2023-06-30 06:07:19

by Zqiang

Subject: [PATCH v2] net: Destroy previously created kthreads after failing to set napi threaded mode

When setting 1 to enable napi threaded mode, will traverse dev->napi_list
and create kthread for napi->thread, if creation fails, the dev->threaded
will be set to false and we will clear NAPI_STATE_THREADED bit for all
napi->state in dev->napi_list, even if some napi that has successfully
created the kthread before. as a result, for successfully created napi
kthread, they will never be used.

This commit therefore destroy previously created napi->thread if setting
napi threaded mode fails.

Signed-off-by: Zqiang <[email protected]>
---
v1->v2:
Set napi->thread pointer is NULL.

net/core/dev.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 69a3e544676c..6125a1b1e019 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6317,10 +6317,15 @@ int dev_set_threaded(struct net_device *dev, bool threaded)
* This should not cause hiccups/stalls to the live traffic.
*/
list_for_each_entry(napi, &dev->napi_list, dev_list) {
- if (threaded)
+ if (threaded) {
set_bit(NAPI_STATE_THREADED, &napi->state);
- else
+ } else {
clear_bit(NAPI_STATE_THREADED, &napi->state);
+ if (napi->thread) {
+ kthread_stop(napi->thread);
+ napi->thread = NULL;
+ }
+ }
}

return err;
--
2.17.1

2023-06-30 15:37:00

by Jakub Kicinski

Subject: Re: [PATCH v2] net: Destroy previously created kthreads after failing to set napi threaded mode

On Fri, 30 Jun 2023 13:43:53 +0800 Zqiang wrote:
> When setting 1 to enable napi threaded mode, will traverse dev->napi_list
> and create kthread for napi->thread, if creation fails, the dev->threaded
> will be set to false and we will clear NAPI_STATE_THREADED bit for all
> napi->state in dev->napi_list, even if some napi that has successfully
> created the kthread before. as a result, for successfully created napi
> kthread, they will never be used.
>
> This commit therefore destroy previously created napi->thread if setting
> napi threaded mode fails.

Please don't send two patches in less than 24h, unless someone asks you
to on the list. A lot of people read the list from the oldest postings,
won't notice the newer one, and it will split the discussion.
--
pw-bot: cr