Hi, Waldemar.
Should uClibc-ng support Linux kernels before 2.6.24?
On Thu, Apr 27, 2017 at 8:33 AM, Waldemar Brodkorb <w...@uclibc-ng.org>
wrote:
> Hi Sergey,
> Sergey Korolev wrote,
>
> > Current uClibc-ng version incorrectly calculates clockid
> > in pthread_getcpuclockid (at least for modern kernels). The simplest test
> > program
> >
> > fails with
> >
> > clock_gettime: Invalid argument
> >
> > Tested on Linux 3.4 / MIPS built with GCC 5.4.0.
>
> Thanks for the test case.
>
> > Other implementations, for example musl, use a simple calculation
> > https://git.musl-libc.org/cgit/musl/tree/src/thread/
> pthread_getcpuclockid.c
> >
> > Looks strange, but the official glibc repository
> > https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=nptl/
> > pthread_getcpuclockid.c;hb=HEAD
> > has the same implementation as in uClibc-ng.
>
> uClibc imported NPTL from GNU libc in 2005. There are still many
> similaraties.
>
> Will you propose a new patch? ( I have read your second mail)
>
> best regards
> Waldemar
>
>
From 50266570943a755e42b96e0158ef85e579d2fcf0 Mon Sep 17 00:00:00 2001
From: Sergey Korolev <s.koro...@ndmsystems.com>
Date: Tue, 25 Apr 2017 02:14:59 +0300
Subject: [PATCH] pthread_getcpuclockid.c: fix clockid calculation
According to newer linux kernel sources (since 2.6.24)
MAKE_THREAD_CPUCLOCK macro-like computations used to get clockid.
---
.../unix/sysv/linux/pthread_getcpuclockid.c | 22 ++++------------------
1 file changed, 4 insertions(+), 18 deletions(-)
diff --git a/libpthread/nptl/sysdeps/unix/sysv/linux/pthread_getcpuclockid.c b/libpthread/nptl/sysdeps/unix/sysv/linux/pthread_getcpuclockid.c
index ca3570f..2fe9115 100644
--- a/libpthread/nptl/sysdeps/unix/sysv/linux/pthread_getcpuclockid.c
+++ b/libpthread/nptl/sysdeps/unix/sysv/linux/pthread_getcpuclockid.c
@@ -20,6 +20,8 @@
#include <sys/time.h>
#include <tls.h>
+#define CPUCLOCK_PERTHREAD_MASK 4
+#define CPUCLOCK_SCHED 2
int
pthread_getcpuclockid (
@@ -33,24 +35,8 @@ pthread_getcpuclockid (
/* Not a valid thread handle. */
return ESRCH;
-#ifdef CLOCK_THREAD_CPUTIME_ID
- /* We need to store the thread ID in the CLOCKID variable together
- with a number identifying the clock. We reserve the low 3 bits
- for the clock ID and the rest for the thread ID. This is
- problematic if the thread ID is too large. But 29 bits should be
- fine.
-
- If some day more clock IDs are needed the ID part can be
- enlarged. The IDs are entirely internal. */
- if (pd->tid >= 1 << (8 * sizeof (*clockid) - CLOCK_IDFIELD_SIZE))
- return ERANGE;
-
- /* Store the number. */
- *clockid = CLOCK_THREAD_CPUTIME_ID | (pd->tid << CLOCK_IDFIELD_SIZE);
+ *clockid = ((~(clockid_t) (pd->tid)) << CLOCK_IDFIELD_SIZE)
+ | CPUCLOCK_SCHED | CPUCLOCK_PERTHREAD_MASK;
return 0;
-#else
- /* We don't have a timer for that. */
- return ENOENT;
-#endif
}
--
2.7.4
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