[PATCH v3 0/4] staging: kpc2000: kpc_dma: Few clean up and Convert to pin_user_pages()

[PATCH v3 0/4] staging: kpc2000: kpc_dma: Few clean up and Convert to pin_user_pages()

[Souptick Joarder]

This series contains few clean up, minor bug fixes and
Convert get_user_pages() to pin_user_pages().

I'm compile tested this, but unable to run-time test,
so any testing help is much appriciated.

v2:
        Address Dan's review comments to return -ERRNO for partially
        mapped pages and changed the other patches in series accordingly.
        Minor update in change logs.

v3:
	Address review comment to invoke the right goto level when allocation
	failed in patch[4/4].

Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Bharath Vedartham <linux.bhar@gmail.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>


Souptick Joarder (4):
  staging: kpc2000: kpc_dma: Unpin partial pinned pages
  staging: kpc2000: kpc_dma: Convert set_page_dirty() -->     
    set_page_dirty_lock()
  staging: kpc2000: kpc_dma: Convert get_user_pages() -->     
    pin_user_pages()
  staging: kpc2000: kpc_dma: Remove additional goto statements

 drivers/staging/kpc2000/kpc_dma/fileops.c | 39 +++++++++++++++++--------------
 1 file changed, 21 insertions(+), 18 deletions(-)

-- 
1.9.1

[PATCH v3 1/4] staging: kpc2000: kpc_dma: Unpin partial pinned pages

[Souptick Joarder]

There is a bug, when get_user_pages() failed but partially pinned
pages are not unpinned and positive numbers are returned instead of
-ERRNO. Fixed it.

Also, int is more appropriate type for rv. Changed it.

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Bharath Vedartham <linux.bhar@gmail.com>
---
 drivers/staging/kpc2000/kpc_dma/fileops.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
index 8975346..becdb41 100644
--- a/drivers/staging/kpc2000/kpc_dma/fileops.c
+++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
@@ -35,7 +35,7 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
 			    unsigned long iov_base, size_t iov_len)
 {
 	unsigned int i = 0;
-	long rv = 0;
+	int rv = 0;
 	struct kpc_dma_device *ldev;
 	struct aio_cb_data *acd;
 	DECLARE_COMPLETION_ONSTACK(done);
@@ -79,14 +79,14 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
 	rv = get_user_pages(iov_base, acd->page_count, FOLL_TOUCH | FOLL_WRITE | FOLL_GET, acd->user_pages, NULL);
 	mmap_read_unlock(current->mm);        /*  release the semaphore */
 	if (rv != acd->page_count) {
-		dev_err(&priv->ldev->pldev->dev, "Couldn't get_user_pages (%ld)\n", rv);
+		dev_err(&priv->ldev->pldev->dev, "Couldn't get_user_pages (%d)\n", rv);
 		goto err_get_user_pages;
 	}
 
 	// Allocate and setup the sg_table (scatterlist entries)
 	rv = sg_alloc_table_from_pages(&acd->sgt, acd->user_pages, acd->page_count, iov_base & (PAGE_SIZE - 1), iov_len, GFP_KERNEL);
 	if (rv) {
-		dev_err(&priv->ldev->pldev->dev, "Couldn't alloc sg_table (%ld)\n", rv);
+		dev_err(&priv->ldev->pldev->dev, "Couldn't alloc sg_table (%d)\n", rv);
 		goto err_alloc_sg_table;
 	}
 
@@ -193,10 +193,15 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
 		put_page(acd->user_pages[i]);
 
  err_get_user_pages:
+	if (rv > 0) {
+		for (i = 0; i < rv; i++)
+			put_pages(acd->user_pages[i]);
+		rv = -EFAULT;
+	}
 	kfree(acd->user_pages);
  err_alloc_userpages:
 	kfree(acd);
-	dev_dbg(&priv->ldev->pldev->dev, "%s returning with error %ld\n", __func__, rv);
+	dev_dbg(&priv->ldev->pldev->dev, "%s returning with error %d\n", __func__, rv);
 	return rv;
 }
 
-- 
1.9.1

[PATCH v3 2/4] staging: kpc2000: kpc_dma: Convert set_page_dirty() --> set_page_dirty_lock()

[Souptick Joarder]

First, convert set_page_dirty() to set_page_dirty_lock()

Second, there is an interval in there after set_page_dirty() and
before put_page(), in which the device could be running and setting
pages dirty. Moving set_page_dirty_lock() after dma_unmap_sg().

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Suggested-by: John Hubbard <jhubbard@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Bharath Vedartham <linux.bhar@gmail.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/staging/kpc2000/kpc_dma/fileops.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
index becdb41..08d90a6 100644
--- a/drivers/staging/kpc2000/kpc_dma/fileops.c
+++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
@@ -215,13 +215,13 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
 	BUG_ON(!acd->ldev);
 	BUG_ON(!acd->ldev->pldev);
 
+	dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
+
 	for (i = 0 ; i < acd->page_count ; i++) {
 		if (!PageReserved(acd->user_pages[i]))
-			set_page_dirty(acd->user_pages[i]);
+			set_page_dirty_lock(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]);
 
-- 
1.9.1

[PATCH v3 3/4] staging: kpc2000: kpc_dma: Convert get_user_pages() --> pin_user_pages()

[Souptick Joarder]

In 2019, we introduced pin_user_pages*() and now we are converting
get_user_pages*() to the new API as appropriate. [1] & [2] could
be referred for more information. This is case 2 as per document [1].

