cgroup files: add write_string cgroup control file method

[deliverable/linux.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 70d083c6fb6bffbc948949fdb2bea872973d86f6..3a99cc2df860ca6ef22020195521a754aada1643 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1363,6 +1363,39 @@ static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft,
        return retval;
 }
 
+static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft,
+                                  struct file *file,
+                                  const char __user *userbuf,
+                                  size_t nbytes, loff_t *unused_ppos)
+{
+       char local_buffer[64];
+       int retval = 0;
+       size_t max_bytes = cft->max_write_len;
+       char *buffer = local_buffer;
+
+       if (!max_bytes)
+               max_bytes = sizeof(local_buffer) - 1;
+       if (nbytes >= max_bytes)
+               return -E2BIG;
+       /* Allocate a dynamic buffer if we need one */
+       if (nbytes >= sizeof(local_buffer)) {
+               buffer = kmalloc(nbytes + 1, GFP_KERNEL);
+               if (buffer == NULL)
+                       return -ENOMEM;
+       }
+       if (nbytes && copy_from_user(buffer, userbuf, nbytes))
+               return -EFAULT;
+
+       buffer[nbytes] = 0;     /* nul-terminate */
+       strstrip(buffer);
+       retval = cft->write_string(cgrp, cft, buffer);
+       if (!retval)
+               retval = nbytes;
+       if (buffer != local_buffer)
+               kfree(buffer);
+       return retval;
+}
+
 static ssize_t cgroup_common_file_write(struct cgroup *cgrp,
                                           struct cftype *cft,
                                           struct file *file,
@@ -1440,6 +1473,8 @@ static ssize_t cgroup_file_write(struct file *file, const char __user *buf,
                return cft->write(cgrp, cft, file, buf, nbytes, ppos);
        if (cft->write_u64 || cft->write_s64)
                return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos);
+       if (cft->write_string)
+               return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos);
        if (cft->trigger) {
                int ret = cft->trigger(cgrp, (unsigned int)cft->private);
                return ret ? ret : nbytes;