Patchwork Define GEN_AS_CONST_HEADERS when generating header files [BZ #22792]

login
register
mail settings
Submitter H.J. Lu
Date Feb. 8, 2018, 5:58 p.m.
Message ID <20180208175818.GA8519@gmail.com>
Download mbox | patch
Permalink /patch/25874/
State New
Headers show

Comments

H.J. Lu - Feb. 8, 2018, 5:58 p.m.
Glibc build generates header files to define constants from special .sym
files.  If a .sym file includes the same header file which it generates,
it leads to circular dependency.  Define GEN_AS_CONST_HEADERS when
generating header files to avoid circular dependency.

<tcb-offsets.h> is needed for i686 and it isn't needed for x86-64 at
least since glibc 2.23.

Tested on i686 and x86-64.

OK for trunk?

H.J.
---
	[BZ #22792]
	* Makerules ($(common-objpfx)%.h): Pass -DGEN_AS_CONST_HEADERS
	to $(CC).
	* sysdeps/unix/sysv/linux/i386/lowlevellock.h: Include
	<tcb-offsets.h> only if GEN_AS_CONST_HEADERS isn't defined.
	* sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Don't include
	<tcb-offsets.h>.
---
 Makerules                                     | 4 +++-
 sysdeps/unix/sysv/linux/i386/lowlevellock.h   | 4 +++-
 sysdeps/unix/sysv/linux/x86_64/lowlevellock.h | 1 -
 3 files changed, 6 insertions(+), 3 deletions(-)
Florian Weimer - Feb. 21, 2018, 7:09 a.m.
On 02/08/2018 06:58 PM, H.J. Lu wrote:
> 	[BZ #22792]
> 	* Makerules ($(common-objpfx)%.h): Pass -DGEN_AS_CONST_HEADERS
> 	to $(CC).
> 	* sysdeps/unix/sysv/linux/i386/lowlevellock.h: Include
> 	<tcb-offsets.h> only if GEN_AS_CONST_HEADERS isn't defined.
> 	* sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Don't include
> 	<tcb-offsets.h>.

It looks to me that a cleaner fix would be to move the definition of the 
TCB types to a separate header.

The circular dependency is just a cosmetic warning from make, right?

Thanks,
Florian
H.J. Lu - Feb. 21, 2018, 3:40 p.m.
On Tue, Feb 20, 2018 at 11:09 PM, Florian Weimer <fweimer@redhat.com> wrote:
> On 02/08/2018 06:58 PM, H.J. Lu wrote:
>>
>>         [BZ #22792]
>>         * Makerules ($(common-objpfx)%.h): Pass -DGEN_AS_CONST_HEADERS
>>         to $(CC).
>>         * sysdeps/unix/sysv/linux/i386/lowlevellock.h: Include
>>         <tcb-offsets.h> only if GEN_AS_CONST_HEADERS isn't defined.
>>         * sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Don't include
>>         <tcb-offsets.h>.
>
>
> It looks to me that a cleaner fix would be to move the definition of the TCB
> types to a separate header.

I will take a look.

> The circular dependency is just a cosmetic warning from make, right?

It depends on how unlucky you are.  In one case on a many-core machine
with make -j60, I had to kill glibc build since it never stopped.
H.J. Lu - Feb. 21, 2018, 5:19 p.m.
On Wed, Feb 21, 2018 at 7:40 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Tue, Feb 20, 2018 at 11:09 PM, Florian Weimer <fweimer@redhat.com> wrote:
>> On 02/08/2018 06:58 PM, H.J. Lu wrote:
>>>
>>>         [BZ #22792]
>>>         * Makerules ($(common-objpfx)%.h): Pass -DGEN_AS_CONST_HEADERS
>>>         to $(CC).
>>>         * sysdeps/unix/sysv/linux/i386/lowlevellock.h: Include
>>>         <tcb-offsets.h> only if GEN_AS_CONST_HEADERS isn't defined.
>>>         * sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Don't include
>>>         <tcb-offsets.h>.
>>
>>
>> It looks to me that a cleaner fix would be to move the definition of the TCB
>> types to a separate header.
>
> I will take a look.

