| Message ID | 1594059372-15563-2-git-send-email-jrdr.linux@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Few bug fixes and Convert to pin_user_pages*() | expand |
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@gmail.com> > Cc: John Hubbard <jhubbard@nvidia.com> > Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> > Cc: Paul Durrant <xadimgnik@gmail.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@suse.com> Juergen
On Tue, Jul 7, 2020 at 3:05 PM Jürgen Groß <jgross@suse.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@gmail.com> > > Cc: John Hubbard <jhubbard@nvidia.com> > > Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> > > Cc: Paul Durrant <xadimgnik@gmail.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@suse.com> Ok. But does it going make any difference other than limiting scope ? > > > Juergen
On 07.07.20 13:40, Souptick Joarder wrote: > On Tue, Jul 7, 2020 at 3:05 PM Jürgen Groß <jgross@suse.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@gmail.com> >>> Cc: John Hubbard <jhubbard@nvidia.com> >>> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> >>> Cc: Paul Durrant <xadimgnik@gmail.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@suse.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
On Tue, Jul 7, 2020 at 5:15 PM Jürgen Groß <jgross@suse.com> wrote: > > On 07.07.20 13:40, Souptick Joarder wrote: > > On Tue, Jul 7, 2020 at 3:05 PM Jürgen Groß <jgross@suse.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@gmail.com> > >>> Cc: John Hubbard <jhubbard@nvidia.com> > >>> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> > >>> Cc: Paul Durrant <xadimgnik@gmail.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@suse.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? Agree, no reason to move it up. Will change it in v3. > > > Juergen
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; for (i = 0; i < num; i++) { unsigned int requested; - int pinned; requested = DIV_ROUND_UP( offset_in_page(kbufs[i].uptr) + kbufs[i].size, @@ -594,14 +594,15 @@ 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; @@ -611,13 +612,8 @@ 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) @@ -630,6 +626,7 @@ 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; @@ -683,9 +680,11 @@ 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);
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> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Paul Durrant <xadimgnik@gmail.com> --- drivers/xen/privcmd.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-)