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
        https://lwn.net/Articles/807108/

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Bharath Vedartham <linux.bhar@gmail.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/staging/kpc2000/kpc_dma/fileops.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
index 08d90a6..8cd20ad 100644
--- a/drivers/staging/kpc2000/kpc_dma/fileops.c
+++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
@@ -76,10 +76,10 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
 
 	// Lock the user buffer pages in memory, and hold on to the page pointers (for the sglist)
 	mmap_read_lock(current->mm);      /*  get memory map semaphore */
-	rv = get_user_pages(iov_base, acd->page_count, FOLL_TOUCH | FOLL_WRITE | FOLL_GET, acd->user_pages, NULL);
+	rv = pin_user_pages(iov_base, acd->page_count, FOLL_TOUCH | FOLL_WRITE, acd->user_pages, NULL);
 	mmap_read_unlock(current->mm);        /*  release the semaphore */
 	if (rv != acd->page_count) {
-		dev_err(&priv->ldev->pldev->dev, "Couldn't get_user_pages (%d)\n", rv);
+		dev_err(&priv->ldev->pldev->dev, "Couldn't pin_user_pages (%d)\n", rv);
 		goto err_get_user_pages;
 	}
 
@@ -189,13 +189,11 @@ 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]);
+	unpin_user_pages(acd->user_pages, acd->page_count);
 
  err_get_user_pages:
 	if (rv > 0) {
-		for (i = 0; i < rv; i++)
-			put_pages(acd->user_pages[i]);
+		unpin_user_pages(acd->user_pages, rv);
 		rv = -EFAULT;
 	}
 	kfree(acd->user_pages);
@@ -222,8 +220,7 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
 			set_page_dirty_lock(acd->user_pages[i]);
 	}
 
-	for (i = 0 ; i < acd->page_count ; i++)
-		put_page(acd->user_pages[i]);
+	unpin_user_pages(acd->user_pages, acd->page_count);
 
 	sg_free_table(&acd->sgt);
 
-- 
1.9.1

[PATCH v3 4/4] staging: kpc2000: kpc_dma: Remove additional goto statements

[Souptick Joarder]

As 3 goto level referring to same common code, those can be
accomodated with a single goto level and renameing it to
unpin_pages. Set the -ERRNO when returning partial mapped
pages in more appropriate place.

When dma_map_sg() failed, the previously allocated memory was
not freed properly. This is corrected now.

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Bharath Vedartham <linux.bhar@gmail.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/staging/kpc2000/kpc_dma/fileops.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
index 8cd20ad..dd716edd 100644
--- a/drivers/staging/kpc2000/kpc_dma/fileops.c
+++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
@@ -35,7 +35,7 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
 			    unsigned long iov_base, size_t iov_len)
 {
 	unsigned int i = 0;
-	int rv = 0;
+	int rv = 0, nr_pages = 0;
 	struct kpc_dma_device *ldev;
 	struct aio_cb_data *acd;
 	DECLARE_COMPLETION_ONSTACK(done);
@@ -79,22 +79,27 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
 	rv = pin_user_pages(iov_base, acd->page_count, FOLL_TOUCH | FOLL_WRITE, acd->user_pages, NULL);
 	mmap_read_unlock(current->mm);        /*  release the semaphore */
 	if (rv != acd->page_count) {
+		nr_pages = rv;
+		if (rv > 0)
+			rv = -EFAULT;
+
 		dev_err(&priv->ldev->pldev->dev, "Couldn't pin_user_pages (%d)\n", rv);
-		goto err_get_user_pages;
+		goto unpin_pages;
 	}
+	nr_pages = acd->page_count;
 
 	// Allocate and setup the sg_table (scatterlist entries)
 	rv = sg_alloc_table_from_pages(&acd->sgt, acd->user_pages, acd->page_count, iov_base & (PAGE_SIZE - 1), iov_len, GFP_KERNEL);
 	if (rv) {
 		dev_err(&priv->ldev->pldev->dev, "Couldn't alloc sg_table (%d)\n", rv);
-		goto err_alloc_sg_table;
+		goto unpin_pages;
 	}
 
 	// Setup the DMA mapping for all the sg entries
 	acd->mapped_entry_count = dma_map_sg(&ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, ldev->dir);
 	if (acd->mapped_entry_count <= 0) {
 		dev_err(&priv->ldev->pldev->dev, "Couldn't dma_map_sg (%d)\n", acd->mapped_entry_count);
-		goto err_dma_map_sg;
+		goto free_table;
 	}
 
 	// Calculate how many descriptors are actually needed for this transfer.
@@ -186,16 +191,12 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
  err_descr_too_many:
 	unlock_engine(ldev);
 	dma_unmap_sg(&ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, ldev->dir);
+ free_table:
 	sg_free_table(&acd->sgt);
- err_dma_map_sg:
- err_alloc_sg_table:
-	unpin_user_pages(acd->user_pages, acd->page_count);
 
- err_get_user_pages:
-	if (rv > 0) {
-		unpin_user_pages(acd->user_pages, rv);
-		rv = -EFAULT;
-	}
+ unpin_pages:
+	if (nr_pages > 0)
+		unpin_user_pages(acd->user_pages, nr_pages);
 	kfree(acd->user_pages);
  err_alloc_userpages:
 	kfree(acd);
-- 
1.9.1