mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-24 21:24:00 +08:00
5d0ffa2b84
Correct, disambiguate, and reformat documentation. Signed-off-by: Don Mullis <dwm@meer.net> Cc: Akinobu Mita <akinobu.mita@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
226 lines
5.7 KiB
Plaintext
226 lines
5.7 KiB
Plaintext
Fault injection capabilities infrastructure
|
|
===========================================
|
|
|
|
See also drivers/md/faulty.c and "every_nth" module option for scsi_debug.
|
|
|
|
|
|
Available fault injection capabilities
|
|
--------------------------------------
|
|
|
|
o failslab
|
|
|
|
injects slab allocation failures. (kmalloc(), kmem_cache_alloc(), ...)
|
|
|
|
o fail_page_alloc
|
|
|
|
injects page allocation failures. (alloc_pages(), get_free_pages(), ...)
|
|
|
|
o fail_make_request
|
|
|
|
injects disk IO errors on devices permitted by setting
|
|
/sys/block/<device>/make-it-fail or
|
|
/sys/block/<device>/<partition>/make-it-fail. (generic_make_request())
|
|
|
|
Configure fault-injection capabilities behavior
|
|
-----------------------------------------------
|
|
|
|
o debugfs entries
|
|
|
|
fault-inject-debugfs kernel module provides some debugfs entries for runtime
|
|
configuration of fault-injection capabilities.
|
|
|
|
- /debug/fail*/probability:
|
|
|
|
likelihood of failure injection, in percent.
|
|
Format: <percent>
|
|
|
|
Note that one-failure-per-hundred is a very high error rate
|
|
for some testcases. Consider setting probability=100 and configure
|
|
/debug/fail*/interval for such testcases.
|
|
|
|
- /debug/fail*/interval:
|
|
|
|
specifies the interval between failures, for calls to
|
|
should_fail() that pass all the other tests.
|
|
|
|
Note that if you enable this, by setting interval>1, you will
|
|
probably want to set probability=100.
|
|
|
|
- /debug/fail*/times:
|
|
|
|
specifies how many times failures may happen at most.
|
|
A value of -1 means "no limit".
|
|
|
|
- /debug/fail*/space:
|
|
|
|
specifies an initial resource "budget", decremented by "size"
|
|
on each call to should_fail(,size). Failure injection is
|
|
suppressed until "space" reaches zero.
|
|
|
|
- /debug/fail*/verbose
|
|
|
|
Format: { 0 | 1 | 2 }
|
|
specifies the verbosity of the messages when failure is
|
|
injected. '0' means no messages; '1' will print only a single
|
|
log line per failure; '2' will print a call trace too -- useful
|
|
to debug the problems revealed by fault injection.
|
|
|
|
- /debug/fail*/task-filter:
|
|
|
|
Format: { 'Y' | 'N' }
|
|
A value of 'N' disables filtering by process (default).
|
|
Any positive value limits failures to only processes indicated by
|
|
/proc/<pid>/make-it-fail==1.
|
|
|
|
- /debug/fail*/require-start:
|
|
- /debug/fail*/require-end:
|
|
- /debug/fail*/reject-start:
|
|
- /debug/fail*/reject-end:
|
|
|
|
specifies the range of virtual addresses tested during
|
|
stacktrace walking. Failure is injected only if some caller
|
|
in the walked stacktrace lies within the required range, and
|
|
none lies within the rejected range.
|
|
Default required range is [0,ULONG_MAX) (whole of virtual address space).
|
|
Default rejected range is [0,0).
|
|
|
|
- /debug/fail*/stacktrace-depth:
|
|
|
|
specifies the maximum stacktrace depth walked during search
|
|
for a caller within [require-start,require-end) OR
|
|
[reject-start,reject-end).
|
|
|
|
- /debug/fail_page_alloc/ignore-gfp-highmem:
|
|
|
|
Format: { 'Y' | 'N' }
|
|
default is 'N', setting it to 'Y' won't inject failures into
|
|
highmem/user allocations.
