* [PATCH v2] fix clock_nanosleep error case
@ 2016-09-17 16:05 Daniel Sabogal
2016-09-18 3:38 ` Rich Felker
2016-10-20 5:47 ` Rich Felker
0 siblings, 2 replies; 5+ messages in thread
From: Daniel Sabogal @ 2016-09-17 16:05 UTC (permalink / raw)
To: musl
posix requires that EINVAL be returned if the first parameter specifies
the cpu-time clock of the calling thread (CLOCK_THREAD_CPUTIME_ID).
linux returns ENOTSUP instead so we handle this.
---
Applied Szabolcs' suggestion for remapping the return value.
clock_nanosleep is required to be a cancellation point.
---
src/time/clock_nanosleep.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/src/time/clock_nanosleep.c b/src/time/clock_nanosleep.c
index ec87b9e..9e4d9f1 100644
--- a/src/time/clock_nanosleep.c
+++ b/src/time/clock_nanosleep.c
@@ -1,8 +1,10 @@
#include <time.h>
+#include <errno.h>
#include "syscall.h"
#include "libc.h"
int clock_nanosleep(clockid_t clk, int flags, const struct timespec *req, struct timespec *rem)
{
- return -__syscall_cp(SYS_clock_nanosleep, clk, flags, req, rem);
+ int r = -__syscall_cp(SYS_clock_nanosleep, clk, flags, req, rem);
+ return clk == CLOCK_THREAD_CPUTIME_ID ? EINVAL : r;
}
--
2.10.0
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] fix clock_nanosleep error case
2016-09-17 16:05 [PATCH v2] fix clock_nanosleep error case Daniel Sabogal
@ 2016-09-18 3:38 ` Rich Felker
2016-09-18 19:01 ` Daniel Sabogal
2016-10-20 5:47 ` Rich Felker
1 sibling, 1 reply; 5+ messages in thread
From: Rich Felker @ 2016-09-18 3:38 UTC (permalink / raw)
To: Daniel Sabogal; +Cc: musl
On Sat, Sep 17, 2016 at 12:05:45PM -0400, Daniel Sabogal wrote:
> posix requires that EINVAL be returned if the first parameter specifies
> the cpu-time clock of the calling thread (CLOCK_THREAD_CPUTIME_ID).
> linux returns ENOTSUP instead so we handle this.
> ---
> Applied Szabolcs' suggestion for remapping the return value.
> clock_nanosleep is required to be a cancellation point.
> ---
> src/time/clock_nanosleep.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/src/time/clock_nanosleep.c b/src/time/clock_nanosleep.c
> index ec87b9e..9e4d9f1 100644
> --- a/src/time/clock_nanosleep.c
> +++ b/src/time/clock_nanosleep.c
> @@ -1,8 +1,10 @@
> #include <time.h>
> +#include <errno.h>
> #include "syscall.h"
> #include "libc.h"
>
> int clock_nanosleep(clockid_t clk, int flags, const struct timespec *req, struct timespec *rem)
> {
> - return -__syscall_cp(SYS_clock_nanosleep, clk, flags, req, rem);
> + int r = -__syscall_cp(SYS_clock_nanosleep, clk, flags, req, rem);
> + return clk == CLOCK_THREAD_CPUTIME_ID ? EINVAL : r;
> }
See:
On Sat, Sep 17, 2016 at 04:57:09PM +0200, Szabolcs Nagy wrote:
> you elide a cancellation point here.
>
> i think you should check and remap the return value instead.
"Remap the return value" would be more like:
return r==ENOTSUP ? EINVAL : r;
I don't know if it makes a big difference, but in principle it's
better to base conditions on a return value than an argument, since
basing them on an argument requires the value of that argument to be
preserved across the call and can thereby require spilling registers,
etc. I don't think that actually happens on any of the Linux syscall
ABIs but I'm not sure.
