linux-toradex.git/Documentation/fault-injection/fault-injection.txt, branch v4.4.117

futex: Fault/error injection capabilities

2015-07-20T09:45:45+00:00

Although futexes are well known for being a royal pita,
we really have very little debugging capabilities - except
for relying on tglx's eye half the time.

By simply making use of the existing fault-injection machinery,
we can improve this situation, allowing generating artificial
uaddress faults and deadlock scenarios. Of course, when this is
disabled in production systems, the overhead for failure checks
is practically zero -- so this is very cheap at the same time.
Future work would be nice to now enhance trinity to make use of
this.

There is a special tunable 'ignore-private', which can filter
out private futexes. Given the tsk->make_it_fail filter and
this option, pi futexes can be narrowed down pretty closely.

Signed-off-by: Davidlohr Bueso 
Cc: Peter Zijlstra 
Cc: Darren Hart 
Cc: Davidlohr Bueso 
Link: http://lkml.kernel.org/r/1435645562-975-3-git-send-email-dave@stgolabs.net
Signed-off-by: Thomas Gleixner

fault-injection: add tool to run command with failslab or fail_page_alloc

2012-07-31T00:25:22+00:00

This adds tools/testing/fault-injection/failcmd.sh to run a command while
injecting slab/page allocation failures via fault injection.

Example:

Run a command "make -C tools/testing/selftests/ run_tests" with
injecting slab allocation failure.

	# ./tools/testing/fault-injection/failcmd.sh \
		-- make -C tools/testing/selftests/ run_tests

Same as above except to specify 100 times failures at most instead of
one time at most by default.

	# ./tools/testing/fault-injection/failcmd.sh --times=100 \
		-- make -C tools/testing/selftests/ run_tests

Same as above except to inject page allocation failure instead of slab
allocation failure.

	# env FAILCMD_TYPE=fail_page_alloc \
		./tools/testing/fault-injection/failcmd.sh --times=100 \
		-- make -C tools/testing/selftests/ run_tests

Signed-off-by: Akinobu Mita 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fault-injection: update documentation with the mmc module param

2011-10-26T20:32:13+00:00

Signed-off-by: Per Forlin 
Reviewed-by: Akinobu Mita 
Signed-off-by: Chris Ball

fault-inject: add documentation on MMC IO fault injection

2011-10-26T19:43:34+00:00

Add description on how to enable random fault injection
for MMC IO.

Signed-off-by: Per Forlin 
Acked-by: Akinobu Mita 
Reviewed-by: Linus Walleij 
Signed-off-by: Chris Ball

fault-injection: add ability to export fault_attr in arbitrary directory

2011-08-04T00:25:20+00:00

init_fault_attr_dentries() is used to export fault_attr via debugfs.
But it can only export it in debugfs root directory.

Per Forlin is working on mmc_fail_request which adds support to inject
data errors after a completed host transfer in MMC subsystem.

The fault_attr for mmc_fail_request should be defined per mmc host and
export it in debugfs directory per mmc host like
/sys/kernel/debug/mmc0/mmc_fail_request.

init_fault_attr_dentries() doesn't help for mmc_fail_request.  So this
introduces fault_create_debugfs_attr() which is able to create a
directory in the arbitrary directory and replace
init_fault_attr_dentries().

[akpm@linux-foundation.org: extraneous semicolon, per Randy]
Signed-off-by: Akinobu Mita 
Tested-by: Per Forlin 
Cc: Jens Axboe 
Cc: Christoph Lameter 
Cc: Pekka Enberg 
Cc: Matt Mackall 
Cc: Randy Dunlap 
Cc: Stephen Rothwell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fault injection: correct function names in documentation

2010-02-03T02:11:22+00:00

init_fault_attr_entries() should be init_fault_attr_dentries().

cleanup_fault_attr_entries() should be cleanup_fault_attr_dentries().

Signed-off-by: Anton Blanchard 
Acked-by: Akinobu Mita 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

debugfs: Fix terminology inconsistency of dir name to mount debugfs filesystem.

2009-06-16T04:30:28+00:00

Many developers use "/debug/" or "/debugfs/" or "/sys/kernel/debug/"
directory name to mount debugfs filesystem for ftrace according to
./Documentation/tracers/ftrace.txt file.

And, three directory names(ex:/debug/, /debugfs/, /sys/kernel/debug/) is
existed in kernel source like ftrace, DRM, Wireless, Documentation,
Network[sky2]files to mount debugfs filesystem.

debugfs means debug filesystem for debugging easy to use by greg kroah
hartman. "/sys/kernel/debug/" name is suitable as directory name
of debugfs filesystem.
- debugfs related reference: http://lwn.net/Articles/334546/

Fix inconsistency of directory name to mount debugfs filesystem.

* From Steven Rostedt
  - find_debugfs() and tracing_files() in this patch.

Signed-off-by: GeunSik Lim 
Acked-by     : Inaky Perez-Gonzalez 
Reviewed-by  : Steven Rostedt 
Reviewed-by  : James Smart 
CC: Jiri Kosina 
CC: David Airlie 
CC: Peter Osterlund 
CC: Ananth N Mavinakayanahalli 
CC: Anil S Keshavamurthy 
CC: Masami Hiramatsu 
Signed-off-by: Greg Kroah-Hartman

fault-injection: fix example scripts in documentation

2007-07-16T16:05:45+00:00

Fix and cleanup example scripts in fault injection documentation.

1. Eliminate broken oops() shell function.

2. Fold failcmd.sh and failmodule.sh into example scripts. It makes
   the example scripts work independent of current working directory.

3. Set "space" parameter to 0 to start injecting errors immediately.

4. Use /sys/module//sections/.data as upper bound of
   .text section. Because some module doesn't have .exit.text section.

Signed-off-by: Akinobu Mita 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fault-injection: add min-order parameter to fail_page_alloc

2007-07-16T16:05:45+00:00

Limiting smaller allocation failures by fault injection helps to find real
possible bugs.  Because higher order allocations are likely to fail and
zero-order allocations are not likely to fail.

This patch adds min-order parameter to fail_page_alloc.  It specifies the
minimum page allocation order to be injected failures.

Signed-off-by: Akinobu Mita 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] fault-injection: Correct, disambiguate, and reformat documentation

2006-12-08T16:29:03+00:00

Correct, disambiguate, and reformat documentation.

Signed-off-by: Don Mullis 
Cc: Akinobu Mita 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds