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tcp: tcp_check_req() can be called from process context 

This is a follow up of commit 0a375c8224 ("tcp: tcp_rtx_synack()
can be called from process context").

Frederick Lawler reported another "__this_cpu_add() in preemptible"
warning caused by the same reason.

In my former patch I took care of tcp_rtx_synack()
but forgot that tcp_check_req() also contained some SNMP updates.

Note that some parts of tcp_check_req() always run in BH context,
I added a comment to clarify this.

Fixes: 8336886f78 ("tcp: TCP Fast Open Server - support TFO listeners")
Link: https://lore.kernel.org/netdev/8cd33923-a21d-397c-e46b-2a068c287b03@cloudflare.com/T/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Frederick Lawler <fred@cloudflare.com>
Tested-by: Frederick Lawler <fred@cloudflare.com>
Link: https://lore.kernel.org/r/20230227083336.4153089-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2023-02-27 08:33:36 +00:00 committed by Jakub Kicinski
parent 972074ea88
commit 580f98cc33
1 changed files with 5 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
net/ipv4/tcp_minisocks.c
View File

@ -597,6 +597,9 @@ EXPORT_SYMBOL(tcp_create_openreq_child);
* validation and inside tcp_v4_reqsk_send_ack(). Can we do better?
*
* We don't need to initialize tmp_opt.sack_ok as we don't use the results
*
* Note: If @fastopen is true, this can be called from process context.
* Otherwise, this is from BH context.
*/
struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
@ -748,7 +751,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
&tcp_rsk(req)->last_oow_ack_time))
req->rsk_ops->send_ack(sk, skb, req);
if (paws_reject)
__NET_INC_STATS(sock_net(sk), LINUX_MIB_PAWSESTABREJECTED);
NET_INC_STATS(sock_net(sk), LINUX_MIB_PAWSESTABREJECTED);
return NULL;
}
@ -767,7 +770,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
* "fourth, check the SYN bit"
*/
if (flg & (TCP_FLAG_RST|TCP_FLAG_SYN)) {
__TCP_INC_STATS(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
TCP_INC_STATS(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
goto embryonic_reset;
}