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Message-Id: <1158645051.2419.2.camel@localhost.localdomain> Date: Mon, 18 Sep 2006 22:50:51 -0700 From: Don Mullis <dwm@...r.net> To: Akinobu Mita <mita@...aclelinux.com> Cc: linux-kernel@...r.kernel.org, ak@...e.de, akpm@...l.org Subject: Re: [patch 1/8] documentation and scripts Add reference to similar functionality in drivers/md/faulty.c . Clarify debugfs descriptions. Add an entry for fault-injection to Documentation/kernel-parameters.txt . Signed-off-by: Don Mullis <dwm@...r.net> --- Documentation/fault-injection/fault-injection.txt | 85 ++++++++++------------ Documentation/kernel-parameters.txt | 7 + 2 files changed, 47 insertions(+), 45 deletions(-) Index: linux-2.6.17/Documentation/fault-injection/fault-injection.txt =================================================================== --- linux-2.6.17.orig/Documentation/fault-injection/fault-injection.txt +++ linux-2.6.17/Documentation/fault-injection/fault-injection.txt @@ -1,6 +1,9 @@ Fault injection capabilities infrastructure =========================================== +See also drivers/md/faulty.c . + + Available fault injection capabilities -------------------------------------- @@ -14,58 +17,49 @@ o fail_page_alloc o fail_make_request - injects disk IO errors on permitted devices by /sys/block/<device>/make-it-fail - or /sys/block/<device>/<partition>/make-it-fail. (generic_make_request()) + injects disk IO errors on permitted devices by + /sys/block/<device>/make-it-fail or + /sys/block/<device>/<partition>/make-it-fail. (generic_make_request()) Configure fault-injection capabilities behavior ----------------------------------------------- -Example for failslab: - o debugfs entries fault-inject-debugfs kernel module provides some debugfs entries for runtime -configuration for fault-injection capabilities. - -- /debug/failslab/probability: +configuration of fault-injection capabilities. - specifies how often it should fail in percent. +- /debug/*/probability: -- /debug/failslab/interval: - - specifies the interval of failures. - -- /debug/failslab/times: - - specifies how many times failures may happen at most. + likelihood of failure injection, in percent. -- /debug/failslab/space: +- /debug/*/interval: - specifies the size of free space where memory can be allocated - safely in bytes. + specifies the interval between failures, for calls to + should_fail() that pass all the other tests. -- /debug/failslab/process-filter: + Note that if you enable this, by setting interval>1, you will + probably want to set probability=100. - specifies whether the process filter is enabled or not. - It allows failing only permitted processes by /proc/<pid>/make-it-fail +- /debug/*/times: -- /debug/failslab/stacktrace-depth: - - specifies the maximum stacktrace depth walking allowed. - A value '0' means stacktrace filter is disabled. + specifies how many times failures may happen at most. + A value of -1 means "no limit". -- /debug/failslab/address-start: -- /debug/failslab/address-end: +- /debug/*/space: - specifies the range of virtual address. - It allows failing only if the stacktrace hits in this range. + specifies an initial resource "budget", decremented by "size" + on each call to should_fail(,size). Failure injection is + suppressed until "space" reaches zero. o Boot option In order to inject faults while debugfs is not available (early boot time), -We can use boot option. +use the boot option: -- failslab=<interval>,<probability>,<space>,<times> + failslab= + fail_page_alloc= + fail_make_request=<interval>,<probability>,<space>,<times> How to add new fault injection capability ----------------------------------------- @@ -77,44 +71,42 @@ o define the fault attributes DEFINE_FAULT_INJECTION(name); Please see the definition of struct fault_attr in fault-inject.h - for the detail. + for details. o provide the way to configure fault attributes - boot option - If you need to enable the fault injection capability ealier boot time, + 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); - module parameters - If the scope of the fault injection capability is limited by a kernel module, - It is better to provide module parameters to configure the member of fault - attributes. + 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. - debugfs entries failslab, fail_page_alloc, and fail_make_request use this way. - - But now there is no helper functions to provides debugfs entries for + But now there is no helper functions to provide debugfs entries for fault injection capabilities. Please refer to lib/fault-inject-debugfs.c to know how to do. And please try not to add new one into fault-inject-debugfs module. - - Because failslab, fail_page_alloc, and fail_make_request are used ealier - boot time before debugfs is available and the slab allocator, - the page allocator, and the block layer cannot be built as module. + Because failslab, fail_page_alloc, and fail_make_request are used from + boot time, before debugfs is available, the slab allocator, + the page allocator, and the block layer cannot be built as modules. o add a hook to insert failures should_fail() returns 1 when failures should happen. - should_fail(attr); + should_fail(attr,size); -Tests ------ +Application Examples +-------------------- o inject slab allocation failures into module init/cleanup code @@ -148,3 +140,6 @@ echo 25 > /debug/failslab/probability ------------------------------------------------------------------------------ + + + Index: linux-2.6.17/Documentation/kernel-parameters.txt =================================================================== --- linux-2.6.17.orig/Documentation/kernel-parameters.txt +++ linux-2.6.17/Documentation/kernel-parameters.txt @@ -544,6 +544,13 @@ running once the system is up. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog. Format: <io>[,<irq>] + failslab= + fail_page_alloc= + fail_make_request=[KNL] + General fault injection mechanism. + Format: <interval>,<probability>,<space>,<times> + See also /Documentation/fault-injection/. + fd_mcs= [HW,SCSI] See header of drivers/scsi/fd_mcs.c. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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