linux-kernel - Re: [PATCH v2 1/3] xen/privcmd: Corrected error handling path

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Date:   Tue, 7 Jul 2020 11:35:18 +0200
From:   Jürgen Groß <jgross@...e.com>
To:     Souptick Joarder <jrdr.linux@...il.com>,
        boris.ostrovsky@...cle.com, sstabellini@...nel.org
Cc:     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 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>


Juergen