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

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Date:   Wed,  1 Jul 2020 11:47:44 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     gregkh@...uxfoundation.org, jane.pnx9@...il.com,
        daniel.m.jordan@...cle.com, simon@...anor.nu,
        harshjain32@...il.com, pakki001@....edu
Cc:     devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Souptick Joarder <jrdr.linux@...il.com>,
        John Hubbard <jhubbard@...dia.com>,
        Bharath Vedartham <linux.bhar@...il.com>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH v3 4/4] staging: kpc2000: kpc_dma: Remove additional goto statements

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@...il.com>
Cc: John Hubbard <jhubbard@...dia.com>
Cc: Bharath Vedartham <linux.bhar@...il.com>
Cc: Dan Carpenter <dan.carpenter@...cle.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