kernel/linux.git/lib/fault-inject.c, branch v4.14.304

fault-inject: fix wrong should_fail() decision in task context

2017-08-10T22:54:06+00:00

Commit 1203c8e6fb0a ("fault-inject: simplify access check for fail-nth") unintentionally broke a conditional statement in should_fail(). Any faults are not injected in the task context by the change when the systematic fault injection is not used. This change restores to the previous correct behaviour. Link: http://lkml.kernel.org/r/1501633700-3488-1-git-send-email-akinobu.mita@gmail.com Fixes: 1203c8e6fb0a ("fault-inject: simplify access check for fail-nth") Signed-off-by: Akinobu Mita Reported-by: Lu Fengqi Tested-by: Lu Fengqi Cc: Dmitry Vyukov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fault-inject: simplify access check for fail-nth

2017-07-14T22:05:13+00:00

The fail-nth file is created with 0666 and the access is permitted if and only if the task is current. This file is owned by the currnet user. So we can create it with 0644 and allow the owner to write it. This enables to watch the status of task->fail_nth from another processes. [akinobu.mita@gmail.com: don't convert unsigned type value as signed int] Link: http://lkml.kernel.org/r/1492444483-9239-1-git-send-email-akinobu.mita@gmail.com [akinobu.mita@gmail.com: avoid unwanted data race to task->fail_nth] Link: http://lkml.kernel.org/r/1499962492-8931-1-git-send-email-akinobu.mita@gmail.com Link: http://lkml.kernel.org/r/1491490561-10485-5-git-send-email-akinobu.mita@gmail.com Signed-off-by: Akinobu Mita Acked-by: Dmitry Vyukov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fault-inject: support systematic fault injection

2017-07-12T23:26:01+00:00

Add /proc/self/task//fail-nth file that allows failing 0-th, 1-st, 2-nd and so on calls systematically. Excerpt from the added documentation: "Write to this file of integer N makes N-th call in the current task fail (N is 0-based). Read from this file returns a single char 'Y' or 'N' that says if the fault setup with a previous write to this file was injected or not, and disables the fault if it wasn't yet injected. Note that this file enables all types of faults (slab, futex, etc). This setting takes precedence over all other generic settings like probability, interval, times, etc. But per-capability settings (e.g. fail_futex/ignore-private) take precedence over it. This feature is intended for systematic testing of faults in a single system call. See an example below" Why add a new setting: 1. Existing settings are global rather than per-task. So parallel testing is not possible. 2. attr->interval is close but it depends on attr->count which is non reset to 0, so interval does not work as expected. 3. Trying to model this with existing settings requires manipulations of all of probability, interval, times, space, task-filter and unexposed count and per-task make-it-fail files. 4. Existing settings are per-failure-type, and the set of failure types is potentially expanding. 5. make-it-fail can't be changed by unprivileged user and aggressive stress testing better be done from an unprivileged user. Similarly, this would require opening the debugfs files to the unprivileged user, as he would need to reopen at least times file (not possible to pre-open before dropping privs). The proposed interface solves all of the above (see the example). We want to integrate this into syzkaller fuzzer. A prototype has found 10 bugs in kernel in first day of usage: https://groups.google.com/forum/#!searchin/syzkaller/%22FAULT_INJECTION%22%7Csort:relevance I've made the current interface work with all types of our sandboxes. For setuid the secret sauce was prctl(PR_SET_DUMPABLE, 1, 0, 0, 0) to make /proc entries non-root owned. So I am fine with the current version of the code. [akpm@linux-foundation.org: fix build] Link: http://lkml.kernel.org/r/20170328130128.101773-1-dvyukov@google.com Signed-off-by: Dmitry Vyukov Cc: Akinobu Mita Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/fault-inject.c: use correct check for interrupts

2017-05-09T00:15:12+00:00

in_interrupt() also returns true when bh is disabled in task context. That's not what fail_task() wants to check. Use the new in_task() predicate that does the right thing. Link: http://lkml.kernel.org/r/20170321091805.140676-1-dvyukov@google.com Signed-off-by: Dmitry Vyukov Reviewed-by: Akinobu Mita Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fault-inject: fix inverted interval/probability values in printk

2015-10-23T08:55:10+00:00

interval displays the probability and vice versa. Fixes: 6adc4a22f20bb ("fault-inject: add ratelimit option") Acked-by: Akinobu Mita Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fault-inject: add ratelimit option

2014-12-13T20:42:52+00:00

Current debug levels are not optimal. Especially if one want to provoke big numbers of faults(broken device simulator) then any verbose level will produce giant numbers of identical logging messages. Let's add ratelimit parameter for that purpose. Signed-off-by: Dmitry Monakhov Acked-by: Akinobu Mita Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

debugfs: add get/set for atomic types

2013-06-03T20:55:01+00:00

debugfs currently lack the ability to create attributes that set/get atomic_t values. This patch adds support for this through a new debugfs_create_atomic_t() function. Signed-off-by: Seth Jennings Acked-by: Greg Kroah-Hartman Acked-by: Mel Gorman Acked-by: Rik van Riel Acked-by: Konrad Rzeszutek Wilk Signed-off-by: Greg Kroah-Hartman

lib/: rename random32() to prandom_u32()

2013-04-30T01:28:42+00:00

Use preferable function name which implies using a pseudo-random number generator. Signed-off-by: Akinobu Mita Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fault-inject: avoid call to random32() if fault injection is disabled

2012-06-20T21:39:36+00:00

After enabling CONFIG_FAILSLAB I noticed random32 in profiles even if slub fault injection wasn't enabled at runtime. should_fail forces a comparison against random32() even if probability is 0: if (attr->probability <= random32() % 100) return false; Add a check up front for probability == 0 and avoid all of the more complicated checks. Signed-off-by: Anton Blanchard Acked-by: Akinobu Mita Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib: reduce the use of module.h wherever possible

2012-03-07T20:04:04+00:00

For files only using THIS_MODULE and/or EXPORT_SYMBOL, map them onto including export.h -- or if the file isn't even using those, then just delete the include. Fix up any implicit include dependencies that were being masked by module.h along the way. Signed-off-by: Paul Gortmaker