Signed-off-by: Alejandro Colomar <[email protected]>
---
man2/futex.2 | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/man2/futex.2 b/man2/futex.2
index f82602c11..837adbd25 100644
--- a/man2/futex.2
+++ b/man2/futex.2
@@ -25,8 +25,8 @@ futex \- fast user-space locking
.SH SYNOPSIS
.nf
.PP
-.B "#include <linux/futex.h>"
-.B "#include <sys/time.h>"
+.B #include <linux/futex.h>
+.B #include <sys/time.h>
.PP
.BI "int futex(int *" uaddr ", int " futex_op ", int " val ,
.BI " const struct timespec *" timeout , \
--
2.28.0
The Linux kernel uses the following:
kernel/futex.c:3778:
SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
u32, val3)
Since there is no glibc wrapper, use the same types the kernel uses.
Signed-off-by: Alejandro Colomar <[email protected]>
---
man2/futex.2 | 27 ++++++++++++++-------------
1 file changed, 14 insertions(+), 13 deletions(-)
diff --git a/man2/futex.2 b/man2/futex.2
index 837adbd25..73de71623 100644
--- a/man2/futex.2
+++ b/man2/futex.2
@@ -26,12 +26,13 @@ futex \- fast user-space locking
.nf
.PP
.B #include <linux/futex.h>
+.B #include <stdint.h>
.B #include <sys/time.h>
.PP
-.BI "int futex(int *" uaddr ", int " futex_op ", int " val ,
+.BI "long futex(uint32_t *" uaddr ", int " futex_op ", uint32_t " val ,
.BI " const struct timespec *" timeout , \
" \fR /* or: \fBuint32_t \fIval2\fP */"
-.BI " int *" uaddr2 ", int " val3 );
+.BI " uint32_t *" uaddr2 ", uint32_t " val3 );
.fi
.PP
.IR Note :
@@ -581,8 +582,8 @@ any of the two supplied futex words:
.IP
.in +4n
.EX
-int oldval = *(int *) uaddr2;
-*(int *) uaddr2 = oldval \fIop\fP \fIoparg\fP;
+uint32_t oldval = *(uint32_t *) uaddr2;
+*(uint32_t *) uaddr2 = oldval \fIop\fP \fIoparg\fP;
futex(uaddr, FUTEX_WAKE, val, 0, 0, 0);
if (oldval \fIcmp\fP \fIcmparg\fP)
futex(uaddr2, FUTEX_WAKE, val2, 0, 0, 0);
@@ -1765,11 +1766,11 @@ Child (18535) 4
#define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); \e
} while (0)
-static int *futex1, *futex2, *iaddr;
+static uint32_t *futex1, *futex2, *iaddr;
static int
-futex(int *uaddr, int futex_op, int val,
- const struct timespec *timeout, int *uaddr2, int val3)
+futex(uint32_t *uaddr, int futex_op, uint32_t val,
+ const struct timespec *timeout, uint32_t *uaddr2, uint32_t val3)
{
return syscall(SYS_futex, uaddr, futex_op, val,
timeout, uaddr2, val3);
@@ -1779,9 +1780,9 @@ futex(int *uaddr, int futex_op, int val,
become 1, and then set the value to 0. */
static void
-fwait(int *futexp)
+fwait(uint32_t *futexp)
{
- int s;
+ long s;
/* atomic_compare_exchange_strong(ptr, oldval, newval)
atomically performs the equivalent of:
@@ -1794,7 +1795,7 @@ fwait(int *futexp)
while (1) {
/* Is the futex available? */
- const int one = 1;
+ const uint32_t one = 1;
if (atomic_compare_exchange_strong(futexp, &one, 0))
break; /* Yes */
@@ -1811,13 +1812,13 @@ fwait(int *futexp)
so that if the peer is blocked in fpost(), it can proceed. */
static void
-fpost(int *futexp)
+fpost(uint32_t *futexp)
{
- int s;
+ long s;
/* atomic_compare_exchange_strong() was described in comments above */
- const int zero = 0;
+ const uint32_t zero = 0;
if (atomic_compare_exchange_strong(futexp, &zero, 1)) {
s = futex(futexp, FUTEX_WAKE, 1, NULL, NULL, 0);
if (s == \-1)
--
2.28.0
BTW, apparently the kernel doesn't use 'const' for 'utime'
('timeout' in the manual page),
but effectively, it doesn't modify it, AFAICS.
Should the kernel use 'const'?
Is there a reason for the kernel not using 'const'?