Rich
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] fix clock_nanosleep error case
2016-09-18 3:38 ` Rich Felker
@ 2016-09-18 19:01 ` Daniel Sabogal
2016-09-18 19:44 ` Szabolcs Nagy
0 siblings, 1 reply; 5+ messages in thread
From: Daniel Sabogal @ 2016-09-18 19:01 UTC (permalink / raw)
To: Rich Felker; +Cc: musl
On Sat, Sep 17, 2016 at 11:38 PM, Rich Felker <dalias@libc.org> wrote:
> On Sat, Sep 17, 2016 at 12:05:45PM -0400, Daniel Sabogal wrote:
>> posix requires that EINVAL be returned if the first parameter specifies
>> the cpu-time clock of the calling thread (CLOCK_THREAD_CPUTIME_ID).
>> linux returns ENOTSUP instead so we handle this.
>> ---
>> Applied Szabolcs' suggestion for remapping the return value.
>> clock_nanosleep is required to be a cancellation point.
>> ---
>> src/time/clock_nanosleep.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/time/clock_nanosleep.c b/src/time/clock_nanosleep.c
>> index ec87b9e..9e4d9f1 100644
>> --- a/src/time/clock_nanosleep.c
>> +++ b/src/time/clock_nanosleep.c
>> @@ -1,8 +1,10 @@
>> #include <time.h>
>> +#include <errno.h>
>> #include "syscall.h"
>> #include "libc.h"
>>
>> int clock_nanosleep(clockid_t clk, int flags, const struct timespec *req, struct timespec *rem)
>> {
>> - return -__syscall_cp(SYS_clock_nanosleep, clk, flags, req, rem);
>> + int r = -__syscall_cp(SYS_clock_nanosleep, clk, flags, req, rem);
>> + return clk == CLOCK_THREAD_CPUTIME_ID ? EINVAL : r;
>> }
>
> See:
>
> On Sat, Sep 17, 2016 at 04:57:09PM +0200, Szabolcs Nagy wrote:
>> you elide a cancellation point here.
>>
>> i think you should check and remap the return value instead.
>
> "Remap the return value" would be more like:
>
> return r==ENOTSUP ? EINVAL : r;
I wasn't sure about remapping all return values of ENOTSUP to EINVAL.
There are other clocks (extensions) where linux and glibc return ENOTSUP.
I looked through Debian Code Search, but didn't really find anything that
actually uses or depends on such behavior for those extensions.
I suppose this might be fine.
> I don't know if it makes a big difference, but in principle it's
> better to base conditions on a return value than an argument, since
> basing them on an argument requires the value of that argument to be
> preserved across the call and can thereby require spilling registers,
> etc. I don't think that actually happens on any of the Linux syscall
> ABIs but I'm not sure.
OK.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] fix clock_nanosleep error case
2016-09-18 19:01 ` Daniel Sabogal
@ 2016-09-18 19:44 ` Szabolcs Nagy
0 siblings, 0 replies; 5+ messages in thread
From: Szabolcs Nagy @ 2016-09-18 19:44 UTC (permalink / raw)
To: musl; +Cc: Rich Felker
* Daniel Sabogal <dsabogalcc@gmail.com> [2016-09-18 15:01:47 -0400]:
> On Sat, Sep 17, 2016 at 11:38 PM, Rich Felker <dalias@libc.org> wrote:
> > On Sat, Sep 17, 2016 at 12:05:45PM -0400, Daniel Sabogal wrote:
> >> posix requires that EINVAL be returned if the first parameter specifies
> >> the cpu-time clock of the calling thread (CLOCK_THREAD_CPUTIME_ID).
> >> linux returns ENOTSUP instead so we handle this.
> >> ---
> >> Applied Szabolcs' suggestion for remapping the return value.
> >> clock_nanosleep is required to be a cancellation point.
