On Sat, Jan 9, 2021 at 12:35 AM Song Liu <[email protected]> wrote:
>
> To access per-task data, BPF program typically creates a hash table with
> pid as the key. This is not ideal because:
> 1. The use need to estimate requires size of the hash table, with may be
> inaccurate;
> 2. Big hash tables are slow;
> 3. To clean up the data properly during task terminations, the user need
> to write code.
>
> Task local storage overcomes these issues and becomes a better option for
> these per-task data. Task local storage is only available to BPF_LSM. Now
> enable it for tracing programs.
Also mention here that you change the pointer from being a security blob to a
dedicated member in the task struct. I assume this is because you want to
use it without CONFIG_BPF_LSM?
>
Can you also mention the reasons for changing the
raw_spin_lock_bh to raw_spin_lock_irqsave in the commit log?
> Reported-by: kernel test robot <[email protected]>
> Signed-off-by: Song Liu <[email protected]>
> ---
> include/linux/bpf.h | 7 +++++++
> include/linux/bpf_lsm.h | 22 ----------------------
> include/linux/bpf_types.h | 2 +-
> include/linux/sched.h | 5 +++++
> kernel/bpf/Makefile | 3 +--
> kernel/bpf/bpf_local_storage.c | 28 +++++++++++++++++-----------
> kernel/bpf/bpf_lsm.c | 4 ----
> kernel/bpf/bpf_task_storage.c | 26 ++++++--------------------
> kernel/fork.c | 5 +++++
> kernel/trace/bpf_trace.c | 4 ++++
> 10 files changed, 46 insertions(+), 60 deletions(-)
>
[...]
> On Jan 11, 2021, at 2:14 AM, KP Singh <[email protected]> wrote:
>
> On Sat, Jan 9, 2021 at 12:35 AM Song Liu <[email protected]> wrote:
>>
>> To access per-task data, BPF program typically creates a hash table with
>> pid as the key. This is not ideal because:
>> 1. The use need to estimate requires size of the hash table, with may be
>> inaccurate;
>> 2. Big hash tables are slow;
>> 3. To clean up the data properly during task terminations, the user need
>> to write code.
>>
>> Task local storage overcomes these issues and becomes a better option for
>> these per-task data. Task local storage is only available to BPF_LSM. Now
>> enable it for tracing programs.
>
> Also mention here that you change the pointer from being a security blob to a
> dedicated member in the task struct. I assume this is because you want to
> use it without CONFIG_BPF_LSM?
Yes, exactly. I will add this to the commit log.
>
>>
>
> Can you also mention the reasons for changing the
> raw_spin_lock_bh to raw_spin_lock_irqsave in the commit log?
This is because we will use these in irq context. I will add this to the
commit log.
Thanks,
Song