From: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Date: Sun, 16 May 2010 23:18:32 +0000 (-0300)
Subject: The proc filesystem.
X-Git-Url: http://git.cascardo.info/?p=cascardo%2Fkernel%2Fslides%2F.git;a=commitdiff_plain;h=c7ac8a066afc7bad2b462081eaf0255270e73b09

The proc filesystem.

Still needs to talk about seq_file.
---

diff --git a/05debug/debug b/05debug/debug
index 0bd8f03..17552ee 100644
--- a/05debug/debug
+++ b/05debug/debug
@@ -89,3 +89,32 @@ allowing the user to configure it.
 * Depends on DEBUG\\_FS
 * Documented in the Kconfig help at lib/Kconfig.debug
 * Also documented at Documentation/dynamic-debug-howto.txt
+
+# Proc filesystem
+
+The proc filesystem has a use of its own, allowing user space to get
+information about processes and other system configuration as well as to
+change those configuration items.
+
+However, it may be used for debugging too. In fact, developers usually
+request information from /proc/, when trying to find a solution for a
+reported bug.
+
+# Creating a proc file
+
+* include linux/proc\\_fs.h
+* struct proc\\_dir\\_entry
+	- proc\\_fops
+	- data
+* create\\_proc\\_entry(name, mode, parent) is racy
+* Use NULL parent to create a file in the proc root
+* proc\\_create(name, mode, parent, fops) is not racy
+* proc\\_create\\_data(name, mode, parent, fops, data)
+
+# Removing a proc file and creating directories
+
+* remove\\_proc\\_entry(name, parent)
+* proc\\_mkdir(name, parent)
+* proc\\_mkdir\\_mode(name, mode, parent)
+
+# seq\\_file