From: Bharath Vedartham <linux.bhar@gmail.com>
To: jhubbard@nvidia.com, ira.weiny@intel.com, jglisse@redhat.com,
gregkh@linuxfoundation.org, Matt.Sickler@daktronics.com
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
devel@driverdev.osuosl.org
Subject: [PATCH v3] staging: kpc2000: Convert put_page to put_user_page*()
Date: Sat, 20 Jul 2019 01:32:35 +0530 [thread overview]
Message-ID: <20190719200235.GA16122@bharath12345-Inspiron-5559> (raw)
There have been issues with coordination of various subsystems using
get_user_pages. These issues are better described in [1].
An implementation of tracking get_user_pages is currently underway
The implementation requires the use put_user_page*() variants to release
a reference rather than put_page(). The commit that introduced
put_user_pages, Commit fc1d8e7cca2daa18d2fe56b94874848adf89d7f5 ("mm: introduce
put_user_page*(), placeholder version").
The implementation currently simply calls put_page() within
put_user_page(). But in the future, it is to change to add a mechanism
to keep track of get_user_pages. Once a tracking mechanism is
implemented, we can make attempts to work on improving on coordination
between various subsystems using get_user_pages.
[1] https://lwn.net/Articles/753027/
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Matt Sickler <Matt.Sickler@daktronics.com>
Cc: devel@driverdev.osuosl.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: Bharath Vedartham <linux.bhar@gmail.com>
---
Changes since v1
- Improved changelog by John's suggestion.
- Moved logic to dirty pages below sg_dma_unmap
and removed PageReserved check.
Changes since v2
- Added back PageResevered check as suggested by John Hubbard.
The PageReserved check needs a closer look and is not worth messing
around with for now.
Matt, Could you give any suggestions for testing this patch?
If in-case, you are willing to pick this up to test. Could you
apply this patch to this tree
https://github.com/johnhubbard/linux/tree/gup_dma_core
and test it with your devices?
---
drivers/staging/kpc2000/kpc_dma/fileops.c | 17 ++++++-----------
1 file changed, 6 insertions(+), 11 deletions(-)
diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
index 6166587..75ad263 100644
--- a/drivers/staging/kpc2000/kpc_dma/fileops.c
+++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
@@ -198,9 +198,7 @@ int kpc_dma_transfer(struct dev_private_data *priv, struct kiocb *kcb, unsigned
sg_free_table(&acd->sgt);
err_dma_map_sg:
err_alloc_sg_table:
- for (i = 0 ; i < acd->page_count ; i++){
- put_page(acd->user_pages[i]);
- }
+ put_user_pages(acd->user_pages, acd->page_count);
err_get_user_pages:
kfree(acd->user_pages);
err_alloc_userpages:
@@ -221,16 +219,13 @@ void transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
dev_dbg(&acd->ldev->pldev->dev, "transfer_complete_cb(acd = [%p])\n", acd);
- for (i = 0 ; i < acd->page_count ; i++){
- if (!PageReserved(acd->user_pages[i])){
- set_page_dirty(acd->user_pages[i]);
- }
- }
-
dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
- for (i = 0 ; i < acd->page_count ; i++){
- put_page(acd->user_pages[i]);
+ for (i = 0; i < acd->page_count; i++) {
+ if (!PageReserved(acd->user_pages[i]))
+ put_user_pages_dirty(&acd->user_pages[i], 1);
+ else
+ put_user_page(acd->user_pages[i]);
}
sg_free_table(&acd->sgt);
--
2.7.4
next reply other threads:[~2019-07-19 20:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-19 20:02 Bharath Vedartham [this message]
2019-07-19 20:59 ` [PATCH v3] staging: kpc2000: Convert put_page to put_user_page*() Matt Sickler
2019-07-19 21:05 ` John Hubbard
2019-07-20 17:36 ` Bharath Vedartham
2019-07-19 21:28 ` John Hubbard
2019-07-20 17:23 ` Bharath Vedartham
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