Signed-off-by: Daniel Santos <daniel.santos@pobox.com> --- src/thread/__timedwait.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/thread/__timedwait.c b/src/thread/__timedwait.c index 666093be..9829b93e 100644 --- a/src/thread/__timedwait.c +++ b/src/thread/__timedwait.c @@ -38,7 +38,7 @@ int __timedwait_cp(volatile int *addr, int val, if (priv) priv = FUTEX_PRIVATE; if (at) { - if (at->tv_nsec >= 1000000000UL) return EINVAL; + if ((unsigned long)at->tv_nsec >= 1000000000UL) return EINVAL; if (__clock_gettime(clk, &to)) return EINVAL; to.tv_sec = at->tv_sec - to.tv_sec; if ((to.tv_nsec = at->tv_nsec - to.tv_nsec) < 0) { -- 2.24.1
On 6/24/20 4:20 PM, Daniel Santos wrote:
> Signed-off-by: Daniel Santos <daniel.santos@pobox.com>
> ---
> src/thread/__timedwait.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/thread/__timedwait.c b/src/thread/__timedwait.c
> index 666093be..9829b93e 100644
> --- a/src/thread/__timedwait.c
> +++ b/src/thread/__timedwait.c
> @@ -38,7 +38,7 @@ int __timedwait_cp(volatile int *addr, int val,
> if (priv) priv = FUTEX_PRIVATE;
>
> if (at) {
> - if (at->tv_nsec >= 1000000000UL) return EINVAL;
> + if ((unsigned long)at->tv_nsec >= 1000000000UL) return EINVAL;
> if (__clock_gettime(clk, &to)) return EINVAL;
> to.tv_sec = at->tv_sec - to.tv_sec;
> if ((to.tv_nsec = at->tv_nsec - to.tv_nsec) < 0) {
>
may be use < 0 || >= 1000000000L and avoid the cast.
there is a similar issue in src/thread/pthread_cond_timedwait.c as well
On Thu, Jun 25, 2020 at 08:58:41AM -0700, Khem Raj wrote:
>
>
> On 6/24/20 4:20 PM, Daniel Santos wrote:
> > Signed-off-by: Daniel Santos <daniel.santos@pobox.com>
> > ---
> > src/thread/__timedwait.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/src/thread/__timedwait.c b/src/thread/__timedwait.c
> > index 666093be..9829b93e 100644
> > --- a/src/thread/__timedwait.c
> > +++ b/src/thread/__timedwait.c
> > @@ -38,7 +38,7 @@ int __timedwait_cp(volatile int *addr, int val,
> > if (priv) priv = FUTEX_PRIVATE;
> >
> > if (at) {
> > - if (at->tv_nsec >= 1000000000UL) return EINVAL;
> > + if ((unsigned long)at->tv_nsec >= 1000000000UL) return EINVAL;
> > if (__clock_gettime(clk, &to)) return EINVAL;
> > to.tv_sec = at->tv_sec - to.tv_sec;
> > if ((to.tv_nsec = at->tv_nsec - to.tv_nsec) < 0) {
> >
> may be use < 0 || >= 1000000000L and avoid the cast.
> there is a similar issue in src/thread/pthread_cond_timedwait.c as well
This is not a bug but intentional usage of the language.
