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Message-Id: <20221110073125.692259-1-nashuiliang@gmail.com>
Date: Thu, 10 Nov 2022 15:31:25 +0800
From: Chuang Wang <nashuiliang@...il.com>
To: unlisted-recipients:; (no To-header on input)
Cc: Chuang Wang <nashuiliang@...il.com>,
Jakub Kicinski <kuba@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2] net: tun: rebuild error handling in tun_get_user
The error handling in tun_get_user is very scattered.
This patch unifies error handling, reduces duplication of code, and
makes the logic clearer.
Signed-off-by: Chuang Wang <nashuiliang@...il.com>
---
v1 -> v2:
- fix problems based on Jakub Kicinski's comments
v0 -> v1:
- rename tags
drivers/net/tun.c | 65 +++++++++++++++++++++--------------------------
1 file changed, 29 insertions(+), 36 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 4bf2b268df4a..27109d1fd187 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1746,7 +1746,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
u32 rxhash = 0;
int skb_xdp = 1;
bool frags = tun_napi_frags_enabled(tfile);
- enum skb_drop_reason drop_reason;
+ enum skb_drop_reason drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
if (!(tun->flags & IFF_NO_PI)) {
if (len < sizeof(pi))
@@ -1807,10 +1807,9 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
* skb was created with generic XDP routine.
*/
skb = tun_build_skb(tun, tfile, from, &gso, len, &skb_xdp);
- if (IS_ERR(skb)) {
- dev_core_stats_rx_dropped_inc(tun->dev);
- return PTR_ERR(skb);
- }
+ err = PTR_ERR_OR_ZERO(skb);
+ if (err)
+ goto drop;
if (!skb)
return total_len;
} else {
@@ -1835,13 +1834,9 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
noblock);
}
- if (IS_ERR(skb)) {
- if (PTR_ERR(skb) != -EAGAIN)
- dev_core_stats_rx_dropped_inc(tun->dev);
- if (frags)
- mutex_unlock(&tfile->napi_mutex);
- return PTR_ERR(skb);
- }
+ err = PTR_ERR_OR_ZERO(skb);
+ if (err)
+ goto drop;
if (zerocopy)
err = zerocopy_sg_from_iter(skb, from);
@@ -1851,27 +1846,14 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
if (err) {
err = -EFAULT;
drop_reason = SKB_DROP_REASON_SKB_UCOPY_FAULT;
-drop:
- dev_core_stats_rx_dropped_inc(tun->dev);
- kfree_skb_reason(skb, drop_reason);
- if (frags) {
- tfile->napi.skb = NULL;
- mutex_unlock(&tfile->napi_mutex);
- }
-
- return err;
+ goto drop;
}
}
if (virtio_net_hdr_to_skb(skb, &gso, tun_is_little_endian(tun))) {
atomic_long_inc(&tun->rx_frame_errors);
- kfree_skb(skb);
- if (frags) {
- tfile->napi.skb = NULL;
- mutex_unlock(&tfile->napi_mutex);
- }
-
- return -EINVAL;
+ err = -EINVAL;
+ goto free_skb;
}
switch (tun->flags & TUN_TYPE_MASK) {
@@ -1887,9 +1869,8 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
pi.proto = htons(ETH_P_IPV6);
break;
default:
- dev_core_stats_rx_dropped_inc(tun->dev);
- kfree_skb(skb);
- return -EINVAL;
+ err = -EINVAL;
+ goto drop;
}
}
@@ -1931,11 +1912,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
if (ret != XDP_PASS) {
rcu_read_unlock();
local_bh_enable();
- if (frags) {
- tfile->napi.skb = NULL;
- mutex_unlock(&tfile->napi_mutex);
- }
- return total_len;
+ goto unlock_frags;
}
}
rcu_read_unlock();
@@ -2008,6 +1985,22 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
tun_flow_update(tun, rxhash, tfile);
return total_len;
+
+drop:
+ if (err != -EAGAIN)
+ dev_core_stats_rx_dropped_inc(tun->dev);
+
+free_skb:
+ if (!IS_ERR_OR_NULL(skb))
+ kfree_skb_reason(skb, drop_reason);
+
+unlock_frags:
+ if (frags) {
+ tfile->napi.skb = NULL;
+ mutex_unlock(&tfile->napi_mutex);
+ }
+
+ return err ?: total_len;
}
static ssize_t tun_chr_write_iter(struct kiocb *iocb, struct iov_iter *from)
--
2.37.2
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