From: John Hubbard <jhubbard@nvidia.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Souptick Joarder <jrdr.linux@gmail.com>,
Matthew Wilcox <willy@infradead.org>,
Jani Nikula <jani.nikula@linux.intel.com>,
"Joonas Lahtinen" <joonas.lahtinen@linux.intel.com>,
Rodrigo Vivi <rodrigo.vivi@intel.com>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
Chris Wilson <chris@chris-wilson.co.uk>,
Tvrtko Ursulin <tvrtko.ursulin@intel.com>,
Matthew Auld <matthew.auld@intel.com>,
<intel-gfx@lists.freedesktop.org>,
<dri-devel@lists.freedesktop.org>,
LKML <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
John Hubbard <jhubbard@nvidia.com>
Subject: [PATCH v2 3/4] mm/gup: introduce pin_user_pages_fast_only()
Date: Thu, 21 May 2020 22:19:30 -0700 [thread overview]
Message-ID: <20200522051931.54191-4-jhubbard@nvidia.com> (raw)
In-Reply-To: <20200522051931.54191-1-jhubbard@nvidia.com>
This is the FOLL_PIN equivalent of __get_user_pages_fast(),
except with a more descriptive name, and gup_flags instead of
a boolean "write" in the argument list.
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
include/linux/mm.h | 2 ++
mm/gup.c | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 38 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 84b601cab699..98be7289d7e9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1820,6 +1820,8 @@ extern int mprotect_fixup(struct vm_area_struct *vma,
*/
int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages);
+int pin_user_pages_fast_only(unsigned long start, int nr_pages,
+ unsigned int gup_flags, struct page **pages);
/*
* per-process(per-mm_struct) statistics.
*/
diff --git a/mm/gup.c b/mm/gup.c
index 4564b0dc7d0b..6fa9b2016a53 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2859,6 +2859,42 @@ int pin_user_pages_fast(unsigned long start, int nr_pages,
}
EXPORT_SYMBOL_GPL(pin_user_pages_fast);
+/*
+ * This is the FOLL_PIN equivalent of __get_user_pages_fast(). Behavior is the
+ * same, except that this one sets FOLL_PIN instead of FOLL_GET.
+ *
+ * The API rules are the same, too: no negative values may be returned.
+ */
+int pin_user_pages_fast_only(unsigned long start, int nr_pages,
+ unsigned int gup_flags, struct page **pages)
+{
+ int nr_pinned;
+
+ /*
+ * FOLL_GET and FOLL_PIN are mutually exclusive. Note that the API
+ * rules require returning 0, rather than -errno:
+ */
+ if (WARN_ON_ONCE(gup_flags & FOLL_GET))
+ return 0;
+ /*
+ * FOLL_FAST_ONLY is required in order to match the API description of
+ * this routine: no fall back to regular ("slow") GUP.
+ */
+ gup_flags |= (FOLL_PIN | FOLL_FAST_ONLY);
+ nr_pinned = internal_get_user_pages_fast(start, nr_pages, gup_flags,
+ pages);
+ /*
+ * This routine is not allowed to return negative values. However,
+ * internal_get_user_pages_fast() *can* return -errno. Therefore,
+ * correct for that here:
+ */
+ if (nr_pinned < 0)
+ nr_pinned = 0;
+
+ return nr_pinned;
+}
+EXPORT_SYMBOL_GPL(pin_user_pages_fast_only);
+
/**
* pin_user_pages_remote() - pin pages of a remote process (task != current)
*
--
2.26.2
next prev parent reply other threads:[~2020-05-22 5:19 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-22 5:19 [PATCH v2 0/4] mm/gup, drm/i915: refactor gup_fast, convert to pin_user_pages() John Hubbard
2020-05-22 5:19 ` [PATCH v2 1/4] mm/gup: move __get_user_pages_fast() down a few lines in gup.c John Hubbard
2020-05-22 5:19 ` [PATCH v2 2/4] mm/gup: refactor and de-duplicate gup_fast() code John Hubbard
2020-05-22 5:19 ` John Hubbard [this message]
2020-05-22 5:19 ` [PATCH v2 4/4] drm/i915: convert get_user_pages() --> pin_user_pages() John Hubbard
2020-05-23 9:41 ` [PATCH v2 0/4] mm/gup, drm/i915: refactor gup_fast, convert to pin_user_pages() Chris Wilson
2020-05-23 22:33 ` John Hubbard
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200522051931.54191-4-jhubbard@nvidia.com \
--to=jhubbard@nvidia.com \
--cc=airlied@linux.ie \
--cc=akpm@linux-foundation.org \
--cc=chris@chris-wilson.co.uk \
--cc=daniel@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=intel-gfx@lists.freedesktop.org \
--cc=jani.nikula@linux.intel.com \
--cc=joonas.lahtinen@linux.intel.com \
--cc=jrdr.linux@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=matthew.auld@intel.com \
--cc=rodrigo.vivi@intel.com \
--cc=tvrtko.ursulin@intel.com \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).