linux-kernel - Re: How to check whether executing in atomic context?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f22d86810910141224i5f5d7725l9aa2b2262dc30ba4@mail.gmail.com>
Date:	Thu, 15 Oct 2009 00:54:03 +0530
From:	"Leonidas ." <leonidas137@...il.com>
To:	Stefan Richter <stefanr@...6.in-berlin.de>
Cc:	Gleb Natapov <gleb@...hat.com>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: How to check whether executing in atomic context?

On Thu, Oct 15, 2009 at 12:45 AM, Stefan Richter
<stefanr@...6.in-berlin.de> wrote:
> Leonidas . wrote:
>> On Wed, Oct 14, 2009 at 11:09 PM, Stefan Richter
>> <stefanr@...6.in-berlin.de> wrote:
>>> let the caller of your routine tell it whether it's atomic context
>>> or not.
> [...]
>> What makes it more complicated is this, the user might achieve the
>> functionality via instrumenting his source code, i.e. something like
>> using -finstrument flag of gcc. As per above inferences about
>> in_atomic(), in case of instrumentation there is no choice other than
>> providing all apis as atomic apis, this might not be the right thing
>> to do under all circumstances. Especially, for my code since I do lot
>> of allocations for book keeping.
>>
>> I am not aware of any Linux kernel module which can comply to this
>> kind of use case, what would be the most optimal thing to do here?
>
> And preallocation is not feasible either?
> --
> Stefan Richter
> -=====-==--= =-=- -===-
> http://arcgraph.de/sr/
>

Yes, I preallocate a buffer at module init time. But assume that, I am
profiling kmalloc(),
and number of kmallocs() done over time increases rapidly, I need to allocate
on demand as well depending on the load. (Actually, I am not profiling kmalloc,
it just makes a good example in this case). Currently, I preallocate a
large buffer
and as I reach the threshold, I try to grab small buffers as needed.
Obvious solution
here would be to grab a larger buffer, the only issue here would be it
might be just wasteful.

So, knowing the running context and allocating sounded like a better idea to me.

-Leo.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/