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debugfs, coccinelle: check for obsolete DEFINE_SIMPLE_ATTRIBUTE() usage 

In order to protect against file removal races, debugfs files created via
debugfs_create_file() now get wrapped by a struct file_operations at their
opening.

If the original struct file_operations are known to be safe against removal
races by themselves already, the proxy creation may be bypassed by creating
the files through debugfs_create_file_unsafe().

In order to help debugfs users who use the common
  DEFINE_SIMPLE_ATTRIBUTE() + debugfs_create_file()
idiom to transition to removal safe struct file_operations, the helper
macro DEFINE_DEBUGFS_ATTRIBUTE() has been introduced.

Thus, the preferred strategy is to use
  DEFINE_DEBUGFS_ATTRIBUTE() + debugfs_create_file_unsafe()
now.

Introduce a Coccinelle script that searches for
DEFINE_SIMPLE_ATTRIBUTE()-defined struct file_operations handed into
debugfs_create_file(). Suggest to turn these usages into the
  DEFINE_DEBUGFS_ATTRIBUTE() + debugfs_create_file_unsafe()
pattern.

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Acked-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nicolai Stange 2016-03-22 14:11:16 +01:00 committed by Greg Kroah-Hartman
parent c646880814
commit 5103068eac
1 changed files with 67 additions and 0 deletions
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67
scripts/coccinelle/api/debugfs/debugfs_simple_attr.cocci Normal file
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@ -0,0 +1,67 @@
/// Use DEFINE_DEBUGFS_ATTRIBUTE rather than DEFINE_SIMPLE_ATTRIBUTE
/// for debugfs files.
///
//# Rationale: DEFINE_SIMPLE_ATTRIBUTE + debugfs_create_file()
//# imposes some significant overhead as compared to
//# DEFINE_DEBUGFS_ATTRIBUTE + debugfs_create_file_unsafe().
//
// Copyright (C): 2016 Nicolai Stange
// Options: --no-includes
//
virtual context
virtual patch
virtual org
virtual report
@dsa@
declarer name DEFINE_SIMPLE_ATTRIBUTE;
identifier dsa_fops;
expression dsa_get, dsa_set, dsa_fmt;
position p;
@@
DEFINE_SIMPLE_ATTRIBUTE@p(dsa_fops, dsa_get, dsa_set, dsa_fmt);
@dcf@
expression name, mode, parent, data;
identifier dsa.dsa_fops;
@@
debugfs_create_file(name, mode, parent, data, &dsa_fops)
@context_dsa depends on context && dcf@
declarer name DEFINE_DEBUGFS_ATTRIBUTE;
identifier dsa.dsa_fops;
expression dsa.dsa_get, dsa.dsa_set, dsa.dsa_fmt;
@@
* DEFINE_SIMPLE_ATTRIBUTE(dsa_fops, dsa_get, dsa_set, dsa_fmt);
@patch_dcf depends on patch expression@
expression name, mode, parent, data;
identifier dsa.dsa_fops;
@@
- debugfs_create_file(name, mode, parent, data, &dsa_fops)
+ debugfs_create_file_unsafe(name, mode, parent, data, &dsa_fops)
@patch_dsa depends on patch_dcf && patch@
identifier dsa.dsa_fops;
expression dsa.dsa_get, dsa.dsa_set, dsa.dsa_fmt;
@@
- DEFINE_SIMPLE_ATTRIBUTE(dsa_fops, dsa_get, dsa_set, dsa_fmt);
+ DEFINE_DEBUGFS_ATTRIBUTE(dsa_fops, dsa_get, dsa_set, dsa_fmt);
@script:python depends on org && dcf@
fops << dsa.dsa_fops;
p << dsa.p;
@@
msg="%s should be defined with DEFINE_DEBUGFS_ATTRIBUTE" % (fops)
coccilib.org.print_todo(p[0], msg)
@script:python depends on report && dcf@
fops << dsa.dsa_fops;
p << dsa.p;
@@
msg="WARNING: %s should be defined with DEFINE_DEBUGFS_ATTRIBUTE" % (fops)
coccilib.report.print_report(p[0], msg)