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Message-Id: <20221107090940.686229-1-nashuiliang@gmail.com>
Date: Mon, 7 Nov 2022 17:09:40 +0800
From: Chuang Wang <nashuiliang@...il.com>
To: unlisted-recipients:; (no To-header on input)
Cc: Chuang Wang <nashuiliang@...il.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v1] 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>
---
v0 -> v1:
- rename tags
drivers/net/tun.c | 68 ++++++++++++++++++++++-------------------------
1 file changed, 32 insertions(+), 36 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 4bf2b268df4a..5ceec73baf98 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1742,11 +1742,11 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
int good_linear;
int copylen;
bool zerocopy = false;
- int err;
+ int err = 0;
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))
@@ -1808,11 +1808,11 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
*/
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(skb);
+ goto drop;
}
if (!skb)
- return total_len;
+ goto out;
} else {
if (!zerocopy) {
copylen = len;
@@ -1836,11 +1836,8 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
}
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(skb);
+ goto drop;
}
if (zerocopy)
@@ -1851,27 +1848,14 @@ 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 drop;
}
switch (tun->flags & TUN_TYPE_MASK) {
@@ -1887,9 +1871,9 @@ 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;
+ drop_reason = SKB_DROP_REASON_INVALID_PROTO;
+ goto drop;
}
}
@@ -1931,11 +1915,7 @@ 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();
@@ -1952,8 +1932,8 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
rcu_read_lock();
if (unlikely(!(tun->dev->flags & IFF_UP))) {
- err = -EIO;
rcu_read_unlock();
+ err = -EIO;
drop_reason = SKB_DROP_REASON_DEV_READY;
goto drop;
}
@@ -2007,7 +1987,23 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
if (rxhash)
tun_flow_update(tun, rxhash, tfile);
- return total_len;
+ goto out;
+
+drop:
+ if (err != -EAGAIN)
+ dev_core_stats_rx_dropped_inc(tun->dev);
+
+ 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);
+ }
+
+out:
+ 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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