diff mbox series

[net-next,v2,3/3] net: rps: locklessly access rflow->cpu

Message ID 20240417062721.45652-4-kerneljasonxing@gmail.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series locklessly protect left members in struct rps_dev_flow | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 933 this patch: 933
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 4 of 4 maintainers
netdev/build_clang success Errors and warnings before: 938 this patch: 938
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 944 this patch: 944
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 16 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 79 this patch: 79
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-04-18--00-00 (tests: 961)

Commit Message

Jason Xing April 17, 2024, 6:27 a.m. UTC 
From: Jason Xing <kernelxing@tencent.com>

This is the last member in struct rps_dev_flow which should be
protected locklessly. So finish it.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 net/core/dev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Jason Xing April 17, 2024, 12:24 p.m. UTC | #1 
On Wed, Apr 17, 2024 at 2:27 PM Jason Xing <kerneljasonxing@gmail.com> wrote:
>
> From: Jason Xing <kernelxing@tencent.com>
>
> This is the last member in struct rps_dev_flow which should be
> protected locklessly. So finish it.
>
> Signed-off-by: Jason Xing <kernelxing@tencent.com>
> ---
>  net/core/dev.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 40a535158e45..aeb45025e2bc 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -4533,7 +4533,7 @@ set_rps_cpu(struct net_device *dev, struct sk_buff *skb,
>                 rps_input_queue_tail_save(&rflow->last_qtail, head);
>         }
>
> -       rflow->cpu = next_cpu;
> +       WRITE_ONCE(rflow->cpu, next_cpu);
>         return rflow;
>  }
>
> @@ -4597,7 +4597,7 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
>                  * we can look at the local (per receive queue) flow table
>                  */
>                 rflow = &flow_table->flows[hash & flow_table->mask];
> -               tcpu = rflow->cpu;
> +               tcpu = READ_ONCE(rflow->cpu);

Hello Eric,

I think I don't need this one either, right? Only protecting the
writer side in set_rps_cpu() and the reader side in
rps_may_expire_flow() is enough.

Thanks,
Jason

>
>                 /*
>                  * If the desired CPU (where last recvmsg was done) is
> --
> 2.37.3
>
diff mbox series

Patch

diff --git a/net/core/dev.c b/net/core/dev.c
index 40a535158e45..aeb45025e2bc 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4533,7 +4533,7 @@  set_rps_cpu(struct net_device *dev, struct sk_buff *skb,
 		rps_input_queue_tail_save(&rflow->last_qtail, head);
 	}
 
-	rflow->cpu = next_cpu;
+	WRITE_ONCE(rflow->cpu, next_cpu);
 	return rflow;
 }
 
@@ -4597,7 +4597,7 @@  static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
 		 * we can look at the local (per receive queue) flow table
 		 */
 		rflow = &flow_table->flows[hash & flow_table->mask];
-		tcpu = rflow->cpu;
+		tcpu = READ_ONCE(rflow->cpu);
 
 		/*
 		 * If the desired CPU (where last recvmsg was done) is