From 19c3eaa72288ce161441dd6b74b765a094d73488 Mon Sep 17 00:00:00 2001 From: Daniel Bristot de Oliveira Date: Tue, 29 Jun 2021 19:10:26 +0200 Subject: trace/osnoise: Make 'noise' variable s64 in run_osnoise() Dab Carpenter reported that: The patch bce29ac9ce0b: "trace: Add osnoise tracer" from Jun 22, 2021, leads to the following static checker warning: kernel/trace/trace_osnoise.c:1103 run_osnoise() warn: unsigned 'noise' is never less than zero. In this part of the code: 1100 /* 1101 * This shouldn't happen. 1102 */ 1103 if (noise < 0) { ^^^^^^^^^ 1104 osnoise_taint("negative noise!"); 1105 goto out; 1106 } 1107 And the static checker is right because 'noise' is u64. Make noise s64 and keep the check. It is important to check if the time read is behaving correctly - so we can trust the results. I also re-arranged some variable declarations. Link: https://lkml.kernel.org/r/acd7cd6e7d56b798a298c3bc8139a390b3c4ab52.1624986368.git.bristot@redhat.com Cc: Ingo Molnar Cc: Daniel Bristot de Oliveira Cc: Dan Carpenter Cc: linux-kernel@vger.kernel.org Fixes: bce29ac9ce0b ("trace: Add osnoise tracer") Reported-by: Dan Carpenter Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_osnoise.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index 085a83de98ad..cc1faca1a620 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -1042,15 +1042,16 @@ static void osnoise_stop_tracing(void) static int run_osnoise(void) { struct osnoise_variables *osn_var = this_cpu_osn_var(); - u64 noise = 0, sum_noise = 0, max_noise = 0; struct trace_array *tr = osnoise_trace; u64 start, sample, last_sample; u64 last_int_count, int_count; + s64 noise = 0, max_noise = 0; s64 total, last_total = 0; struct osnoise_sample s; unsigned int threshold; - int hw_count = 0; u64 runtime, stop_in; + u64 sum_noise = 0; + int hw_count = 0; int ret = -1; /* -- cgit v1.2.3