> >> ---
> >> src/time/clock_nanosleep.c | 4 +++-
> >> 1 file changed, 3 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/src/time/clock_nanosleep.c b/src/time/clock_nanosleep.c
> >> index ec87b9e..9e4d9f1 100644
> >> --- a/src/time/clock_nanosleep.c
> >> +++ b/src/time/clock_nanosleep.c
> >> @@ -1,8 +1,10 @@
> >> #include <time.h>
> >> +#include <errno.h>
> >> #include "syscall.h"
> >> #include "libc.h"
> >>
> >> int clock_nanosleep(clockid_t clk, int flags, const struct timespec *req, struct timespec *rem)
> >> {
> >> - return -__syscall_cp(SYS_clock_nanosleep, clk, flags, req, rem);
> >> + int r = -__syscall_cp(SYS_clock_nanosleep, clk, flags, req, rem);
> >> + return clk == CLOCK_THREAD_CPUTIME_ID ? EINVAL : r;
> >> }
> >
> > See:
> >
> > On Sat, Sep 17, 2016 at 04:57:09PM +0200, Szabolcs Nagy wrote:
> >> you elide a cancellation point here.
> >>
> >> i think you should check and remap the return value instead.
> >
> > "Remap the return value" would be more like:
> >
> > return r==ENOTSUP ? EINVAL : r;
>
> I wasn't sure about remapping all return values of ENOTSUP to EINVAL.
> There are other clocks (extensions) where linux and glibc return ENOTSUP.
ah. i assumed ENOTSUP is always wrong, then i guess the patch is ok.
> I looked through Debian Code Search, but didn't really find anything that
> actually uses or depends on such behavior for those extensions.
>
> I suppose this might be fine.
>
> > I don't know if it makes a big difference, but in principle it's
> > better to base conditions on a return value than an argument, since
> > basing them on an argument requires the value of that argument to be
> > preserved across the call and can thereby require spilling registers,
> > etc. I don't think that actually happens on any of the Linux syscall
> > ABIs but I'm not sure.
>
> OK.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] fix clock_nanosleep error case
2016-09-17 16:05 [PATCH v2] fix clock_nanosleep error case Daniel Sabogal
2016-09-18 3:38 ` Rich Felker
@ 2016-10-20 5:47 ` Rich Felker
1 sibling, 0 replies; 5+ messages in thread
From: Rich Felker @ 2016-10-20 5:47 UTC (permalink / raw)
To: musl
On Sat, Sep 17, 2016 at 12:05:45PM -0400, Daniel Sabogal wrote:
> posix requires that EINVAL be returned if the first parameter specifies
> the cpu-time clock of the calling thread (CLOCK_THREAD_CPUTIME_ID).
> linux returns ENOTSUP instead so we handle this.
> ---
> Applied Szabolcs' suggestion for remapping the return value.
> clock_nanosleep is required to be a cancellation point.
> ---
> src/time/clock_nanosleep.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/src/time/clock_nanosleep.c b/src/time/clock_nanosleep.c
> index ec87b9e..9e4d9f1 100644
> --- a/src/time/clock_nanosleep.c
> +++ b/src/time/clock_nanosleep.c
> @@ -1,8 +1,10 @@
> #include <time.h>
> +#include <errno.h>
> #include "syscall.h"
> #include "libc.h"
>
> int clock_nanosleep(clockid_t clk, int flags, const struct timespec *req, struct timespec *rem)
> {
> - return -__syscall_cp(SYS_clock_nanosleep, clk, flags, req, rem);
> + int r = -__syscall_cp(SYS_clock_nanosleep, clk, flags, req, rem);
> + return clk == CLOCK_THREAD_CPUTIME_ID ? EINVAL : r;
> }
> --
> 2.10.0
Thanks, and sorry for the delay following up. Committed.
Rich
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2016-10-20 5:47 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2016-09-17 16:05 [PATCH v2] fix clock_nanosleep error case Daniel Sabogal
2016-09-18 3:38 ` Rich Felker
2016-09-18 19:01 ` Daniel Sabogal
2016-09-18 19:44 ` Szabolcs Nagy
2016-10-20 5:47 ` Rich Felker
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