[PATCH] fault injection: stacktrace filtering

This patch provides stacktrace filtering feature.

The stacktrace filter allows failing only for the caller you are
interested in.

For example someone may want to inject kmalloc() failures into
only e100 module. they want to inject not only direct kmalloc() call,
but also indirect allocation, too.

- e100_poll --> netif_receive_skb --> packet_rcv_spkt --> skb_clone
  --> kmem_cache_alloc

This patch enables to detect function calls like this by stacktrace
and inject failures. The script Documentaion/fault-injection/failmodule.sh
helps it.

The range of text section of loaded e100 is expected to be
[/sys/module/e100/sections/.text, /sys/module/e100/sections/.exit.text)

So failmodule.sh stores these values into /debug/failslab/address-start
and /debug/failslab/address-end. The maximum stacktrace depth is specified
by /debug/failslab/stacktrace-depth.

Please see the example that demonstrates how to inject slab allocation
failures only for a specific module
in Documentation/fault-injection/fault-injection.txt

[dwm@meer.net: reject failure if any caller lies within specified range]
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Don Mullis <dwm@meer.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 8 insertions, 4 deletions

diff --git a/Documentation/fault-injection/fault-injection.txt b/Documentation/fault-injection/fault-injection.txt
index cf075c20eda0..6d6e5ac5ea92 100644
--- a/Documentation/fault-injection/fault-injection.txt
+++ b/Documentation/fault-injection/fault-injection.txt
@@ -73,13 +73,17 @@ configuration of fault-injection capabilities.
         Any positive value limits failures to only processes indicated by
         /proc/<pid>/make-it-fail==1.
 
-- /debug/*/address-start:
-- /debug/*/address-end:
+- /debug/*/require-start:
+- /debug/*/require-end:
+- /debug/*/reject-start:
+- /debug/*/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 this range.
-        Default is [0,ULONG_MAX) (whole of virtual address space).
+        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/*/stacktrace-depth: