[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Tue, 7 Jul 2020 13:45:42 +0200
From: Jürgen Groß <jgross@...e.com>
To: Souptick Joarder <jrdr.linux@...il.com>
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>,
sstabellini@...nel.org, xen-devel@...ts.xenproject.org,
linux-kernel@...r.kernel.org, John Hubbard <jhubbard@...dia.com>,
Paul Durrant <xadimgnik@...il.com>
Subject: Re: [PATCH v2 1/3] xen/privcmd: Corrected error handling path
On 07.07.20 13:40, Souptick Joarder wrote:
> On Tue, Jul 7, 2020 at 3:05 PM Jürgen Groß <jgross@...e.com> wrote:
>>
>> On 06.07.20 20:16, Souptick Joarder wrote:
>>> Previously, if lock_pages() end up partially mapping pages, it used
>>> to return -ERRNO due to which unlock_pages() have to go through
>>> each pages[i] till *nr_pages* to validate them. This can be avoided
>>> by passing correct number of partially mapped pages & -ERRNO separately,
>>> while returning from lock_pages() due to error.
>>>
>>> With this fix unlock_pages() doesn't need to validate pages[i] till
>>> *nr_pages* for error scenario and few condition checks can be ignored.
>>>
>>> Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
>>> Cc: John Hubbard <jhubbard@...dia.com>
>>> Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
>>> Cc: Paul Durrant <xadimgnik@...il.com>
>>> ---
>>> drivers/xen/privcmd.c | 31 +++++++++++++++----------------
>>> 1 file changed, 15 insertions(+), 16 deletions(-)
>>>
>>> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
>>> index a250d11..33677ea 100644
>>> --- a/drivers/xen/privcmd.c
>>> +++ b/drivers/xen/privcmd.c
>>> @@ -580,13 +580,13 @@ static long privcmd_ioctl_mmap_batch(
>>>
>>> static int lock_pages(
>>> struct privcmd_dm_op_buf kbufs[], unsigned int num,
>>> - struct page *pages[], unsigned int nr_pages)
>>> + struct page *pages[], unsigned int nr_pages, unsigned int *pinned)
>>> {
>>> unsigned int i;
>>> + int page_count = 0;
>>
>> Initial value shouldn't be needed, and ...
>>
>>>
>>> for (i = 0; i < num; i++) {
>>> unsigned int requested;
>>> - int pinned;
>>
>> ... you could move the declaration here.
>>
>> With that done you can add my
>>
>> Reviewed-by: Juergen Gross <jgross@...e.com>
>
> Ok. But does it going make any difference other than limiting scope ?
Dropping the initializer surely does, and in the end page_count just
replaces the former pinned variable, so why would we want to widen the
scope with this patch?
Juergen
Powered by blists - more mailing lists