netdev - Re: [PATCH bpf-next v2] bpf: Add kernel symbol for struct

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Message-ID: <85160853-cc20-40df-b090-62b4359bec37@linux.dev>
Date: Mon, 4 Nov 2024 14:13:30 -0800
From: Martin KaFai Lau <martin.lau@...ux.dev>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>,
 Xu Kuohai <xukuohai@...weicloud.com>
Cc: Martin KaFai Lau <martin.lau@...nel.org>, bpf <bpf@...r.kernel.org>,
 Network Development <netdev@...r.kernel.org>,
 Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>,
 Andrii Nakryiko <andrii@...nel.org>, Eduard Zingerman <eddyz87@...il.com>,
 Yonghong Song <yonghong.song@...ux.dev>, Kui-Feng Lee <thinker.li@...il.com>
Subject: Re: [PATCH bpf-next v2] bpf: Add kernel symbol for struct_ops
 trampoline

On 11/4/24 9:53 AM, Alexei Starovoitov wrote:

> As a separate clean up I would switch the freeing to call_rcu_tasks.
> Synchronous waiting is expensive.
> 
> Martin,
> 
> any suggestions?

There is a map->rcu now. May be add a "bool free_after_rcu_tasks_gp" to "struct 
bpf_map" and do the call_rcu_tasks() in bpf_map_put(). The 
bpf_struct_ops_map_alloc() can set the map->free_after_rcu_tasks_gp.

Take this chance to remove the "st_map->rcu" from "struct bpf_struct_ops_map" 
also. It is a left over after cleaning up the kvalue->refcnt in the
commit b671c2067a04 ("bpf: Retire the struct_ops map kvalue->refcnt.").

Xu, it will be great if you can follow up with this cleanup. Otherwise, I will 
put it under the top of my todo list. Let me know what you prefer.