On Tue, Sep 27, 2022 at 12:05 PM David Matlack <dmatlack@xxxxxxxxxx> wrote: > > Bail out of test_dump_stack() if the stack trace is empty rather than > invoking addr2line with zero addresses. The problem with the latter is > that addr2line will block waiting for addresses to be passed in via > stdin, e.g. if running a selftest from an interactive terminal. > > Opportunistically fix up the comment that mentions skipping 3 frames > since only 2 are skipped in the code, and move the call to backtrace() > down to where it is used. > > Cc: Vipin Sharma <vipinsh@xxxxxxxxxx> > Cc: Sean Christopherson <seanjc@xxxxxxxxxx> > Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx> > --- > v2: > - Move backtrace() down to where it is used [Vipin] > - Change "stack trace empty" to "stack trace missing" [me] > > v1: https://lore.kernel.org/kvm/20220922231724.3560211-1-dmatlack@xxxxxxxxxx/ > > tools/testing/selftests/kvm/lib/assert.c | 15 +++++++++++---- > 1 file changed, 11 insertions(+), 4 deletions(-) > > diff --git a/tools/testing/selftests/kvm/lib/assert.c b/tools/testing/selftests/kvm/lib/assert.c > index 71ade6100fd3..7b92d1aaeda6 100644 > --- a/tools/testing/selftests/kvm/lib/assert.c > +++ b/tools/testing/selftests/kvm/lib/assert.c > @@ -38,16 +38,23 @@ static void test_dump_stack(void) > 1]; > char *c; > > - n = backtrace(stack, n); > c = &cmd[0]; > c += sprintf(c, "%s", addr2line); > + > /* > - * Skip the first 3 frames: backtrace, test_dump_stack, and > - * test_assert. We hope that backtrace isn't inlined and the other two > - * we've declared noinline. > + * Skip the first 2 frames, which should be test_dump_stack() and > + * test_assert(); both of which are declared noinline. Bail if the > + * resulting stack trace would be empty. Otherwise, addr2line will block > + * waiting for addresses to be passed in via stdin. > */ > + n = backtrace(stack, n); > + if (n <= 2) { > + fputs(" (stack trace missing)\n", stderr); > + return; > + } > for (i = 2; i < n; i++) > c += sprintf(c, " %lx", ((unsigned long) stack[i]) - 1); > + > c += sprintf(c, "%s", pipeline); > #pragma GCC diagnostic push > #pragma GCC diagnostic ignored "-Wunused-result" > > base-commit: 372d07084593dc7a399bf9bee815711b1fb1bcf2 > prerequisite-patch-id: 2e3661ba8856c29b769499bac525b6943d9284b8 > prerequisite-patch-id: 1a148d98d96d73a520ed070260608ddf1bdd0f08 > -- > 2.37.3.998.g577e59143f-goog > Reviewed-by: Vipin Sharma <vipinsh@xxxxxxxxxx>
