From 38cc11daa43b11b12a7774405accee1007de1adf Mon Sep 17 00:00:00 2001
From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Wed, 16 Jan 2019 16:22:29 +0000
Subject: nptl: Remove pthread_clock_gettime pthread_clock_settime

This patch removes CLOCK_THREAD_CPUTIME_ID and CLOCK_PROCESS_CPUTIME_ID support
from clock_gettime and clock_settime generic implementation.  For Linux, kernel
already provides supports through the syscall and Hurd HTL lacks
__pthread_clock_gettime and __pthread_clock_settime internal implementation.

As described in clock_gettime man-page [1] on 'Historical note for SMP
system', implementing CLOCK_{THREAD,PROCESS}_CPUTIME_ID with timer registers
is error-prone and susceptible to timing and accurary issues that the libc
can not deal without kernel support.

This allows removes unused code which, however, still incur in some runtime
overhead in thread creation (the struct pthread cpuclock_offset
initialization).

If hurd eventually wants to support them it should either either implement as
a kernel facility (or something related due its architecture) or in system
specific implementation.

Checked on aarch64-linux-gnu, x86_64-linux-gnu, and i686-linux-gnu. I also
checked on a i686-gnu build.

	* nptl/Makefile (libpthread-routines): Remove pthread_clock_gettime and
	pthread_clock_settime.
	* nptl/pthreadP.h (__find_thread_by_id): Remove prototype.
	* elf/dl-support.c [!HP_TIMING_NOAVAIL] (_dl_cpuclock_offset): Remove.
	(_dl_non_dynamic_init): Remove _dl_cpuclock_offset setting.
	* elf/rtld.c (_dl_start_final): Likewise.
	* nptl/allocatestack.c (__find_thread_by_id): Remove function.
	* sysdeps/generic/ldsodefs.h [!HP_TIMING_NOAVAIL] (_dl_cpuclock_offset):
	Remove.
	* sysdeps/mach/hurd/dl-sysdep.c [!HP_TIMING_NOAVAIL]
	(_dl_cpuclock_offset): Remove.
	* nptl/descr.h (struct pthread): Rename cpuclock_offset to
	cpuclock_offset_ununsed.
	* nptl/nptl-init.c (__pthread_initialize_minimal_internal): Remove
	cpuclock_offset set.
	* nptl/pthread_create.c (START_THREAD_DEFN): Likewise.
	* sysdeps/nptl/fork.c (__libc_fork): Likewise.
	* nptl/pthread_clock_gettime.c: Remove file.
	* nptl/pthread_clock_settime.c: Likewise.
	* sysdeps/unix/clock_gettime.c (hp_timing_gettime): Remove function.
	[HP_TIMING_AVAIL] (realtime_gettime): Remove CLOCK_THREAD_CPUTIME_ID
	and CLOCK_PROCESS_CPUTIME_ID support.
	* sysdeps/unix/clock_settime.c (hp_timing_gettime): Likewise.
	[HP_TIMING_AVAIL] (realtime_gettime): Likewise.
	* sysdeps/posix/clock_getres.c (hp_timing_getres): Likewise.
	[HP_TIMING_AVAIL] (__clock_getres): Likewise.
	* sysdeps/unix/clock_nanosleep.c (CPUCLOCK_P, INVALID_CLOCK_P):
	Likewise.
	(__clock_nanosleep): Remove CPUCLOCK_P and INVALID_CLOCK_P usage.

[1] http://man7.org/linux/man-pages/man2/clock_gettime.2.html
---
 nptl/allocatestack.c | 48 ------------------------------------------------
 1 file changed, 48 deletions(-)

(limited to 'nptl/allocatestack.c')

diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
index d8e8570a7d..fcbc46f0d7 100644
--- a/nptl/allocatestack.c
+++ b/nptl/allocatestack.c
@@ -963,54 +963,6 @@ __reclaim_stacks (void)
 }
 
 
-#if HP_TIMING_AVAIL
-# undef __find_thread_by_id
-/* Find a thread given the thread ID.  */
-attribute_hidden
-struct pthread *
-__find_thread_by_id (pid_t tid)
-{
-  struct pthread *result = NULL;
-
-  lll_lock (stack_cache_lock, LLL_PRIVATE);
-
-  /* Iterate over the list with system-allocated threads first.  */
-  list_t *runp;
-  list_for_each (runp, &stack_used)
-    {
-      struct pthread *curp;
-
-      curp = list_entry (runp, struct pthread, list);
-
-      if (curp->tid == tid)
-	{
-	  result = curp;
-	  goto out;
-	}
-    }
-
-  /* Now the list with threads using user-allocated stacks.  */
-  list_for_each (runp, &__stack_user)
-    {
-      struct pthread *curp;
-
-      curp = list_entry (runp, struct pthread, list);
-
-      if (curp->tid == tid)
-	{
-	  result = curp;
-	  goto out;
-	}
-    }
-
- out:
-  lll_unlock (stack_cache_lock, LLL_PRIVATE);
-
-  return result;
-}
-#endif
-
-
 #ifdef SIGSETXID
 static void
 setxid_mark_thread (struct xid_command *cmdp, struct pthread *t)
-- 
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