Should we do anything about it in the manual page?
Thanks,
Alex
On 2020-10-30 13:39, Alejandro Colomar wrote:
> The Linux kernel uses the following:
>
> kernel/futex.c:3778:
> SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
> struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
> u32, val3)
>
> Since there is no glibc wrapper, use the same types the kernel uses.
>
> Signed-off-by: Alejandro Colomar <[email protected]>
> ---
> man2/futex.2 | 27 ++++++++++++++-------------
> 1 file changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/man2/futex.2 b/man2/futex.2
> index 837adbd25..73de71623 100644
> --- a/man2/futex.2
> +++ b/man2/futex.2
> @@ -26,12 +26,13 @@ futex \- fast user-space locking
> .nf
> .PP
> .B #include <linux/futex.h>
> +.B #include <stdint.h>
> .B #include <sys/time.h>
> .PP
> -.BI "int futex(int *" uaddr ", int " futex_op ", int " val ,
> +.BI "long futex(uint32_t *" uaddr ", int " futex_op ", uint32_t " val ,
> .BI " const struct timespec *" timeout , \
> " \fR /* or: \fBuint32_t \fIval2\fP */"
> -.BI " int *" uaddr2 ", int " val3 );
> +.BI " uint32_t *" uaddr2 ", uint32_t " val3 );
> .fi
> .PP
> .IR Note :
> @@ -581,8 +582,8 @@ any of the two supplied futex words:
> .IP
> .in +4n
> .EX
> -int oldval = *(int *) uaddr2;
> -*(int *) uaddr2 = oldval \fIop\fP \fIoparg\fP;
> +uint32_t oldval = *(uint32_t *) uaddr2;
> +*(uint32_t *) uaddr2 = oldval \fIop\fP \fIoparg\fP;
> futex(uaddr, FUTEX_WAKE, val, 0, 0, 0);
> if (oldval \fIcmp\fP \fIcmparg\fP)
> futex(uaddr2, FUTEX_WAKE, val2, 0, 0, 0);
> @@ -1765,11 +1766,11 @@ Child (18535) 4
> #define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); \e
> } while (0)
>
> -static int *futex1, *futex2, *iaddr;
> +static uint32_t *futex1, *futex2, *iaddr;
>
> static int
> -futex(int *uaddr, int futex_op, int val,
> - const struct timespec *timeout, int *uaddr2, int val3)
> +futex(uint32_t *uaddr, int futex_op, uint32_t val,
> + const struct timespec *timeout, uint32_t *uaddr2, uint32_t val3)
> {
> return syscall(SYS_futex, uaddr, futex_op, val,
> timeout, uaddr2, val3);
> @@ -1779,9 +1780,9 @@ futex(int *uaddr, int futex_op, int val,
> become 1, and then set the value to 0. */
>
> static void
> -fwait(int *futexp)
> +fwait(uint32_t *futexp)
> {
> - int s;
> + long s;
>
> /* atomic_compare_exchange_strong(ptr, oldval, newval)
> atomically performs the equivalent of:
> @@ -1794,7 +1795,7 @@ fwait(int *futexp)
> while (1) {
>
> /* Is the futex available? */
> - const int one = 1;
> + const uint32_t one = 1;
> if (atomic_compare_exchange_strong(futexp, &one, 0))
> break; /* Yes */
>
> @@ -1811,13 +1812,13 @@ fwait(int *futexp)
> so that if the peer is blocked in fpost(), it can proceed. */
>
> static void
> -fpost(int *futexp)
> +fpost(uint32_t *futexp)
> {
> - int s;
> + long s;
>
> /* atomic_compare_exchange_strong() was described in comments above */
>
> - const int zero = 0;
> + const uint32_t zero = 0;
> if (atomic_compare_exchange_strong(futexp, &zero, 1)) {
> s = futex(futexp, FUTEX_WAKE, 1, NULL, NULL, 0);
> if (s == \-1)
>
On 10/30/20 1:39 PM, Alejandro Colomar wrote:
> Signed-off-by: Alejandro Colomar <[email protected]>
Hi Alex,
I've applied this patch, but would prefer to avoid such
patches in the future. Nothing is actually broken in the
old version, so I tend to regard such patches as unnecessary
chur,.
