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From: Li RongQing <roy.qing.li@gmail.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk,
	fabf@skynet.be, jkosina@suse.cz,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	richard@nod.at, oleg@redhat.com, akpm@linux-foundation.org
Subject: Re: [RFC][PATCH] signal: replace !likely with unlikely!
Date: Sat, 13 Sep 2014 10:48:14 +0800	[thread overview]
Message-ID: <CAJFZqHwsjuw5As6duphrgbzxtwmE2ZqbraNEme88M3hi1WBiRQ@mail.gmail.com> (raw)
In-Reply-To: <20140911191830.GA31511@roeck-us.net>

I did not test, how to test it?

On Fri, Sep 12, 2014 at 3:18 AM, Guenter Roeck <linux@roeck-us.net> wrote:
> On Thu, Sep 11, 2014 at 08:48:16AM +0800, roy.qing.li@gmail.com wrote:
>> From: Li RongQing <roy.qing.li@gmail.com>
>>
>> !likely() is hard to be understood, and I do not know if compiler can
>> optimise this condition, but unlikely(!()) is clear
>>
>> Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
>> ---
>>  kernel/signal.c |    2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/kernel/signal.c b/kernel/signal.c
>> index 8f0876f..6156cfa 100644
>> --- a/kernel/signal.c
>> +++ b/kernel/signal.c
>> @@ -1571,7 +1571,7 @@ int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
>>       BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
>>
>>       ret = -1;
>> -     if (!likely(lock_task_sighand(t, &flags)))
>> +     if (unlikely(!lock_task_sighand(t, &flags)))
>
> I wonder if you tested this code. Seems to be unlikely (punt not intended).
>
> Guenter
>
>>               goto ret;
>>
>>       ret = 1; /* the signal is ignored */
>> --
>> 1.7.10.4
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at  http://www.tux.org/lkml/
>>
>>

  reply	other threads:[~2014-09-13  2:48 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-11  0:48 [RFC][PATCH] signal: replace !likely with unlikely! roy.qing.li
2014-09-11 19:18 ` Guenter Roeck
2014-09-13  2:48   ` Li RongQing [this message]
2014-09-13 10:04     ` Richard Weinberger
2014-09-13 13:28       ` Guenter Roeck

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