sysdeps/i386/nptl/tcb-offsets.sym has

#include <sysdep.h>
#include <tls.h>
#include <kernel-features.h>

RESULT offsetof (struct pthread, result)
TID offsetof (struct pthread, tid)
CANCELHANDLING offsetof (struct pthread, cancelhandling)
CLEANUP_JMP_BUF offsetof (struct pthread, cleanup_jmp_buf)
MULTIPLE_THREADS_OFFSET offsetof (tcbhead_t, multiple_threads)
SYSINFO_OFFSET offsetof (tcbhead_t, sysinfo)
CLEANUP offsetof (struct pthread, cleanup)
CLEANUP_PREV offsetof (struct _pthread_cleanup_buffer, __prev)
MUTEX_FUTEX offsetof (pthread_mutex_t, __data.__lock)
POINTER_GUARD offsetof (tcbhead_t, pointer_guard)
#ifndef __ASSUME_PRIVATE_FUTEX
PRIVATE_FUTEX offsetof (tcbhead_t, private_futex)
#endif

It covers more than just tcbhead_t.  A separate header file for tcbhead_t
won't help here.

>> The circular dependency is just a cosmetic warning from make, right?
>
> It depends on how unlucky you are.  In one case on a many-core machine
> with make -j60, I had to kill glibc build since it never stopped.
>
>
> --
> H.J.

Patch

diff --git a/Makerules b/Makerules
index ef6abeac6d..10a2e83468 100644
--- a/Makerules
+++ b/Makerules
@@ -276,10 +276,12 @@  ifdef gen-as-const-headers
 # Generating headers for assembly constants.
 # We need this defined early to get into before-compile before
 # it's used in sysd-rules, below.
+# Define GEN_AS_CONST_HEADERS to avoid circular dependency [BZ #22792].
 $(common-objpfx)%.h $(common-objpfx)%.h.d: $(..)scripts/gen-as-const.awk \
 					   %.sym $(common-before-compile)
 	$(AWK) -f $< $(filter %.sym,$^) \
-	| $(CC) -S -o $(@:.h.d=.h)T3 $(CFLAGS) $(CPPFLAGS) -x c - \
+	| $(CC) -S -o $(@:.h.d=.h)T3 $(CFLAGS) $(CPPFLAGS) \
+		-DGEN_AS_CONST_HEADERS -x c - \
 		-MD -MP -MF $(@:.h=.h.d)T -MT '$(@:.h=.h.d) $(@:.h.d=.h)'
 	sed -n 's/^.*@@@name@@@\([^@]*\)@@@value@@@[^0-9Xxa-fA-F-]*\([0-9Xxa-fA-F-][0-9Xxa-fA-F-]*\).*@@@end@@@.*$$/#define \1 \2/p' \
 		$(@:.h.d=.h)T3 > $(@:.h.d=.h)T
diff --git a/sysdeps/unix/sysv/linux/i386/lowlevellock.h b/sysdeps/unix/sysv/linux/i386/lowlevellock.h
index fb59b57934..9f081e8a05 100644
--- a/sysdeps/unix/sysv/linux/i386/lowlevellock.h
+++ b/sysdeps/unix/sysv/linux/i386/lowlevellock.h
@@ -26,7 +26,9 @@ 
 # include <sys/param.h>
 # include <bits/pthreadtypes.h>
 # include <kernel-features.h>
-# include <tcb-offsets.h>
+# ifndef GEN_AS_CONST_HEADERS
+#  include <tcb-offsets.h>
+# endif
 
 # ifndef LOCK_INSTR
 #  ifdef UP
diff --git a/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h b/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h
index a8bcfbe4a3..eedb6fc990 100644
--- a/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h
+++ b/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h
@@ -26,7 +26,6 @@ 
 # include <sys/param.h>
 # include <bits/pthreadtypes.h>
 # include <kernel-features.h>
-# include <tcb-offsets.h>
 
 # ifndef LOCK_INSTR
 #  ifdef UP