Thanks,
Michael
> ---
> man2/futex.2 | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/man2/futex.2 b/man2/futex.2
> index f82602c11..837adbd25 100644
> --- a/man2/futex.2
> +++ b/man2/futex.2
> @@ -25,8 +25,8 @@ futex \- fast user-space locking
> .SH SYNOPSIS
> .nf
> .PP
> -.B "#include <linux/futex.h>"
> -.B "#include <sys/time.h>"
> +.B #include <linux/futex.h>
> +.B #include <sys/time.h>
> .PP
> .BI "int futex(int *" uaddr ", int " futex_op ", int " val ,
> .BI " const struct timespec *" timeout , \
>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
On 10/30/20 1:39 PM, Alejandro Colomar wrote:
> The Linux kernel uses the following:
>
> kernel/futex.c:3778:
> SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
> struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
> u32, val3)
>
> Since there is no glibc wrapper, use the same types the kernel uses.
Thanks. Patch applied.
Cheers,
Michael
> Signed-off-by: Alejandro Colomar <[email protected]>
> ---
> man2/futex.2 | 27 ++++++++++++++-------------
> 1 file changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/man2/futex.2 b/man2/futex.2
> index 837adbd25..73de71623 100644
> --- a/man2/futex.2
> +++ b/man2/futex.2
> @@ -26,12 +26,13 @@ futex \- fast user-space locking
> .nf
> .PP
> .B #include <linux/futex.h>
> +.B #include <stdint.h>
> .B #include <sys/time.h>
> .PP
> -.BI "int futex(int *" uaddr ", int " futex_op ", int " val ,
> +.BI "long futex(uint32_t *" uaddr ", int " futex_op ", uint32_t " val ,
> .BI " const struct timespec *" timeout , \
> " \fR /* or: \fBuint32_t \fIval2\fP */"
> -.BI " int *" uaddr2 ", int " val3 );
> +.BI " uint32_t *" uaddr2 ", uint32_t " val3 );
> .fi
> .PP
> .IR Note :
> @@ -581,8 +582,8 @@ any of the two supplied futex words:
> .IP
> .in +4n
> .EX
> -int oldval = *(int *) uaddr2;
> -*(int *) uaddr2 = oldval \fIop\fP \fIoparg\fP;
> +uint32_t oldval = *(uint32_t *) uaddr2;
> +*(uint32_t *) uaddr2 = oldval \fIop\fP \fIoparg\fP;
> futex(uaddr, FUTEX_WAKE, val, 0, 0, 0);
> if (oldval \fIcmp\fP \fIcmparg\fP)
> futex(uaddr2, FUTEX_WAKE, val2, 0, 0, 0);
> @@ -1765,11 +1766,11 @@ Child (18535) 4
> #define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); \e
> } while (0)
>
> -static int *futex1, *futex2, *iaddr;
> +static uint32_t *futex1, *futex2, *iaddr;
>
> static int
> -futex(int *uaddr, int futex_op, int val,
> - const struct timespec *timeout, int *uaddr2, int val3)
> +futex(uint32_t *uaddr, int futex_op, uint32_t val,
> + const struct timespec *timeout, uint32_t *uaddr2, uint32_t val3)
> {
> return syscall(SYS_futex, uaddr, futex_op, val,
> timeout, uaddr2, val3);
> @@ -1779,9 +1780,9 @@ futex(int *uaddr, int futex_op, int val,
> become 1, and then set the value to 0. */
>
> static void
> -fwait(int *futexp)
> +fwait(uint32_t *futexp)
> {
> - int s;
> + long s;
>
> /* atomic_compare_exchange_strong(ptr, oldval, newval)
> atomically performs the equivalent of:
> @@ -1794,7 +1795,7 @@ fwait(int *futexp)
> while (1) {
>
> /* Is the futex available? */
> - const int one = 1;
> + const uint32_t one = 1;
> if (atomic_compare_exchange_strong(futexp, &one, 0))
> break; /* Yes */
>
> @@ -1811,13 +1812,13 @@ fwait(int *futexp)
> so that if the peer is blocked in fpost(), it can proceed. */
>
> static void
> -fpost(int *futexp)
> +fpost(uint32_t *futexp)
> {
> - int s;
> + long s;
>
> /* atomic_compare_exchange_strong() was described in comments above */
>
> - const int zero = 0;
> + const uint32_t zero = 0;
> if (atomic_compare_exchange_strong(futexp, &zero, 1)) {
> s = futex(futexp, FUTEX_WAKE, 1, NULL, NULL, 0);
> if (s == \-1)
>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
Hi Alex,
On 10/30/20 2:46 PM, Alejandro Colomar wrote:
> BTW, apparently the kernel doesn't use 'const' for 'utime'
> ('timeout' in the manual page),
> but effectively, it doesn't modify it, AFAICS.
