* [PATCH] sched/fair: avoid integer overflow warning for fair_server_period_max;
@ 2024-08-07 8:00 Arnd Bergmann
2024-08-07 10:00 ` Vincent Guittot
0 siblings, 1 reply; 3+ messages in thread
From: Arnd Bergmann @ 2024-08-07 8:00 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot
Cc: Arnd Bergmann, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Valentin Schneider, linux-kernel
From: Arnd Bergmann <arnd@arndb.de>
The clalculation of fair_server_period_max includes an integer overflow:
In file included from kernel/sched/build_utility.c:72:
kernel/sched/debug.c:341:57: error: integer overflow in expression of type 'long int' results in '-100663296' [-Werror=overflow]
341 | static unsigned long fair_server_period_max = (1 << 22) * NSEC_PER_USEC; /* ~4 seconds */
Avoids this by using an unsigned constant to start with.
Fixes: d741f297bcea ("sched/fair: Fair server interface")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
kernel/sched/debug.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 0148bc65d39c..242e7f264a0b 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -338,7 +338,7 @@ enum dl_param {
DL_PERIOD,
};
-static unsigned long fair_server_period_max = (1 << 22) * NSEC_PER_USEC; /* ~4 seconds */
+static unsigned long fair_server_period_max = (1u << 22) * NSEC_PER_USEC; /* ~4 seconds */
static unsigned long fair_server_period_min = (100) * NSEC_PER_USEC; /* 100 us */
static ssize_t sched_fair_server_write(struct file *filp, const char __user *ubuf,
--
2.39.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] sched/fair: avoid integer overflow warning for fair_server_period_max;
2024-08-07 8:00 [PATCH] sched/fair: avoid integer overflow warning for fair_server_period_max; Arnd Bergmann
@ 2024-08-07 10:00 ` Vincent Guittot
2024-08-07 10:39 ` Peter Zijlstra
0 siblings, 1 reply; 3+ messages in thread
From: Vincent Guittot @ 2024-08-07 10:00 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Ingo Molnar, Peter Zijlstra, Juri Lelli, Arnd Bergmann,
Dietmar Eggemann, Steven Rostedt, Ben Segall, Mel Gorman,
Valentin Schneider, linux-kernel, Dan Carpenter
Hi Arnd
On Wed, 7 Aug 2024 at 10:00, Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> The clalculation of fair_server_period_max includes an integer overflow:
>
> In file included from kernel/sched/build_utility.c:72:
> kernel/sched/debug.c:341:57: error: integer overflow in expression of type 'long int' results in '-100663296' [-Werror=overflow]
> 341 | static unsigned long fair_server_period_max = (1 << 22) * NSEC_PER_USEC; /* ~4 seconds */
>
> Avoids this by using an unsigned constant to start with.
Dan sent something similar
https://lore.kernel.org/lkml/a936b991-e464-4bdf-94ab-08e25d364986@stanley.mountain/
>
> Fixes: d741f297bcea ("sched/fair: Fair server interface")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> kernel/sched/debug.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> index 0148bc65d39c..242e7f264a0b 100644
> --- a/kernel/sched/debug.c
> +++ b/kernel/sched/debug.c
> @@ -338,7 +338,7 @@ enum dl_param {
> DL_PERIOD,
> };
>
> -static unsigned long fair_server_period_max = (1 << 22) * NSEC_PER_USEC; /* ~4 seconds */
> +static unsigned long fair_server_period_max = (1u << 22) * NSEC_PER_USEC; /* ~4 seconds */
> static unsigned long fair_server_period_min = (100) * NSEC_PER_USEC; /* 100 us */
>
> static ssize_t sched_fair_server_write(struct file *filp, const char __user *ubuf,
> --
> 2.39.2
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] sched/fair: avoid integer overflow warning for fair_server_period_max;
2024-08-07 10:00 ` Vincent Guittot
@ 2024-08-07 10:39 ` Peter Zijlstra
0 siblings, 0 replies; 3+ messages in thread
From: Peter Zijlstra @ 2024-08-07 10:39 UTC (permalink / raw)
To: Vincent Guittot
Cc: Arnd Bergmann, Ingo Molnar, Juri Lelli, Arnd Bergmann,
Dietmar Eggemann, Steven Rostedt, Ben Segall, Mel Gorman,
Valentin Schneider, linux-kernel, Dan Carpenter
On Wed, Aug 07, 2024 at 12:00:35PM +0200, Vincent Guittot wrote:
> Hi Arnd
>
> On Wed, 7 Aug 2024 at 10:00, Arnd Bergmann <arnd@kernel.org> wrote:
> >
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > The clalculation of fair_server_period_max includes an integer overflow:
> >
> > In file included from kernel/sched/build_utility.c:72:
> > kernel/sched/debug.c:341:57: error: integer overflow in expression of type 'long int' results in '-100663296' [-Werror=overflow]
> > 341 | static unsigned long fair_server_period_max = (1 << 22) * NSEC_PER_USEC; /* ~4 seconds */
> >
> > Avoids this by using an unsigned constant to start with.
>
> Dan sent something similar
> https://lore.kernel.org/lkml/a936b991-e464-4bdf-94ab-08e25d364986@stanley.mountain/
Right, tglx also pointed me at a report for this. Let me go queue Dan's
patch.
> >
> > Fixes: d741f297bcea ("sched/fair: Fair server interface")
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> > kernel/sched/debug.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> > index 0148bc65d39c..242e7f264a0b 100644
> > --- a/kernel/sched/debug.c
> > +++ b/kernel/sched/debug.c
> > @@ -338,7 +338,7 @@ enum dl_param {
> > DL_PERIOD,
> > };
> >
> > -static unsigned long fair_server_period_max = (1 << 22) * NSEC_PER_USEC; /* ~4 seconds */
> > +static unsigned long fair_server_period_max = (1u << 22) * NSEC_PER_USEC; /* ~4 seconds */
> > static unsigned long fair_server_period_min = (100) * NSEC_PER_USEC; /* 100 us */
> >
> > static ssize_t sched_fair_server_write(struct file *filp, const char __user *ubuf,
> > --
> > 2.39.2
> >
^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-08-07 8:00 [PATCH] sched/fair: avoid integer overflow warning for fair_server_period_max; Arnd Bergmann
2024-08-07 10:00 ` Vincent Guittot
2024-08-07 10:39 ` Peter Zijlstra
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