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kernel: backport fix for hang on napi_disable with threaded NAPI

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Signed-off-by: Felix Fietkau <nbd@nbd.name>
This commit is contained in:
Felix Fietkau 2021-06-01 23:19:48 +02:00
parent 507257778c
commit 9bda91d805
2 changed files with 57 additions and 4 deletions
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53
target/linux/generic/backport-5.10/604-v5.12-net-fix-hangup-on-napi_disable-for-threaded-napi.patch Normal file
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@ -0,0 +1,53 @@
From: Paolo Abeni <pabeni@redhat.com>
Date: Fri, 9 Apr 2021 17:24:17 +0200
Subject: [PATCH] net: fix hangup on napi_disable for threaded napi
napi_disable() is subject to an hangup, when the threaded
mode is enabled and the napi is under heavy traffic.
If the relevant napi has been scheduled and the napi_disable()
kicks in before the next napi_threaded_wait() completes - so
that the latter quits due to the napi_disable_pending() condition,
the existing code leaves the NAPI_STATE_SCHED bit set and the
napi_disable() loop waiting for such bit will hang.
This patch addresses the issue by dropping the NAPI_STATE_DISABLE
bit test in napi_thread_wait(). The later napi_threaded_poll()
iteration will take care of clearing the NAPI_STATE_SCHED.
This also addresses a related problem reported by Jakub:
before this patch a napi_disable()/napi_enable() pair killed
the napi thread, effectively disabling the threaded mode.
On the patched kernel napi_disable() simply stops scheduling
the relevant thread.
v1 -> v2:
- let the main napi_thread_poll() loop clear the SCHED bit
Reported-by: Jakub Kicinski <kuba@kernel.org>
Fixes: 29863d41bb6e ("net: implement threaded-able napi poll loop support")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/883923fa22745a9589e8610962b7dc59df09fb1f.1617981844.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6951,7 +6951,7 @@ static int napi_thread_wait(struct napi_
set_current_state(TASK_INTERRUPTIBLE);
- while (!kthread_should_stop() && !napi_disable_pending(napi)) {
+ while (!kthread_should_stop()) {
/* Testing SCHED_THREADED bit here to make sure the current
* kthread owns this napi and could poll on this napi.
* Testing SCHED bit is not enough because SCHED bit might be
@@ -6969,6 +6969,7 @@ static int napi_thread_wait(struct napi_
set_current_state(TASK_INTERRUPTIBLE);
}
__set_current_state(TASK_RUNNING);
+
return -1;
}

8
target/linux/generic/pending-5.10/680-NET-skip-GRO-for-foreign-MAC-addresses.patch
View File

@ -42,7 +42,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
if (netif_elide_gro(skb->dev))
goto normal;
@@ -7986,6 +7989,48 @@ static void __netdev_adjacent_dev_unlink
@@ -7987,6 +7990,48 @@ static void __netdev_adjacent_dev_unlink
&upper_dev->adj_list.lower);
}
@ -91,7 +91,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
static int __netdev_upper_dev_link(struct net_device *dev,
struct net_device *upper_dev, bool master,
void *upper_priv, void *upper_info,
@@ -8037,6 +8082,7 @@ static int __netdev_upper_dev_link(struc
@@ -8038,6 +8083,7 @@ static int __netdev_upper_dev_link(struc
if (ret)
return ret;
@ -99,7 +99,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
ret = call_netdevice_notifiers_info(NETDEV_CHANGEUPPER,
&changeupper_info.info);
ret = notifier_to_errno(ret);
@@ -8133,6 +8179,7 @@ static void __netdev_upper_dev_unlink(st
@@ -8134,6 +8180,7 @@ static void __netdev_upper_dev_unlink(st
__netdev_adjacent_dev_unlink_neighbour(dev, upper_dev);
@ -107,7 +107,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
call_netdevice_notifiers_info(NETDEV_CHANGEUPPER,
&changeupper_info.info);
@@ -8919,6 +8966,7 @@ int dev_set_mac_address(struct net_devic
@@ -8920,6 +8967,7 @@ int dev_set_mac_address(struct net_devic
if (err)
return err;
dev->addr_assign_type = NET_ADDR_SET;