git: 7cae020b9c97 - main - Simplify signal handling code in libthr by removing use of SYS_sigreturn

The branch main has been updated by imp:

URL: https://cgit.FreeBSD.org/src/commit/?id=7cae020b9c977c11881363d726b13d1cd2feec5e

commit 7cae020b9c977c11881363d726b13d1cd2feec5e
Author:     Dapeng Gao <dg612@cam.ac.uk>
AuthorDate: 2024-06-03 18:18:13 +0000
Commit:     Warner Losh <imp@FreeBSD.org>
CommitDate: 2024-06-06 21:48:39 +0000

    Simplify signal handling code in libthr by removing use of SYS_sigreturn
    
    The use of SYS_sigreturn is unnecessary here.
    
    If handle_signal is called when a signal is delivered, it can just
    return normally back to sigcode which will call sigreturn anyway.
    
    In case handle_signal is called by check_deferred_signal, using
    setcontext is better than SYS_sigreturn because that is the correct
    system call to pair with the earlier getcontext.
    
    Reviewed by:    imp, kib
    Differential Revision:  https://reviews.freebsd.org/D44893
---
 lib/libthr/thread/thr_sig.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/lib/libthr/thread/thr_sig.c b/lib/libthr/thread/thr_sig.c
index ad291d106001..b953c430158c 100644
--- a/lib/libthr/thread/thr_sig.c
+++ b/lib/libthr/thread/thr_sig.c
@@ -247,7 +247,6 @@ static void
 handle_signal(struct sigaction *actp, int sig, siginfo_t *info, ucontext_t *ucp)
 {
 	struct pthread *curthread = _get_curthread();
-	ucontext_t uc2;
 	__siginfohandler_t *sigfunc;
 	int cancel_point;
 	int cancel_async;
@@ -307,13 +306,11 @@ handle_signal(struct sigaction *actp, int sig, siginfo_t *info, ucontext_t *ucp)
 	curthread->cancel_point = cancel_point;
 	curthread->cancel_enable = cancel_enable;
 
-	memcpy(&uc2, ucp, sizeof(uc2));
-	SIGDELSET(uc2.uc_sigmask, SIGCANCEL);
+	SIGDELSET(ucp->uc_sigmask, SIGCANCEL);
 
 	/* reschedule cancellation */
-	check_cancel(curthread, &uc2);
+	check_cancel(curthread, ucp);
 	errno = err;
-	syscall(SYS_sigreturn, &uc2);
 }
 
 void
@@ -400,6 +397,7 @@ check_deferred_signal(struct pthread *curthread)
 	/* remove signal */
 	curthread->deferred_siginfo.si_signo = 0;
 	handle_signal(&act, info.si_signo, &info, uc);
+	syscall(SYS_sigreturn, uc);
 }
 
 static void