock *nsk, const struct sock *osk) > #ifdef CONFIG_SECURITY_NETWORK > void *sptr = nsk->sk_security; > #endif > + > + /* If we move sk_tx_queue_mapping out of the private section, > + * we must check if sk_tx_queue_clear() is called after > + * sock_copy() in sk_clone_lock(). > + */ > + BUILD_BUG_ON(offsetof(struct sock, sk_tx_queue_mapping) < > + offsetof(struct sock, sk_dontcopy_begin) || > + offsetof(struct sock, sk_tx_queue_mapping) >= > + offsetof(struct sock, sk_dontcopy_end)); > + > memcpy(nsk, osk, offsetof(struct sock, sk_dontcopy_begin)); > > memcpy(&nsk->sk_dontcopy_end, &osk->sk_dontcopy_end, > @@ -1690,7 +1700,6 @@ static struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority, > > if (!try_module_get(prot->owner)) > goto out_free_sec; > - sk_tx_queue_clear(sk); > } > > return sk; >
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