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Subject[RFC PATCH v4 2/3] vfio: platform: access device property as a list of strings
Date
From: Antonios Motakis <a.motakis@virtualopensystems.com>

Certain device properties (e.g. the device node name, the compatible
string), are available as a list of strings (separated by the null
terminating character). Let the VFIO user query this type of properties.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
Signed-off-by: Baptiste Reynal <b.reynal@virtualopensystems.com>

---
v3 -> v4:
- The list length is computed before strings copy. If the entire list
doesn't fit, no strings are copied to the user.
---
drivers/vfio/platform/properties.c | 43 +++++++++++++++++++++++++++++++++++++-
1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/platform/properties.c b/drivers/vfio/platform/properties.c
index 98754c2..8bf9c8f 100644
--- a/drivers/vfio/platform/properties.c
+++ b/drivers/vfio/platform/properties.c
@@ -22,7 +22,48 @@ static int dev_property_get_strings(struct device *dev, uint32_t *flags,
char *name, unsigned *lenp,
void __user *datap, unsigned long datasz)
{
- return -EINVAL;
+ const char **val;
+ int n, i, ret;
+
+ if (lenp == NULL)
+ return -EFAULT;
+
+ *lenp = 0;
+
+ n = device_property_read_string_array(dev, name, NULL, 0);
+ if (n < 0)
+ return n;
+
+ val = kcalloc(n, sizeof(char *), GFP_KERNEL);
+ if (!val)
+ return -ENOMEM;
+
+ ret = device_property_read_string_array(dev, name, val, n);
+ if (ret < 0)
+ goto out;
+
+ for (i = 0; i < n; i++)
+ *lenp += strlen(val[i]) + 1;
+
+ if (datasz < *lenp) {
+ ret = -E2BIG;
+ goto out;
+ }
+
+ for (i = 0; i < n; i++) {
+ size_t len = strlen(val[i]) + 1;
+
+ if (copy_to_user(datap, val[i], strlen(val[i]) + 1)) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ datap += len;
+ }
+
+out:
+ kfree(val);
+ return ret;
}

static int dev_property_get_uint(struct device *dev, uint32_t *flags,
--
2.5.1


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