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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@xxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Paul Durrant <xadimgnik@xxxxxxxxx>
  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@xxxxxxxx>




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