fault-injection: make stacktrace filter works as expected

stacktrace filter is checked after others, such as fail-nth, interval and
probability.  This make it doesn't work well as expected.

Fix to running stacktrace filter before other filters.  It will speed up
fault inject testing for driver modules.

Link: https://lkml.kernel.org/r/20220817080332.1052710-5-weiyongjun1@huawei.com
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Isabella Basso <isabbasso@riseup.net>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/lib/fault-inject.c b/lib/fault-inject.c
index d7819cacf8901bc6866f6b4d1a439c8d03dd5af1..6cff320c4eb4085b0dc93cb43909cb4fce8fac94 100644 (file)
--- a/lib/fault-inject.c
+++ b/lib/fault-inject.c
@@ -102,10 +102,16 @@ static inline bool fail_stacktrace(struct fault_attr *attr)
 
 bool should_fail_ex(struct fault_attr *attr, ssize_t size, int flags)
 {
+       bool stack_checked = false;
+
        if (in_task()) {
                unsigned int fail_nth = READ_ONCE(current->fail_nth);
 
                if (fail_nth) {
+                       if (!fail_stacktrace(attr))
+                               return false;
+
+                       stack_checked = true;
                        fail_nth--;
                        WRITE_ONCE(current->fail_nth, fail_nth);
                        if (!fail_nth)
@@ -125,6 +131,9 @@ bool should_fail_ex(struct fault_attr *attr, ssize_t size, int flags)
        if (atomic_read(&attr->times) == 0)
                return false;
 
+       if (!stack_checked && !fail_stacktrace(attr))
+               return false;
+
        if (atomic_read(&attr->space) > size) {
                atomic_sub(size, &attr->space);
                return false;
@@ -139,9 +148,6 @@ bool should_fail_ex(struct fault_attr *attr, ssize_t size, int flags)
        if (attr->probability <= get_random_u32_below(100))
                return false;
 
-       if (!fail_stacktrace(attr))
-               return false;
-
 fail:
        if (!(flags & FAULT_NOWARN))
                fail_dump(attr);