Re: [RFC PATCH 11/13] mm/vas: Introduce VAS segments - shareable address space regions

Hi Matthew,

On Mon, 13 Mar 2017, Matthew Wilcox wrote:

On Mon, Mar 13, 2017 at 03:14:13PM -0700, Till Smejkal wrote:

quoted

+/**
+ * Create a new VAS segment.
+ *
+ * @param[in] name:		The name of the new VAS segment.
+ * @param[in] start:		The address where the VAS segment begins.
+ * @param[in] end:		The address where the VAS segment ends.
+ * @param[in] mode:		The access rights for the VAS segment.
+ *
+ * @returns:			The VAS segment ID on success, -ERRNO otherwise.
+ **/

Please follow the kernel-doc conventions, as described in
Documentation/doc-guide/kernel-doc.rst.  Also, function documentation
goes with the implementation, not the declaration.

Thank you for this pointer. I wasn't aware of this convention. I will change the
patches accordingly.

quoted

+/**
+ * Get ID of the VAS segment belonging to a given name.
+ *
+ * @param[in] name:		The name of the VAS segment for which the ID
+ *				should be returned.
+ *
+ * @returns:			The VAS segment ID on success, -ERRNO
+ *				otherwise.
+ **/
+extern int vas_seg_find(const char *name);

So ... segments have names, and IDs ... and access permissions ...
Why isn't this a special purpose filesystem?

We also thought about this. However, we decided against implementing them as a
special purpose filesystem, mainly because we could not think of a good way to
represent a VAS/VAS segment in this file system (should they be represented rather as
file or directory) and we weren't sure what a hierarchy in the filesystem would mean
for the underlying address spaces. Hence we decided against it and rather used a
combination of IDR and sysfs. However, I don't have any strong feelings and would
also reimplement them as a special purpose filesystem if people rather like them to
be one.

Till

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