netdev - [RFC / RFT net 7/7] tls: rx: strp: don't use GFP

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Date: Wed, 10 May 2023 18:20:34 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: tariqt@...dia.com
Cc: netdev@...r.kernel.org,
	Jakub Kicinski <kuba@...nel.org>
Subject: [RFC / RFT net 7/7] tls: rx: strp: don't use GFP_KERNEL in softirq context

When receive buffer is small, or the TCP rx queue looks too
complicated to bother using it directly - we allocate a new
skb and copy data into it.

We already use sk->sk_allocation... but nothing actually
sets it to GFP_ATOMIC on the ->sk_data_ready() path.

Users of HW offload are far more likely to experience problems
due to scheduling while atomic. "Copy mode" is very rarely
triggered with SW crypto.

Fixes: 84c61fe1a75b ("tls: rx: do not use the standard strparser")
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
 net/tls/tls_sw.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 635b8bf6b937..6e6a7c37d685 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -2304,10 +2304,14 @@ static void tls_data_ready(struct sock *sk)
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct tls_sw_context_rx *ctx = tls_sw_ctx_rx(tls_ctx);
 	struct sk_psock *psock;
+	gfp_t alloc_save;
 
 	trace_sk_data_ready(sk);
 
+	alloc_save = sk->sk_allocation;
+	sk->sk_allocation = GFP_ATOMIC;
 	tls_strp_data_ready(&ctx->strp);
+	sk->sk_allocation = alloc_save;
 
 	psock = sk_psock_get(sk);
 	if (psock) {
-- 
2.40.1