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-rw-r--r--Documentation/fault-injection/fault-injection.txt70
1 files changed, 35 insertions, 35 deletions
diff --git a/Documentation/fault-injection/fault-injection.txt b/Documentation/fault-injection/fault-injection.txt
index 6d6e5ac5ea92..b7ca560b9340 100644
--- a/Documentation/fault-injection/fault-injection.txt
+++ b/Documentation/fault-injection/fault-injection.txt
@@ -17,7 +17,7 @@ o fail_page_alloc
o fail_make_request
- injects disk IO errors on permitted devices by
+ 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())
@@ -29,16 +29,16 @@ o debugfs entries
fault-inject-debugfs kernel module provides some debugfs entries for runtime
configuration of fault-injection capabilities.
-- /debug/*/probability:
+- /debug/fail*/probability:
likelihood of failure injection, in percent.
Format: <percent>
- Note that one-failure-per-handred is a very high error rate
- for some testcases. Please set probably=100 and configure
- /debug/*/interval for such testcases.
+ 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/*/interval:
+- /debug/fail*/interval:
specifies the interval between failures, for calls to
should_fail() that pass all the other tests.
@@ -46,37 +46,36 @@ configuration of fault-injection capabilities.
Note that if you enable this, by setting interval>1, you will
probably want to set probability=100.
-- /debug/*/times:
+- /debug/fail*/times:
specifies how many times failures may happen at most.
A value of -1 means "no limit".
-- /debug/*/space:
+- /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/*/verbose
+- /debug/fail*/verbose
Format: { 0 | 1 | 2 }
- specifies the verbosity of the messages when failure is injected.
- We default to 0 (no extra messages), setting it to '1' will
- print only to tell failure happened, '2' will print call trace too -
- it is useful to debug the problems revealed by fault injection
- capabilities.
+ 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/*/task-filter:
+- /debug/fail*/task-filter:
- Format: { 0 | 1 }
- A value of '0' disables filtering by process (default).
+ 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/*/require-start:
-- /debug/*/require-end:
-- /debug/*/reject-start:
-- /debug/*/reject-end:
+- /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
@@ -85,22 +84,23 @@ configuration of fault-injection capabilities.
Default required range is [0,ULONG_MAX) (whole of virtual address space).
Default rejected range is [0,0).
-- /debug/*/stacktrace-depth:
+- /debug/fail*/stacktrace-depth:
specifies the maximum stacktrace depth walked during search
- for a caller within [address-start,address-end).
+ for a caller within [require-start,require-end) OR
+ [reject-start,reject-end).
- /debug/fail_page_alloc/ignore-gfp-highmem:
- Format: { 0 | 1 }
- default is 0, setting it to '1' won't inject failures into
+ 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: { 0 | 1 }
- default is 0, setting it to '1' will inject failures
+ Format: { 'Y' | 'N' }
+ default is 'N', setting it to 'Y' will inject failures
only into non-sleep allocations (GFP_ATOMIC allocations).
o Boot option
@@ -124,22 +124,22 @@ o define the fault attributes
Please see the definition of struct fault_attr in fault-inject.h
for details.
-o provide the way to configure fault attributes
+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.
+ provide boot option to configure it. There is a helper function for it:
- setup_fault_attr(attr, str);
+ setup_fault_attr(attr, str);
- debugfs entries
failslab, fail_page_alloc, and fail_make_request use this way.
- There is a helper function for it.
+ Helper functions:
- init_fault_attr_entries(entries, attr, name);
- void cleanup_fault_attr_entries(entries);
+ init_fault_attr_entries(entries, attr, name);
+ void cleanup_fault_attr_entries(entries);
- module parameters
@@ -149,9 +149,9 @@ o provide the way to configure fault attributes
o add a hook to insert failures
- should_fail() returns 1 when failures should happen.
+ Upon should_fail() returning true, client code should inject a failure.
- should_fail(attr,size);
+ should_fail(attr, size);
Application Examples
--------------------