>
> Should the kernel use 'const'?
> Is there a reason for the kernel not using 'const'?
> Should we do anything about it in the manual page?
I'm not sure about the kernel, but I think we don't need to
worry in the manual page.
Thanks,
Michael
> On 2020-10-30 13:39, Alejandro Colomar wrote:
>> The Linux kernel uses the following:
>>
>> kernel/futex.c:3778:
>> SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
>> struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
>> u32, val3)
>>
>> Since there is no glibc wrapper, use the same types the kernel uses.
>>
>> Signed-off-by: Alejandro Colomar <[email protected]>
>> ---
>> man2/futex.2 | 27 ++++++++++++++-------------
>> 1 file changed, 14 insertions(+), 13 deletions(-)
>>
>> diff --git a/man2/futex.2 b/man2/futex.2
>> index 837adbd25..73de71623 100644
>> --- a/man2/futex.2
>> +++ b/man2/futex.2
>> @@ -26,12 +26,13 @@ futex \- fast user-space locking
>> .nf
>> .PP
>> .B #include <linux/futex.h>
>> +.B #include <stdint.h>
>> .B #include <sys/time.h>
>> .PP
>> -.BI "int futex(int *" uaddr ", int " futex_op ", int " val ,
>> +.BI "long futex(uint32_t *" uaddr ", int " futex_op ", uint32_t " val ,
>> .BI " const struct timespec *" timeout , \
>> " \fR /* or: \fBuint32_t \fIval2\fP */"
>> -.BI " int *" uaddr2 ", int " val3 );
>> +.BI " uint32_t *" uaddr2 ", uint32_t " val3 );
>> .fi
>> .PP
>> .IR Note :
>> @@ -581,8 +582,8 @@ any of the two supplied futex words:
>> .IP
>> .in +4n
>> .EX
>> -int oldval = *(int *) uaddr2;
>> -*(int *) uaddr2 = oldval \fIop\fP \fIoparg\fP;
>> +uint32_t oldval = *(uint32_t *) uaddr2;
>> +*(uint32_t *) uaddr2 = oldval \fIop\fP \fIoparg\fP;
>> futex(uaddr, FUTEX_WAKE, val, 0, 0, 0);
>> if (oldval \fIcmp\fP \fIcmparg\fP)
>> futex(uaddr2, FUTEX_WAKE, val2, 0, 0, 0);
>> @@ -1765,11 +1766,11 @@ Child (18535) 4
>> #define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); \e
>> } while (0)
>>
>> -static int *futex1, *futex2, *iaddr;
>> +static uint32_t *futex1, *futex2, *iaddr;
>>
>> static int
>> -futex(int *uaddr, int futex_op, int val,
>> - const struct timespec *timeout, int *uaddr2, int val3)
>> +futex(uint32_t *uaddr, int futex_op, uint32_t val,
>> + const struct timespec *timeout, uint32_t *uaddr2, uint32_t val3)
>> {
>> return syscall(SYS_futex, uaddr, futex_op, val,
>> timeout, uaddr2, val3);
>> @@ -1779,9 +1780,9 @@ futex(int *uaddr, int futex_op, int val,
>> become 1, and then set the value to 0. */
>>
>> static void
>> -fwait(int *futexp)
>> +fwait(uint32_t *futexp)
>> {
>> - int s;
>> + long s;
>>
>> /* atomic_compare_exchange_strong(ptr, oldval, newval)
>> atomically performs the equivalent of:
>> @@ -1794,7 +1795,7 @@ fwait(int *futexp)
>> while (1) {
>>
>> /* Is the futex available? */
>> - const int one = 1;
>> + const uint32_t one = 1;
>> if (atomic_compare_exchange_strong(futexp, &one, 0))
>> break; /* Yes */
>>
>> @@ -1811,13 +1812,13 @@ fwait(int *futexp)
>> so that if the peer is blocked in fpost(), it can proceed. */
>>
>> static void
>> -fpost(int *futexp)
>> +fpost(uint32_t *futexp)
>> {
>> - int s;
>> + long s;
>>
>> /* atomic_compare_exchange_strong() was described in comments above */
>>
>> - const int zero = 0;
>> + const uint32_t zero = 0;
>> if (atomic_compare_exchange_strong(futexp, &zero, 1)) {
>> s = futex(futexp, FUTEX_WAKE, 1, NULL, NULL, 0);
>> if (s == \-1)
>>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/