From: Eric Blake <eblake@redhat.com>
To: Gonglei <arei.gonglei@huawei.com>
Cc: "kwolf@redhat.com" <kwolf@redhat.com>,
"Huangweidong \(C\)" <weidong.huang@huawei.com>,
Zhanghailiang <zhang.zhanghailiang@huawei.com>,
"qemu-trivial@nongnu.org" <qemu-trivial@nongnu.org>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"stefanha@redhat.com" <stefanha@redhat.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>
Subject: Re: [Qemu-trivial] [Qemu-devel] [PATCH] oslib-posix: change free to g_free
Date: Fri, 10 Oct 2014 21:44:59 -0600 [thread overview]
Message-ID: <5438A7BB.3060109@redhat.com> (raw)
In-Reply-To: <5438A4E2.4090007@huawei.com>
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On 10/10/2014 09:32 PM, Gonglei wrote:
>>> Actually, I had noted that C standard says it is a no-operation.
>>> But that doesn't mean that every C-library handles it like that.
>>
>> EVERY libc that is C89 compliant handles it like that. The last
>> platform that failed on free(NULL) was SunOS 4, which is such
>> museum-ware it's not funny. There is no need to cater to platforms from
>> 25 years ago.
>
> But why some callers make a check,
> but some other callers don't do this check?
Because some people haven't learned that free(NULL) is safe yet. You're
welcome to simplify code as you touch it.
> Can I consider those check is superfluous?
Yes. Checking for NULL before calling free() or g_free() is wasted effort.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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WARNING: multiple messages have this Message-ID (diff)
From: Eric Blake <eblake@redhat.com>
To: Gonglei <arei.gonglei@huawei.com>
Cc: "kwolf@redhat.com" <kwolf@redhat.com>,
"Huangweidong (C)" <weidong.huang@huawei.com>,
Zhanghailiang <zhang.zhanghailiang@huawei.com>,
"qemu-trivial@nongnu.org" <qemu-trivial@nongnu.org>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"stefanha@redhat.com" <stefanha@redhat.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>
Subject: Re: [Qemu-devel] [PATCH] oslib-posix: change free to g_free
Date: Fri, 10 Oct 2014 21:44:59 -0600 [thread overview]
Message-ID: <5438A7BB.3060109@redhat.com> (raw)
In-Reply-To: <5438A4E2.4090007@huawei.com>
[-- Attachment #1: Type: text/plain, Size: 864 bytes --]
On 10/10/2014 09:32 PM, Gonglei wrote:
>>> Actually, I had noted that C standard says it is a no-operation.
>>> But that doesn't mean that every C-library handles it like that.
>>
>> EVERY libc that is C89 compliant handles it like that. The last
>> platform that failed on free(NULL) was SunOS 4, which is such
>> museum-ware it's not funny. There is no need to cater to platforms from
>> 25 years ago.
>
> But why some callers make a check,
> but some other callers don't do this check?
Because some people haven't learned that free(NULL) is safe yet. You're
welcome to simplify code as you touch it.
> Can I consider those check is superfluous?
Yes. Checking for NULL before calling free() or g_free() is wasted effort.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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next prev parent reply other threads:[~2014-10-11 3:45 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-11 2:54 [Qemu-trivial] [PATCH] oslib-posix: change free to g_free arei.gonglei
2014-10-11 2:54 ` [Qemu-devel] " arei.gonglei
2014-10-11 3:10 ` [Qemu-trivial] " zhanghailiang
2014-10-11 3:10 ` zhanghailiang
2014-10-11 3:21 ` [Qemu-trivial] " Gonglei
2014-10-11 3:21 ` Gonglei
2014-10-11 3:26 ` [Qemu-trivial] " Eric Blake
2014-10-11 3:26 ` Eric Blake
2014-10-11 3:32 ` [Qemu-trivial] " Gonglei
2014-10-11 3:32 ` Gonglei
2014-10-11 3:44 ` Eric Blake [this message]
2014-10-11 3:44 ` Eric Blake
2014-10-11 3:47 ` [Qemu-trivial] " Gonglei
2014-10-11 3:47 ` Gonglei
2014-10-11 3:23 ` [Qemu-trivial] " Eric Blake
2014-10-11 3:23 ` Eric Blake
2014-10-12 7:44 ` [Qemu-trivial] " Kevin Wolf
2014-10-12 7:44 ` Kevin Wolf
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