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Subject[PATCH][1/2] [take 2] kobject: add add_hotplug_env_var
Add a (non-inlined) add_hotplug_env_var() function to <linux/kobject.h>
and lib/kobject.c. There's a lot of boilerplate code involved in
setting environment variables in a hotplug method, so we should have a
convenience function to consolidate it (and avoid subtle bugs).


Signed-off-by: Roland Dreier <roland@topspin.com>

Index: linux-bk/include/linux/kobject.h
===================================================================
--- linux-bk.orig/include/linux/kobject.h 2004-09-28 09:51:09.000000000 -0700
+++ linux-bk/include/linux/kobject.h 2004-09-28 09:50:49.000000000 -0700
@@ -136,6 +136,32 @@


/**
+ * add_hotplug_env_var - helper for creating hotplug environment variables
+ * @envp: Pointer to table of environment variables, as passed into
+ * hotplug() method.
+ * @num_envp: Number of environment variable slots available, as
+ * passed into hotplug() method.
+ * @cur_index: Pointer to current index into @envp. It should be
+ * initialized to 0 before the first call to add_hotplug_env_var(),
+ * and will be incremented on success.
+ * @buffer: Pointer to buffer for environment variables, as passed
+ * into hotplug() method.
+ * @buffer_size: Length of @buffer, as passed into hotplug() method.
+ * @cur_len: Pointer to current length of space used in @buffer.
+ * Should be initialized to 0 before the first call to
+ * add_hotplug_env_var(), and will be incremented on success.
+ * @format: Format for creating environment variable (of the form
+ * "XXX=%x") for snprintf().
+ *
+ * Returns 0 if environment variable was added successfully or -ENOMEM
+ * if no space was available.
+ */
+extern int add_hotplug_env_var(char **envp, int num_envp, int *cur_index,
+ char *buffer, int buffer_size, int *cur_len,
+ const char *format, ...)
+ __attribute__((format (printf, 7, 8)));
+
+/**
* Use this when initializing an embedded kset with no other
* fields to initialize.
*/
Index: linux-bk/lib/kobject.c
===================================================================
--- linux-bk.orig/lib/kobject.c 2004-09-28 09:30:17.000000000 -0700
+++ linux-bk/lib/kobject.c 2004-09-28 10:45:49.000000000 -0700
@@ -232,11 +232,51 @@
if (top_kobj->kset && top_kobj->kset->hotplug_ops)
kset_hotplug(action, top_kobj->kset, kobj);
}
-#else
+
+int add_hotplug_env_var(char **envp, int num_envp, int *cur_index,
+ char *buffer, int buffer_size, int *cur_len,
+ const char *format, ...)
+{
+ va_list args;
+
+ /*
+ * We check against num_envp - 1 to make sure there is at
+ * least one slot left after we return, since the hotplug
+ * method needs to set the last slot to NULL.
+ */
+ if (*cur_index >= num_envp - 1)
+ return -ENOMEM;
+
+ envp[*cur_index] = buffer + *cur_len;
+
+ va_start(args, format);
+ *cur_len += vsnprintf(envp[*cur_index],
+ max(buffer_size - *cur_len, 0),
+ format, args) + 1;
+ va_end(args);
+
+ if (*cur_len > buffer_size)
+ return -ENOMEM;
+
+ (*cur_index)++;
+ return 0;
+}
+EXPORT_SYMBOL(add_hotplug_env_var);
+
+#else /* CONFIG_HOTPLUG */
+
void kobject_hotplug(const char *action, struct kobject *kobj)
{
return;
}
+
+int add_hotplug_env_var(char **envp, int num_envp, int *cur_index,
+ char *buffer, int buffer_size, int *cur_len,
+ const char *format, ...)
+{
+ return 0;
+}
+EXPORT_SYMBOL(add_hotplug_env_var);
#endif /* CONFIG_HOTPLUG */

/**
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