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Message-Id: <1457469802-11850-12-git-send-email-jglisse@redhat.com>
Date: Tue, 8 Mar 2016 15:43:04 -0500
From: Jérôme Glisse <jglisse@...hat.com>
To: akpm@...ux-foundation.org, <linux-kernel@...r.kernel.org>,
linux-mm@...ck.org
Cc: Linus Torvalds <torvalds@...ux-foundation.org>, <joro@...tes.org>,
Mel Gorman <mgorman@...e.de>, "H. Peter Anvin" <hpa@...or.com>,
Peter Zijlstra <peterz@...radead.org>,
Andrea Arcangeli <aarcange@...hat.com>,
Johannes Weiner <jweiner@...hat.com>,
Larry Woodman <lwoodman@...hat.com>,
Rik van Riel <riel@...hat.com>,
Dave Airlie <airlied@...hat.com>,
Brendan Conoboy <blc@...hat.com>,
Joe Donohue <jdonohue@...hat.com>,
Christophe Harle <charle@...dia.com>,
Duncan Poole <dpoole@...dia.com>,
Sherry Cheung <SCheung@...dia.com>,
Subhash Gutti <sgutti@...dia.com>,
John Hubbard <jhubbard@...dia.com>,
Mark Hairgrove <mhairgrove@...dia.com>,
Lucien Dunning <ldunning@...dia.com>,
Cameron Buschardt <cabuschardt@...dia.com>,
Arvind Gopalakrishnan <arvindg@...dia.com>,
Haggai Eran <haggaie@...lanox.com>,
Shachar Raindel <raindel@...lanox.com>,
Liran Liss <liranl@...lanox.com>,
Roland Dreier <roland@...estorage.com>,
Ben Sander <ben.sander@....com>,
Greg Stoner <Greg.Stoner@....com>,
John Bridgman <John.Bridgman@....com>,
Michael Mantor <Michael.Mantor@....com>,
Paul Blinzer <Paul.Blinzer@....com>,
Leonid Shamis <Leonid.Shamis@....com>,
Laurent Morichetti <Laurent.Morichetti@....com>,
Alexander Deucher <Alexander.Deucher@....com>,
Jérôme Glisse <jglisse@...hat.com>
Subject: [PATCH v12 11/29] HMM: add discard range helper (to clear and free resources for a range).
A common use case is for device driver to stop caring for a range of
address long before said range is munmapped by userspace program. To
avoid keeping track of such range provide an helper function that will
free HMM resources for a range of address.
NOTE THAT DEVICE DRIVER MUST MAKE SURE THE HARDWARE WILL NO LONGER
ACCESS THE RANGE BECAUSE CALLING THIS HELPER !
Signed-off-by: Jérôme Glisse <jglisse@...hat.com>
---
include/linux/hmm.h | 3 +++
mm/hmm.c | 24 ++++++++++++++++++++++++
2 files changed, 27 insertions(+)
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index d819ec9..10e1558 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -265,6 +265,9 @@ void hmm_mirror_unregister(struct hmm_mirror *mirror);
struct hmm_mirror *hmm_mirror_ref(struct hmm_mirror *mirror);
void hmm_mirror_unref(struct hmm_mirror **mirror);
int hmm_mirror_fault(struct hmm_mirror *mirror, struct hmm_event *event);
+void hmm_mirror_range_discard(struct hmm_mirror *mirror,
+ unsigned long start,
+ unsigned long end);
#endif /* CONFIG_HMM */
diff --git a/mm/hmm.c b/mm/hmm.c
index 7b6ba6a..548f0c5 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -921,6 +921,30 @@ out:
}
EXPORT_SYMBOL(hmm_mirror_fault);
+/* hmm_mirror_range_discard() - discard a range of address.
+ *
+ * @mirror: The mirror struct.
+ * @start: Start address of the range to discard (inclusive).
+ * @end: End address of the range to discard (exclusive).
+ *
+ * Call when device driver want to stop mirroring a range of address and free
+ * any HMM resources associated with that range (including dma mapping if any).
+ *
+ * THIS FUNCTION ASSUME THAT DRIVER ALREADY STOPPED USING THE RANGE OF ADDRESS
+ * AND THUS DO NOT PERFORM ANY SYNCHRONIZATION OR UPDATE WITH THE DRIVER TO
+ * INVALIDATE SAID RANGE.
+ */
+void hmm_mirror_range_discard(struct hmm_mirror *mirror,
+ unsigned long start,
+ unsigned long end)
+{
+ struct hmm_event event;
+
+ hmm_event_init(&event, mirror->hmm, start, end, HMM_MUNMAP);
+ hmm_mirror_update_pt(mirror, &event, NULL);
+}
+EXPORT_SYMBOL(hmm_mirror_range_discard);
+
/* hmm_mirror_register() - register mirror against current process for a device.
*
* @mirror: The mirror struct being registered.
--
2.4.3
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