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staging: kpc2000: Convert put_page() to put_user_page*()

PATCH Superseded Bharath Vedartham 2 participants 2 messages Jul 25, 2019 – Aug 3, 2019

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Bharath Vedartham

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#0 lore raw

PATCH v4 1/1 staging: kpc2000: Convert put_page() to put_user_page*()

For pages that were retained via get_user_pages*(), release those pages via the new put_user_page*() routines, instead of via put_page().

This is part a tree-wide conversion, as described in commit fc1d8e7cca2d ("mm: introduce put_user_page*(), placeholder versions").

Cc Ira Weiny <[email protected]>
Cc John Hubbard <[email protected]>
Cc Jérôme Glisse <[email protected]>
Cc Greg Kroah-Hartman <[email protected]>
Cc Matt Sickler <[email protected]>
Cc [email protected]
Cc [email protected]
Cc [email protected]
Reviewed-by John Hubbard <[email protected]>
Signed-off-by Bharath Vedartham <[email protected]>

---
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.
Changes since v3
- Changed the changelog as suggested by John.
- Added John's Reviewed-By tag.
Changes since v4
- Rebased the patch on the staging tree.
- Improved commit log by fixing a line wrap.

---
 drivers/staging/kpc2000/kpc_dma/fileops.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)
drivers/staging/kpc2000/kpc_dma/fileops.c +6 -11
index 48ca88b..f15e292 100644
@@ -190,9 +190,7 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
 	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:

@@ -211,16 +209,13 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
 	BUG_ON(acd->ldev == NULL);
 	BUG_ON(acd->ldev->pldev == NULL);
 
-	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);
Signature · 1 line
2.7.4
#1 lore raw
Quoted 6 lines · Bharath Vedartham

For pages that were retained via get_user_pages*(), release those pages via the new put_user_page*() routines, instead of via put_page().

This is part a tree-wide conversion, as described in commit fc1d8e7cca2d ("mm: introduce put_user_page*(), placeholder versions").

Hi Bharath,

If you like, I could re-post your patch here, modified slightly, as part of the next version of the miscellaneous call site conversion series [1].

As part of that, we should change this to use put_user_pages_dirty_lock() (see below).

Quoted 50 lines
Cc Ira Weiny <[email protected]>
Cc John Hubbard <[email protected]>
Cc Jérôme Glisse <[email protected]>
Cc Greg Kroah-Hartman <[email protected]>
Cc Matt Sickler <[email protected]>
Cc [email protected]
Cc [email protected]
Cc [email protected]
Reviewed-by John Hubbard <[email protected]>
Signed-off-by Bharath Vedartham <[email protected]>

---
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.
Changes since v3
- Changed the changelog as suggested by John.
- Added John's Reviewed-By tag.
Changes since v4
- Rebased the patch on the staging tree.
- Improved commit log by fixing a line wrap.

---
 drivers/staging/kpc2000/kpc_dma/fileops.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)
drivers/staging/kpc2000/kpc_dma/fileops.c +1 -6
index 48ca88b..f15e292 100644
@@ -190,9 +190,7 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
 	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:

@@ -211,16 +209,13 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
 	BUG_ON(acd->ldev == NULL);
 	BUG_ON(acd->ldev->pldev == NULL);
 
-	for (i = 0 ; i < acd->page_count ; i++) {
-		if (!PageReserved(acd->user_pages[i])) {
-			set_page_dirty(acd->user_pages[i]);

drivers/staging/kpc2000/kpc_dma/fileops.c void transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags) · line 216

Quoted 10 lines
drivers/staging/kpc2000/kpc_dma/fileops.c +3 -5
-		}
-	}
-
 	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);

This would change to:

			put_user_pages_dirty_lock(&acd->user_pages[i], 1, true);

...and we'd add this blurb (this time with CH's name spelled properly) to the commit description:

Note that this effectively changes the code's behavior in qp_release_pages(): it now ultimately calls set_page_dirty_lock(), instead of set_page_dirty(). This is probably more accurate.

As Christoph Hellwig put it, "set_page_dirty() is only safe if we are dealing with a file backed page where we have reference on the inode it hangs off." [1]

[1] https://lore.kernel.org/r/[email protected]

Also, future: I don't know the driver well enough to say, but maybe "true" could be replaced by "acd->ldev->dir == DMA_FROM_DEVICE", there, but that would be a separate patch.

thanks,

Signature · 2 lines
John Hubbard
NVIDIA
Quoted 6 lines
drivers/staging/kpc2000/kpc_dma/fileops.c +2 -0
+		else
+			put_user_page(acd->user_pages[i]);
 	}
 
 	sg_free_table(&acd->sgt);