| Message ID | 1594525195-28345-2-git-send-email-jrdr.linux@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | e398fb4bdf522abdeb8ddb61235bbf66065fc105 |
| Headers | show |
| Series | Few bug fixes and Convert to pin_user_pages*() | expand |
> -----Original Message----- > From: Souptick Joarder <jrdr.linux@gmail.com> > Sent: 12 July 2020 04:40 > To: boris.ostrovsky@oracle.com; jgross@suse.com; sstabellini@kernel.org > Cc: xen-devel@lists.xenproject.org; linux-kernel@vger.kernel.org; Souptick Joarder > <jrdr.linux@gmail.com>; John Hubbard <jhubbard@nvidia.com>; Paul Durrant <xadimgnik@gmail.com> > Subject: [PATCH v3 1/3] xen/privcmd: Corrected error handling path > > 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@gmail.com> > Reviewed-by: Juergen Gross <jgross@suse.com> > Cc: John Hubbard <jhubbard@nvidia.com> > Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> > Cc: Paul Durrant <xadimgnik@gmail.com> Reviewed-by: Paul Durrant <paul@xen.org> > --- > 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 5dfc59f..b001673 100644 > --- a/drivers/xen/privcmd.c > +++ b/drivers/xen/privcmd.c > @@ -579,13 +579,13 @@ 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; > > for (i = 0; i < num; i++) { > unsigned int requested; > - int pinned; > + int page_count; > > requested = DIV_ROUND_UP( > offset_in_page(kbufs[i].uptr) + kbufs[i].size, > @@ -593,14 +593,15 @@ static int lock_pages( > if (requested > nr_pages) > return -ENOSPC; > > - pinned = get_user_pages_fast( > + page_count = get_user_pages_fast( > (unsigned long) kbufs[i].uptr, > requested, FOLL_WRITE, pages); > - if (pinned < 0) > - return pinned; > + if (page_count < 0) > + return page_count; > > - nr_pages -= pinned; > - pages += pinned; > + *pinned += page_count; > + nr_pages -= page_count; > + pages += page_count; > } > > return 0; > @@ -610,13 +611,8 @@ static void unlock_pages(struct page *pages[], unsigned int nr_pages) > { > unsigned int i; > > - if (!pages) > - return; > - > - for (i = 0; i < nr_pages; i++) { > - if (pages[i]) > - put_page(pages[i]); > - } > + for (i = 0; i < nr_pages; i++) > + put_page(pages[i]); > } > > static long privcmd_ioctl_dm_op(struct file *file, void __user *udata) > @@ -629,6 +625,7 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata) > struct xen_dm_op_buf *xbufs = NULL; > unsigned int i; > long rc; > + unsigned int pinned = 0; > > if (copy_from_user(&kdata, udata, sizeof(kdata))) > return -EFAULT; > @@ -682,9 +679,11 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata) > goto out; > } > > - rc = lock_pages(kbufs, kdata.num, pages, nr_pages); > - if (rc) > + rc = lock_pages(kbufs, kdata.num, pages, nr_pages, &pinned); > + if (rc < 0) { > + nr_pages = pinned; > goto out; > + } > > for (i = 0; i < kdata.num; i++) { > set_xen_guest_handle(xbufs[i].h, kbufs[i].uptr); > -- > 1.9.1
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index 5dfc59f..b001673 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -579,13 +579,13 @@ 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; for (i = 0; i < num; i++) { unsigned int requested; - int pinned; + int page_count; requested = DIV_ROUND_UP( offset_in_page(kbufs[i].uptr) + kbufs[i].size, @@ -593,14 +593,15 @@ static int lock_pages( if (requested > nr_pages) return -ENOSPC; - pinned = get_user_pages_fast( + page_count = get_user_pages_fast( (unsigned long) kbufs[i].uptr, requested, FOLL_WRITE, pages); - if (pinned < 0) - return pinned; + if (page_count < 0) + return page_count; - nr_pages -= pinned; - pages += pinned; + *pinned += page_count; + nr_pages -= page_count; + pages += page_count; } return 0; @@ -610,13 +611,8 @@ static void unlock_pages(struct page *pages[], unsigned int nr_pages) { unsigned int i; - if (!pages) - return; - - for (i = 0; i < nr_pages; i++) { - if (pages[i]) - put_page(pages[i]); - } + for (i = 0; i < nr_pages; i++) + put_page(pages[i]); } static long privcmd_ioctl_dm_op(struct file *file, void __user *udata) @@ -629,6 +625,7 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata) struct xen_dm_op_buf *xbufs = NULL; unsigned int i; long rc; + unsigned int pinned = 0; if (copy_from_user(&kdata, udata, sizeof(kdata))) return -EFAULT; @@ -682,9 +679,11 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata) goto out; } - rc = lock_pages(kbufs, kdata.num, pages, nr_pages); - if (rc) + rc = lock_pages(kbufs, kdata.num, pages, nr_pages, &pinned); + if (rc < 0) { + nr_pages = pinned; goto out; + } for (i = 0; i < kdata.num; i++) { set_xen_guest_handle(xbufs[i].h, kbufs[i].uptr);