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Message-ID: <20240612104251.DDjnpfnq@linutronix.de>
Date: Wed, 12 Jun 2024 12:42:51 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Jesper Dangaard Brouer <hawk@...nel.org>
Cc: linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
"David S. Miller" <davem@...emloft.net>,
Daniel Bristot de Oliveira <bristot@...nel.org>,
Boqun Feng <boqun.feng@...il.com>,
Daniel Borkmann <daniel@...earbox.net>,
Eric Dumazet <edumazet@...gle.com>,
Frederic Weisbecker <frederic@...nel.org>,
Ingo Molnar <mingo@...hat.com>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Waiman Long <longman@...hat.com>, Will Deacon <will@...nel.org>,
Alexei Starovoitov <ast@...nel.org>,
Andrii Nakryiko <andrii@...nel.org>,
Eduard Zingerman <eddyz87@...il.com>, Hao Luo <haoluo@...gle.com>,
Jiri Olsa <jolsa@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>,
Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu <song@...nel.org>,
Stanislav Fomichev <sdf@...gle.com>,
Toke Høiland-Jørgensen <toke@...hat.com>,
Yonghong Song <yonghong.song@...ux.dev>, bpf@...r.kernel.org
Subject: Re: [PATCH v5 net-next 14/15] net: Reference bpf_redirect_info via
task_struct on PREEMPT_RT.
On 2024-06-11 10:39:20 [+0200], To Jesper Dangaard Brouer wrote:
> On 2024-06-11 09:55:11 [+0200], Jesper Dangaard Brouer wrote:
> > > struct bpf_net_context {
> > > struct bpf_redirect_info ri;
> > > struct list_head cpu_map_flush_list;
> > > struct list_head dev_map_flush_list;
> > > struct list_head xskmap_map_flush_list;
> > > + unsigned int flags;
> >
> > Why have yet another flags variable, when we already have two flags in
> > bpf_redirect_info ?
>
> Ah you want to fold this into ri member including the status for the
> lists? Could try. It is splitted in order to delay the initialisation of
> the lists, too. We would need to be careful to not overwrite the
> flags if `ri' is initialized after the lists. That would be the case
> with CONFIG_DEBUG_NET=y and not doing redirect (the empty list check
> initializes that).
What about this:
------>8----------
diff --git a/include/linux/filter.h b/include/linux/filter.h
index d2b4260d9d0be..c0349522de8fb 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -733,15 +733,22 @@ struct bpf_nh_params {
};
};
+/* flags for bpf_redirect_info kern_flags */
+#define BPF_RI_F_RF_NO_DIRECT BIT(0) /* no napi_direct on return_frame */
+#define BPF_RI_F_RI_INIT BIT(1)
+#define BPF_RI_F_CPU_MAP_INIT BIT(2)
+#define BPF_RI_F_DEV_MAP_INIT BIT(3)
+#define BPF_RI_F_XSK_MAP_INIT BIT(4)
+
struct bpf_redirect_info {
u64 tgt_index;
void *tgt_value;
struct bpf_map *map;
u32 flags;
- u32 kern_flags;
u32 map_id;
enum bpf_map_type map_type;
struct bpf_nh_params nh;
+ u32 kern_flags;
};
struct bpf_net_context {
@@ -757,14 +764,7 @@ static inline struct bpf_net_context *bpf_net_ctx_set(struct bpf_net_context *bp
if (tsk->bpf_net_context != NULL)
return NULL;
- memset(&bpf_net_ctx->ri, 0, sizeof(bpf_net_ctx->ri));
-
- if (IS_ENABLED(CONFIG_BPF_SYSCALL)) {
- INIT_LIST_HEAD(&bpf_net_ctx->cpu_map_flush_list);
- INIT_LIST_HEAD(&bpf_net_ctx->dev_map_flush_list);
- }
- if (IS_ENABLED(CONFIG_XDP_SOCKETS))
- INIT_LIST_HEAD(&bpf_net_ctx->xskmap_map_flush_list);
+ bpf_net_ctx->ri.kern_flags = 0;
tsk->bpf_net_context = bpf_net_ctx;
return bpf_net_ctx;
@@ -785,6 +785,11 @@ static inline struct bpf_redirect_info *bpf_net_ctx_get_ri(void)
{
struct bpf_net_context *bpf_net_ctx = bpf_net_ctx_get();
+ if (!(bpf_net_ctx->ri.kern_flags & BPF_RI_F_RI_INIT)) {
+ memset(&bpf_net_ctx->ri, 0, offsetof(struct bpf_net_context, ri.nh));
+ bpf_net_ctx->ri.kern_flags |= BPF_RI_F_RI_INIT;
+ }
+
return &bpf_net_ctx->ri;
}
@@ -792,6 +797,11 @@ static inline struct list_head *bpf_net_ctx_get_cpu_map_flush_list(void)
{
struct bpf_net_context *bpf_net_ctx = bpf_net_ctx_get();
+ if (!(bpf_net_ctx->ri.kern_flags & BPF_RI_F_CPU_MAP_INIT)) {
+ INIT_LIST_HEAD(&bpf_net_ctx->cpu_map_flush_list);
+ bpf_net_ctx->ri.kern_flags |= BPF_RI_F_CPU_MAP_INIT;
+ }
+
return &bpf_net_ctx->cpu_map_flush_list;
}
@@ -799,6 +809,11 @@ static inline struct list_head *bpf_net_ctx_get_dev_flush_list(void)
{
struct bpf_net_context *bpf_net_ctx = bpf_net_ctx_get();
+ if (!(bpf_net_ctx->ri.kern_flags & BPF_RI_F_DEV_MAP_INIT)) {
+ INIT_LIST_HEAD(&bpf_net_ctx->dev_map_flush_list);
+ bpf_net_ctx->ri.kern_flags |= BPF_RI_F_DEV_MAP_INIT;
+ }
+
return &bpf_net_ctx->dev_map_flush_list;
}
@@ -806,12 +821,14 @@ static inline struct list_head *bpf_net_ctx_get_xskmap_flush_list(void)
{
struct bpf_net_context *bpf_net_ctx = bpf_net_ctx_get();
+ if (!(bpf_net_ctx->ri.kern_flags & BPF_RI_F_XSK_MAP_INIT)) {
+ INIT_LIST_HEAD(&bpf_net_ctx->xskmap_map_flush_list);
+ bpf_net_ctx->ri.kern_flags |= BPF_RI_F_XSK_MAP_INIT;
+ }
+
return &bpf_net_ctx->xskmap_map_flush_list;
}
-/* flags for bpf_redirect_info kern_flags */
-#define BPF_RI_F_RF_NO_DIRECT BIT(0) /* no napi_direct on return_frame */
-
/* Compute the linear packet data range [data, data_end) which
* will be accessed by various program types (cls_bpf, act_bpf,
* lwt, ...). Subsystems allowing direct data access must (!)
------>8----------
Moving kern_flags to the end excludes it from the memset() and can be
re-used for the delayed initialisation.
Sebastian
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