On Mon, Jun 8, 2026 at 9:03 PM Steven Rostedt <[email protected]> wrote: > > On Tue, 9 Jun 2026 00:44:23 +0000 > Samuel Moelius <[email protected]> wrote: > > > The ftrace-ops sample exposes nr_function_calls as a module parameter > > and uses it as the divisor when printing the measured time per call. > > Loading the module with nr_function_calls=0 skips the benchmark loop and > > then divides the elapsed time by zero, crashing the kernel during sample > > module initialization. > > This change is rather pointless, but whatever. > > > > > Reject a zero call count before registering any ftrace ops. > > > > Assisted-by: Codex:gpt-5.5-cyber-preview > > Signed-off-by: Samuel Moelius <[email protected]> > > --- > > samples/ftrace/ftrace-ops.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/samples/ftrace/ftrace-ops.c b/samples/ftrace/ftrace-ops.c > > index 68d6685c80bd..d5adaa61484f 100644 > > --- a/samples/ftrace/ftrace-ops.c > > +++ b/samples/ftrace/ftrace-ops.c > > @@ -190,6 +190,11 @@ static int __init ftrace_ops_sample_init(void) > > tracer_irrelevant = ops_func_count; > > } > > > > + if (!nr_function_calls) { > > + pr_err("nr_function_calls must be non-zero\n"); > > + return -EINVAL; > > No need to print that the admin did something stupid. > > > + } > > + > > pr_info("registering:\n" > > " relevant ops: %u\n" > > " tracee: %ps\n" > > In fact, I would just change the output to be: > > pr_info("Attempted %u calls to %ps in %lluns (%lluns / call)\n", > nr_function_calls, tracee_relevant, > period, nr_function_calls ? div_u64(period, > nr_function_calls) : -1LL); > > and have garbage in, garbage out.
Is it okay to keep the same subject line or should I change it?
