netdev - Re: [PATCH v4 bpf-next 1/6] bpf: enable task local storage for tracing programs

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Date:   Tue, 23 Feb 2021 20:51:26 +0000
From:   Song Liu <songliubraving@...com>
To:     Martin Lau <kafai@...com>
CC:     bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "ast@...nel.org" <ast@...nel.org>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        Kernel Team <Kernel-team@...com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        KP Singh <kpsingh@...nel.org>
Subject: Re: [PATCH v4 bpf-next 1/6] bpf: enable task local storage for
 tracing programs



> On Feb 23, 2021, at 11:23 AM, Martin Lau <kafai@...com> wrote:
> 
> On Mon, Feb 22, 2021 at 05:20:09PM -0800, Song Liu wrote:
> [ ... ]
> 
>> diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c
>> index e0da0258b732d..2034019966d44 100644
>> --- a/kernel/bpf/bpf_task_storage.c
>> +++ b/kernel/bpf/bpf_task_storage.c
>> @@ -15,7 +15,6 @@
>> #include <linux/bpf_local_storage.h>
>> #include <linux/filter.h>
>> #include <uapi/linux/btf.h>
>> -#include <linux/bpf_lsm.h>
>> #include <linux/btf_ids.h>
>> #include <linux/fdtable.h>
>> 
>> @@ -24,12 +23,8 @@ DEFINE_BPF_STORAGE_CACHE(task_cache);
>> static struct bpf_local_storage __rcu **task_storage_ptr(void *owner)
>> {
>> 	struct task_struct *task = owner;
>> -	struct bpf_storage_blob *bsb;
>> 
>> -	bsb = bpf_task(task);
>> -	if (!bsb)
>> -		return NULL;
> task_storage_ptr() no longer returns NULL.  All "!task_storage_ptr(task)"
> checks should be removed also.  e.g. In bpf_task_storage_get
> and bpf_pid_task_storage_update_elem.

Good catch! Fixed it in v5. 

Thanks,
Song

> 
>> -	return &bsb->storage;
>> +	return &task->bpf_storage;
>> }
>>