From: Matthew Wilcox <willy@infradead.org>
To: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: David Laight <David.Laight@aculab.com>,
Dave Young <dyoung@redhat.com>, Baoquan He <bhe@redhat.com>,
Vivek Goyal <vgoyal@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-ia64@vger.kernel.org" <linux-ia64@vger.kernel.org>,
"linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"linux-riscv@lists.infradead.org"
<linux-riscv@lists.infradead.org>,
"linux-sh@vger.kernel.org" <linux-sh@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"kexec@lists.infradead.org" <kexec@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Xuefeng Li <lixuefeng@loongson.cn>,
Christophe Leroy <christophe.leroy@csgroup.eu>
Subject: Re: [PATCH v2 0/2] kdump: simplify code
Date: Tue, 14 Dec 2021 13:14:48 +0000 [thread overview]
Message-ID: <YbiYyDRW9aB9jFMD@casper.infradead.org> (raw)
In-Reply-To: <36440c0f-8b8a-c401-684f-6f54ce9c061e@loongson.cn>
On Tue, Dec 14, 2021 at 06:03:11PM +0800, Tiezhu Yang wrote:
> On 12/13/2021 10:43 PM, Matthew Wilcox wrote:
> > On Mon, Dec 13, 2021 at 08:30:33AM +0000, David Laight wrote:
> > > From: Matthew Wilcox
> > > > Sent: 12 December 2021 11:48
> > > >
> > > > On Sat, Dec 11, 2021 at 05:53:46PM +0000, David Laight wrote:
> > > > > From: Tiezhu Yang
> > > > > > Sent: 11 December 2021 03:33
> > > > > >
> > > > > > v2:
> > > > > > -- add copy_to_user_or_kernel() in lib/usercopy.c
> > > > > > -- define userbuf as bool type
> > > > >
> > > > > Instead of having a flag to indicate whether the buffer is user or kernel,
> > > > > would it be better to have two separate buffer pointers.
> > > > > One for a user space buffer, the other for a kernel space buffer.
> > > > > Exactly one of the buffers should always be NULL.
> > > >
> > > > No. You should be using an iov_iter instead. See
> > > > https://lore.kernel.org/all/Ya4bdB0UBJCZhUSo@casper.infradead.org/
> > > > for a start on this.
> > >
> > > iov_iter gets horribly expensive...
> >
> > Oh, right. Reading the kcore is a high-performance path, my mistake.
> >
>
> Hi,
>
> Thank you for your discussions.
>
> The intention of this patchset is to simplify the related code with no
> functional changes and no side effects.
>
> At this moment, if you are OK, I will send v3 used with inline function
> copy_to_user_or_kernel() to keep it simple, maybe other more changes can
> be done in the future if no any side effect.
That would be pointless. I already sent a series to remove this,
which you were cc'd on.
prev parent reply other threads:[~2021-12-14 13:15 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-11 3:33 [PATCH v2 0/2] kdump: simplify code Tiezhu Yang
2021-12-11 3:33 ` [PATCH v2 1/2] kdump: vmcore: remove copy_to() and add copy_to_user_or_kernel() Tiezhu Yang
2021-12-11 10:32 ` Christophe Leroy
2021-12-11 3:33 ` [PATCH v2 2/2] kdump: crashdump: use copy_to_user_or_kernel() to simplify code Tiezhu Yang
2021-12-11 17:53 ` [PATCH v2 0/2] kdump: " David Laight
2021-12-11 19:32 ` Christophe Leroy
2021-12-12 11:47 ` Matthew Wilcox
2021-12-13 8:30 ` David Laight
2021-12-13 14:43 ` Matthew Wilcox
2021-12-14 10:03 ` Tiezhu Yang
2021-12-14 13:14 ` Matthew Wilcox [this message]
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