On 6/25/20 10:58 AM, Khem Raj wrote: > > On 6/24/20 4:20 PM, Daniel Santos wrote: >> Signed-off-by: Daniel Santos <daniel.santos@pobox.com> >> --- >> src/thread/__timedwait.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/src/thread/__timedwait.c b/src/thread/__timedwait.c >> index 666093be..9829b93e 100644 >> --- a/src/thread/__timedwait.c >> +++ b/src/thread/__timedwait.c >> @@ -38,7 +38,7 @@ int __timedwait_cp(volatile int *addr, int val, >> if (priv) priv = FUTEX_PRIVATE; >> >> if (at) { >> - if (at->tv_nsec >= 1000000000UL) return EINVAL; >> + if ((unsigned long)at->tv_nsec >= 1000000000UL) return EINVAL; >> if (__clock_gettime(clk, &to)) return EINVAL; >> to.tv_sec = at->tv_sec - to.tv_sec; >> if ((to.tv_nsec = at->tv_nsec - to.tv_nsec) < 0) { >> > may be use < 0 || >= 1000000000L and avoid the cast. > there is a similar issue in src/thread/pthread_cond_timedwait.c as well Thank you for that. I'll resubmit changing both instances. In this case, the POSIX spec requires nt_nsec to be a long ( https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/time.h.html ). Either way, a good optimizer should convert this into an unsigned compare. My early years in 6502 assembly sort-of shapes my thinking, as I try to write higher level code as similarly to the assembly I presume the compiler will emit. But if the project has a strong preference to avoid casts, I can change it. Thanks! Daniel
On Fri, Jun 26, 2020 at 2:20 AM Daniel Santos <daniel@gsat.us> wrote:
>
> ...
> >> if (at) {
> >> - if (at->tv_nsec >= 1000000000UL) return EINVAL;
> >> + if ((unsigned long)at->tv_nsec >= 1000000000UL) return EINVAL;
> >> if (__clock_gettime(clk, &to)) return EINVAL;
> >> to.tv_sec = at->tv_sec - to.tv_sec;
> >> if ((to.tv_nsec = at->tv_nsec - to.tv_nsec) < 0) {
> >>
> > may be use < 0 || >= 1000000000L and avoid the cast.
> > there is a similar issue in src/thread/pthread_cond_timedwait.c as well
> Thank you for that. I'll resubmit changing both instances.
>
> In this case, the POSIX spec requires nt_nsec to be a long (
> https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/time.h.html
> ). Either way, a good optimizer should convert this into an unsigned
I believe the C language says the signed value gets promoted to an
unsigned value. I don't believe the optimizer has anything to do with
it.
That's why -1 is greater than 1 in C:
int x = -1;
unsigned int y = 1;
if (x > y)
printf("WTF???\n");
Jeff
On 6/26/20 1:26 AM, Jeffrey Walton wrote:
> On Fri, Jun 26, 2020 at 2:20 AM Daniel Santos <daniel@gsat.us> wrote:
>> ...
>>>> if (at) {
>>>> - if (at->tv_nsec >= 1000000000UL) return EINVAL;
>>>> + if ((unsigned long)at->tv_nsec >= 1000000000UL) return EINVAL;
>>>> if (__clock_gettime(clk, &to)) return EINVAL;
>>>> to.tv_sec = at->tv_sec - to.tv_sec;
>>>> if ((to.tv_nsec = at->tv_nsec - to.tv_nsec) < 0) {
>>>>
>>> may be use < 0 || >= 1000000000L and avoid the cast.
>>> there is a similar issue in src/thread/pthread_cond_timedwait.c as well
>> Thank you for that. I'll resubmit changing both instances.
>>
>> In this case, the POSIX spec requires nt_nsec to be a long (
>> https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/time.h.html
>> ). Either way, a good optimizer should convert this into an unsigned
> I believe the C language says the signed value gets promoted to an
> unsigned value. I don't believe the optimizer has anything to do with
> it.
>
> That's why -1 is greater than 1 in C:
>
> int x = -1;
> unsigned int y = 1;
> if (x > y)
> printf("WTF???\n");
>
> Jeff
Yes, I was referring to Khem's suggestion:
may be use < 0 || >= 1000000000L and avoid the cast.
The optimizer should convert this into a single unsigned compare on just
about any modern processor (e.g., two's compliment).
I suppose the real solution is to not add -Wextra to CFLAGS unless you
add -Wno-sign-compare, as musl intentionally uses this promotion rule.
Thanks!
Daniel