|
|
|
|
- /debug/failslab/ignore-gfp-wait:
|
|
- /debug/fail_page_alloc/ignore-gfp-wait:
|
|
|
|
Format: { 'Y' | 'N' }
|
|
default is 'N', setting it to 'Y' will inject failures
|
|
only into non-sleep allocations (GFP_ATOMIC allocations).
|
|
|
|
o Boot option
|
|
|
|
In order to inject faults while debugfs is not available (early boot time),
|
|
use the boot option:
|
|
|
|
failslab=
|
|
fail_page_alloc=
|
|
fail_make_request=<interval>,<probability>,<space>,<times>
|
|
|
|
How to add new fault injection capability
|
|
-----------------------------------------
|
|
|
|
o #include <linux/fault-inject.h>
|
|
|
|
o define the fault attributes
|
|
|
|
DECLARE_FAULT_INJECTION(name);
|
|
|
|
Please see the definition of struct fault_attr in fault-inject.h
|
|
for details.
|
|
|
|
o provide a way to configure fault attributes
|
|
|
|
- boot option
|
|
|
|
If you need to enable the fault injection capability from boot time, you can
|
|
provide boot option to configure it. There is a helper function for it:
|
|
|
|
setup_fault_attr(attr, str);
|
|
|
|
- debugfs entries
|
|
|
|
failslab, fail_page_alloc, and fail_make_request use this way.
|
|
Helper functions:
|
|
|
|
init_fault_attr_entries(entries, attr, name);
|
|
void cleanup_fault_attr_entries(entries);
|
|
|
|
- module parameters
|
|
|
|
If the scope of the fault injection capability is limited to a
|
|
single kernel module, it is better to provide module parameters to
|
|
configure the fault attributes.
|
|
|
|
o add a hook to insert failures
|
|
|
|
Upon should_fail() returning true, client code should inject a failure.
|
|
|
|
should_fail(attr, size);
|
|
|
|
Application Examples
|
|
--------------------
|
|
|
|
o inject slab allocation failures into module init/cleanup code
|
|
|
|
------------------------------------------------------------------------------
|
|
#!/bin/bash
|
|
|
|
FAILCMD=Documentation/fault-injection/failcmd.sh
|
|
BLACKLIST="root_plug evbug"
|
|
|
|
FAILNAME=failslab
|
|
echo Y > /debug/$FAILNAME/task-filter
|
|
echo 10 > /debug/$FAILNAME/probability
|
|
echo 100 > /debug/$FAILNAME/interval
|
|
echo -1 > /debug/$FAILNAME/times
|
|
echo 2 > /debug/$FAILNAME/verbose
|
|
echo 1 > /debug/$FAILNAME/ignore-gfp-wait
|
|
|
|
blacklist()
|
|
{
|
|
echo $BLACKLIST | grep $1 > /dev/null 2>&1
|
|
}
|
|
|
|
oops()
|
|
{
|
|
dmesg | grep BUG > /dev/null 2>&1
|
|
}
|
|
|
|
find /lib/modules/`uname -r` -name '*.ko' -exec basename {} .ko \; |
|
|
while read i
|
|
do
|
|
oops && exit 1
|
|
|
|
if ! blacklist $i
|
|
then
|
|
echo inserting $i...
|
|
bash $FAILCMD modprobe $i
|
|
fi
|
|
done
|
|
|
|
lsmod | awk '{ if ($3 == 0) { print $1 } }' |
|
|
while read i
|
|
do
|
|
oops && exit 1
|
|
|
|
if ! blacklist $i
|
|
then
|
|
echo removing $i...
|
|
bash $FAILCMD modprobe -r $i
|
|
fi
|
|
done
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
o inject slab allocation failures only for a specific module
|
|
|
|
------------------------------------------------------------------------------
|
|
#!/bin/bash
|
|
|
|
FAILMOD=Documentation/fault-injection/failmodule.sh
|
|
|
|
echo injecting errors into the module $1...
|
|
|
|
modprobe $1
|
|
bash $FAILMOD failslab $1 10
|
|
echo 25 > /debug/failslab/probability
|
|
|
|
------------------------------------------------------------------------------
|
|
|