ftdev: let bufffer-specific code handle writes from userspace

This allows us to splice in information into logs from events
that were recorded in userspace.

1 files changed, 16 insertions, 0 deletions

diff --git a/litmus/ftdev.c b/litmus/ftdev.c
index 216dc0b4cb94..06fcf4cf77dc 100644
--- a/litmus/ftdev.c
+++ b/litmus/ftdev.c
@@ -114,6 +114,7 @@ static int ftdev_open(struct inode *in, struct file *filp)
                 goto out;
 
         ftdm = ftdev->minor + buf_idx;
+        ftdm->ftdev = ftdev;
         filp->private_data = ftdm;
 
         if (mutex_lock_interruptible(&ftdm->lock)) {
@@ -284,11 +285,25 @@ out:
         return err;
 }
 
+static ssize_t ftdev_write(struct file *filp, const char __user *from,
+                           size_t len, loff_t *f_pos)
+{
+        struct ftdev_minor* ftdm = filp->private_data;
+        ssize_t err = -EINVAL;
+        struct ftdev* ftdev = ftdm->ftdev;
+
+        /* dispatch write to buffer-specific code, if available */
+        if (ftdev->write)
+                err = ftdev->write(ftdm->buf, len, from);
+
+        return err;
+}
 
 struct file_operations ftdev_fops = {
         .owner   = THIS_MODULE,
         .open    = ftdev_open,
         .release = ftdev_release,
+        .write   = ftdev_write,
         .read    = ftdev_read,
         .unlocked_ioctl = ftdev_ioctl,
 };
@@ -308,6 +323,7 @@ int ftdev_init(	struct ftdev* ftdev, struct module* owner,
         ftdev->alloc    = NULL;
         ftdev->free     = NULL;
         ftdev->can_open = NULL;
+        ftdev->write    = NULL;
 
         ftdev->minor = kcalloc(ftdev->minor_cnt, sizeof(*ftdev->minor),
                         GFP_KERNEL);