From: Daniel Bristot de Oliveira bristot@redhat.com
mainline inclusion from mainline-v5.14-rc1 commit 19c3eaa72288ce161441dd6b74b765a094d73488 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I4G64B CVE: NA
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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/acd7cd6e7d56b798a298c3bc8139a390b3c4ab52.162498636...
Cc: Ingo Molnar mingo@redhat.com Cc: Daniel Bristot de Oliveira bristot@redhat.com Cc: Dan Carpenter dan.carpenter@oracle.com Cc: linux-kernel@vger.kernel.org Fixes: bce29ac9ce0b ("trace: Add osnoise tracer") Reported-by: Dan Carpenter dan.carpenter@oracle.com Signed-off-by: Daniel Bristot de Oliveira bristot@redhat.com Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Wang ShaoBo bobo.shaobowang@huawei.com Acked-by: Xie XiuQi xiexiuqi@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- kernel/trace/trace_osnoise.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index 93be0b918eb2..b4b07af1acbc 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -1073,15 +1073,16 @@ 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;
/*