From: Colin Ian King <[email protected]>
The less than zero comparison of the u64 variable 'noise' is always
false because the variable is unsigned. Since the time_sub macro
can potentially return an -ve vale, make the variable a s64 to
fix the issue.
Addresses-Coverity: ("Unsigned compared against 0")
Fixes: bce29ac9ce0b ("trace: Add osnoise tracer")
Signed-off-by: Colin Ian King <[email protected]>
---
kernel/trace/trace_osnoise.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index 38aa5e208ffd..02c984560ceb 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -1040,11 +1040,11 @@ 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;
+ u64 sum_noise = 0, max_noise = 0;
struct trace_array *tr = osnoise_trace;
u64 start, sample, last_sample;
u64 last_int_count, int_count;
- s64 total, last_total = 0;
+ s64 noise = 0, total, last_total = 0;
struct osnoise_sample s;
unsigned int threshold;
int hw_count = 0;
--
2.31.1
On 6/29/21 6:52 PM, Colin King wrote:
> From: Colin Ian King <[email protected]>
>
> The less than zero comparison of the u64 variable 'noise' is always
> false because the variable is unsigned. Since the time_sub macro
> can potentially return an -ve vale, make the variable a s64 to
> fix the issue.
Ops! concurrent bug fixing.
Dan Carpenter reported the same bug (and another problem), and I was working in
the patches... I saw yours after sending his ones:
https://lore.kernel.org/lkml/acd7cd6e7d56b798a298c3bc8139a390b3c4ab52.1624986368.git.bristot@redhat.com/
The patches do the same fix, but there it also:
- Made also max_noise s64 (it is snapshot of noise).
- Arranged the declarations in the inverted christmas tree.
> Addresses-Coverity: ("Unsigned compared against 0")
> Fixes: bce29ac9ce0b ("trace: Add osnoise tracer")
> Signed-off-by: Colin Ian King <[email protected]>
Steven, can we merge the flags?
-- Daniel
> ---
> kernel/trace/trace_osnoise.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
> index 38aa5e208ffd..02c984560ceb 100644
> --- a/kernel/trace/trace_osnoise.c
> +++ b/kernel/trace/trace_osnoise.c
> @@ -1040,11 +1040,11 @@ 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;
> + u64 sum_noise = 0, max_noise = 0;
> struct trace_array *tr = osnoise_trace;
> u64 start, sample, last_sample;
> u64 last_int_count, int_count;
> - s64 total, last_total = 0;
> + s64 noise = 0, total, last_total = 0;
> struct osnoise_sample s;
> unsigned int threshold;
> int hw_count = 0;
>
On 29/06/2021 18:19, Daniel Bristot de Oliveira wrote:
> On 6/29/21 6:52 PM, Colin King wrote:
>> From: Colin Ian King <[email protected]>
>>
>> The less than zero comparison of the u64 variable 'noise' is always
>> false because the variable is unsigned. Since the time_sub macro
>> can potentially return an -ve vale, make the variable a s64 to
>> fix the issue.
>
> Ops! concurrent bug fixing.
Well, shows static analysis is doing it's thing and I'm not being
vigilant enough by spotting that Dan found it earlier :-)
>
> Dan Carpenter reported the same bug (and another problem), and I was working in
> the patches... I saw yours after sending his ones:
>
> https://lore.kernel.org/lkml/acd7cd6e7d56b798a298c3bc8139a390b3c4ab52.1624986368.git.bristot@redhat.com/
>
> The patches do the same fix, but there it also:
>
> - Made also max_noise s64 (it is snapshot of noise).
> - Arranged the declarations in the inverted christmas tree.
>
>> Addresses-Coverity: ("Unsigned compared against 0")
>> Fixes: bce29ac9ce0b ("trace: Add osnoise tracer")
>> Signed-off-by: Colin Ian King <[email protected]>
>
> Steven, can we merge the flags?
>
> -- Daniel
>
>> ---
>> kernel/trace/trace_osnoise.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
>> index 38aa5e208ffd..02c984560ceb 100644
>> --- a/kernel/trace/trace_osnoise.c
>> +++ b/kernel/trace/trace_osnoise.c
>> @@ -1040,11 +1040,11 @@ 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;
>> + u64 sum_noise = 0, max_noise = 0;
>> struct trace_array *tr = osnoise_trace;
>> u64 start, sample, last_sample;
>> u64 last_int_count, int_count;
>> - s64 total, last_total = 0;
>> + s64 noise = 0, total, last_total = 0;
>> struct osnoise_sample s;
>> unsigned int threshold;
>> int hw_count = 0;
>>
>
On Tue, Jun 29, 2021 at 06:21:32PM +0100, Colin Ian King wrote:
> On 29/06/2021 18:19, Daniel Bristot de Oliveira wrote:
> > On 6/29/21 6:52 PM, Colin King wrote:
> >> From: Colin Ian King <[email protected]>
> >>
> >> The less than zero comparison of the u64 variable 'noise' is always
> >> false because the variable is unsigned. Since the time_sub macro
> >> can potentially return an -ve vale, make the variable a s64 to
> >> fix the issue.
> >
> > Ops! concurrent bug fixing.
>
> Well, shows static analysis is doing it's thing and I'm not being
> vigilant enough by spotting that Dan found it earlier :-)
Nah. I don't normally CC kernel-janitors on bug reports. I sometimes
do on netdev stuff because Dave told me ten years ago that static
analysis noise on the list was an annoying thing. And actually on that
one I didn't CC anyone actually, Oops.
regards,
dan carpenter
On Tue, 29 Jun 2021 19:19:25 +0200
Daniel Bristot de Oliveira <[email protected]> wrote:
> > Addresses-Coverity: ("Unsigned compared against 0")
> > Fixes: bce29ac9ce0b ("trace: Add osnoise tracer")
> > Signed-off-by: Colin Ian King <[email protected]>
>
> Steven, can we merge the flags?
I don't usually do that. I just take the first patch that I apply.
This isn't that complex of a patch, do we need to do this?
-- Steve
On 6/30/21 3:05 PM, Steven Rostedt wrote:
> On Tue, 29 Jun 2021 19:19:25 +0200
> Daniel Bristot de Oliveira <[email protected]> wrote:
>
>>> Addresses-Coverity: ("Unsigned compared against 0")
>>> Fixes: bce29ac9ce0b ("trace: Add osnoise tracer")
>>> Signed-off-by: Colin Ian King <[email protected]>
>> Steven, can we merge the flags?
> I don't usually do that.
Ack!
-- Daniel