There is problem, if you will use devm_ioremap_resource instead of
devm_ioremap,
than devm_ioremap_resource will call request_mem_region().
request_mem_region() allows to tell the kernel that this driver is going
to use
this range of I/O addresses, which will prevent other drivers to make an
overlapping call to request_mem_region If other driver want to use same
address
space to access then it will not allow. Means we can not share same
address space
between two driver.
Thanks
-Arvind
On Monday 12 December 2016 02:12 PM, Boris Brezillon wrote:
On Mon, 12 Dec 2016 08:30:04 +0530
Arvind Yadav <arvind.yadav...@gmail.com> wrote:
Here, If devm_ioremap will fail. It will return NULL.
Kernel can run into a NULL-pointer dereference.
Signed-off-by: Arvind Yadav <arvind.yadav...@gmail.com>
---
drivers/mtd/devices/docg3.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/mtd/devices/docg3.c b/drivers/mtd/devices/docg3.c
index b833e6c..ffe3db0 100644
--- a/drivers/mtd/devices/docg3.c
+++ b/drivers/mtd/devices/docg3.c
@@ -2083,9 +2083,14 @@ static int __init docg3_probe(struct platform_device
*pdev)
dev_err(dev, "No I/O memory resource defined\n");
return ret;
}
- base = devm_ioremap(dev, ress->start, DOC_IOSPACE_SIZE);
ret = -ENOMEM;
+ base = devm_ioremap(dev, ress->start, DOC_IOSPACE_SIZE);
+ if (!base) {
+ dev_err(dev, "failed to map I/O memory\n");
+ return ret;
+ }
+
cascade = devm_kzalloc(dev, sizeof(*cascade) * DOC_MAX_NBFLOORS,
GFP_KERNEL);
if (!cascade)
How about going even further and doing the following?
This way you can drop the test on rres (it's done for you in
devm_ioremap_resource()), and you can directly return the error
returned by devm_ioremap_resource().
--->8---
diff --git a/drivers/mtd/devices/docg3.c b/drivers/mtd/devices/docg3.c
index b833e6cc684c..c59b91734344 100644
--- a/drivers/mtd/devices/docg3.c
+++ b/drivers/mtd/devices/docg3.c
@@ -2077,13 +2077,10 @@ static int __init docg3_probe(struct
platform_device *pdev) int ret, floor;
struct docg3_cascade *cascade;
- ret = -ENXIO;
ress = platform_get_resource(pdev, IORESOURCE_MEM, 0);
- if (!ress) {
- dev_err(dev, "No I/O memory resource defined\n");
- return ret;
- }
- base = devm_ioremap(dev, ress->start, DOC_IOSPACE_SIZE);
+ base = devm_ioremap_resource(dev, ress);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
ret = -ENOMEM;
cascade = devm_kzalloc(dev, sizeof(*cascade) * DOC_MAX_NBFLOORS,
