NetBSD Problem Report #59134

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Date: Wed,  5 Mar 2025 16:24:41 +0000 (UTC)
From: campbell+netbsd@mumble.net
Reply-To: campbell+netbsd@mumble.net
To: gnats-bugs@NetBSD.org
Subject: POSIX-1.2024: pthread_setcancelstate must be async-signal-safe
X-Send-Pr-Version: www-1.0

>Number:         59134
>Category:       lib
>Synopsis:       POSIX-1.2024: pthread_setcancelstate must be async-signal-safe
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    riastradh
>State:          needs-pullups
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Mar 05 16:25:00 +0000 2025
>Closed-Date:    
>Last-Modified:  Fri Apr 04 20:45:01 +0000 2025
>Originator:     Taylor R Campbell
>Release:        current, 10, 9, ...
>Organization:
The PthreadBSD Signalcancellation
>Environment:
>Description:
Under POSIX.1-2024, pthread_setcancelstate is required to be async-signal-safe: https://pubs.opengroup.org/onlinepubs/9799919799.2024edition/functions/pthread_setcanceltype.html

However, ours is not: it takes pt_lock, which is an ordinary mutex, and so it can't be async-signal-safe.
>How-To-Repeat:
try to use pthread_setcancelstate from a signal handler
>Fix:
Yes, please!

>Release-Note:

>Audit-Trail:
From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/59134 CVS commit: src
Date: Mon, 31 Mar 2025 13:57:07 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Mon Mar 31 13:57:06 UTC 2025

 Modified Files:
 	src/distrib/sets/lists/debug: mi
 	src/distrib/sets/lists/tests: mi
 	src/tests/lib/libpthread: Makefile
 Added Files:
 	src/tests/lib/libpthread: t_cancellation.c

 Log Message:
 pthread_cancel(3): Add some automatic tests.

 PR lib/59240: POSIX.1-2024: cancellation point audit
 PR lib/59134: POSIX-1.2024: pthread_setcancelstate must be
 async-signal-safe


 To generate a diff of this commit:
 cvs rdiff -u -r1.470 -r1.471 src/distrib/sets/lists/debug/mi
 cvs rdiff -u -r1.1362 -r1.1363 src/distrib/sets/lists/tests/mi
 cvs rdiff -u -r1.16 -r1.17 src/tests/lib/libpthread/Makefile
 cvs rdiff -u -r0 -r1.1 src/tests/lib/libpthread/t_cancellation.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/59134 CVS commit: src
Date: Mon, 31 Mar 2025 14:07:10 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Mon Mar 31 14:07:10 UTC 2025

 Modified Files:
 	src/lib/libpthread: pthread.c pthread_cancelstub.c pthread_cond.c
 	    pthread_int.h
 	src/tests/lib/libpthread: t_cancellation.c

 Log Message:
 pthread_cancel(3): Rework.

 Make pthread_setcancelstate(3) async-signal-safe.  (As a side effect,
 this also makes pthread_setcanceltype(3) async-signal-safe, although
 that is not required.)

 PR lib/59134: POSIX-1.2024: pthread_setcancelstate must be
 async-signal-safe


 To generate a diff of this commit:
 cvs rdiff -u -r1.185 -r1.186 src/lib/libpthread/pthread.c
 cvs rdiff -u -r1.45 -r1.46 src/lib/libpthread/pthread_cancelstub.c
 cvs rdiff -u -r1.77 -r1.78 src/lib/libpthread/pthread_cond.c
 cvs rdiff -u -r1.112 -r1.113 src/lib/libpthread/pthread_int.h
 cvs rdiff -u -r1.1 -r1.2 src/tests/lib/libpthread/t_cancellation.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

Responsible-Changed-From-To: lib-bug-people->riastradh
Responsible-Changed-By: riastradh@NetBSD.org
Responsible-Changed-When: Tue, 01 Apr 2025 01:41:33 +0000
Responsible-Changed-Why:
fixed in HEAD, needs pullup-10 and pullup-9 (no API or ABI changes to
libpthread, purely internal changes)


State-Changed-From-To: open->needs-pullups
State-Changed-By: riastradh@NetBSD.org
State-Changed-When: Tue, 01 Apr 2025 01:41:33 +0000
State-Changed-Why:
mine


From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/59134 CVS commit: src/lib/libpthread
Date: Wed, 2 Apr 2025 14:23:34 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Wed Apr  2 14:23:34 UTC 2025

 Modified Files:
 	src/lib/libpthread: pthread.c pthread_int.h

 Log Message:
 pthread_cancel(3): Use _Atomic consistently with C11 atomics.

 Should fix clang build:

 /home/source/ab/HEAD-llvm/src/lib/libpthread/pthread.c:1264:8: error: address argument to atomic operation must be a pointer to _Atomic type ('volatile unsigned int *' invalid)
                     (atomic_load_relaxed(&self->pt_cancel) &
                      ^                   ~~~~~~~~~~~~~~~~
 /home/source/ab/HEAD-llvm/src/lib/libpthread/pthread.c:74:2: note: expanded from macro 'atomic_load_relaxed'
         atomic_load_explicit(p, memory_order_relaxed)
         ^                    ~
 /home/builds/ab/HEAD-llvm/amd64/202504020240Z-dest/usr/include/clang-13.0/stdatomic.h:121:30: note: expanded from macro 'atomic_load_explicit'
 #define atomic_load_explicit __c11_atomic_load

 PR lib/59134: POSIX-1.2024: pthread_setcancelstate must be
 async-signal-safe


 To generate a diff of this commit:
 cvs rdiff -u -r1.186 -r1.187 src/lib/libpthread/pthread.c
 cvs rdiff -u -r1.113 -r1.114 src/lib/libpthread/pthread_int.h

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/59134 CVS commit: src/lib/libpthread
Date: Fri, 4 Apr 2025 20:40:58 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Fri Apr  4 20:40:58 UTC 2025

 Modified Files:
 	src/lib/libpthread: pthread_cancelstub.c

 Log Message:
 libpthread: Use typeof rather than copying signatures of cancelstubs.

 This would have caught my previous mistake with paccept.

 Omit needless declarations that are already covered by the
 compat/*/*.h header files.

 No functional change intended.  This is purely an improvement to
 build-time error detection.

 PR lib/59134: POSIX-1.2024: pthread_setcancelstate must be
 async-signal-safe

 PR lib/59247: pthread_cancelstub.c is inadequately tested


 To generate a diff of this commit:
 cvs rdiff -u -r1.48 -r1.49 src/lib/libpthread/pthread_cancelstub.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

>Unformatted:

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