Re-backport atomic job locking from 93v- (re: 52067c3, 595a0a5)

McDutchie · McDutchie · commit 1560223d9df5 · 2022-08-01T05:46:37.000+02:00
[This commit was previously reverted because it seemed to cause the build to fail on Cygwin. But I just re-tested it, and it's fine. It may be that my Cygwin installation at the time was defective.] Something similar was previously done in 07cc71b from a Debian patch, and eventually reverted; it redefined the ast atomic functions asoincint() and asodecint() to be gcc-specific. This imports the upstream version from the ksh 93v- beta instead. This commit is based on an OpenSUSE patch: https://build.opensuse.org/package/view_file/shells/ksh/ksh93-joblock.dif src/cmd/ksh93/include/jobs.h: - Replace job locking mechanism with the 93v- version which uses the atomic libast functions asoincint(), asogetint() and asodecint(). See: src/lib/libast/man/aso.3 src/cmd/ksh93/sh/jobs.c: job_subsave(): - Revert gcc optimiser bug workaround from c258a04. It should now be unnecessary.
diff --git a/src/cmd/ksh93/Mamfile b/src/cmd/ksh93/Mamfile
@@ -400,6 +400,9 @@ make install
 					make include/jobs.h implicit
 						prev ${PACKAGE_ast_INCLUDE}/vmalloc.h implicit
 						prev include/terminal.h implicit
+						make ${PACKAGE_ast_INCLUDE}/aso.h implicit
+							prev ${PACKAGE_ast_INCLUDE}/ast_common.h implicit
+						done ${PACKAGE_ast_INCLUDE}/aso.h implicit
 						prev FEATURE/options implicit
 						prev ${PACKAGE_ast_INCLUDE}/sfio.h implicit
 						prev ${PACKAGE_ast_INCLUDE}/ast.h implicit
diff --git a/src/cmd/ksh93/include/jobs.h b/src/cmd/ksh93/include/jobs.h
@@ -30,6 +30,7 @@
 #   include	<signal.h>
 #endif /* !SIGINT */
 #include	"FEATURE/options"
+#include	<aso.h>
 
 #undef JOBS
 #if defined(SIGCLD) && !defined(SIGCHLD)
@@ -120,16 +121,13 @@ extern struct jobs job;
 #define vmbusy()	0
 #endif
 
-#define job_lock()	(job.in_critical++)
+#define job_lock()	asoincint(&job.in_critical)
 #define job_unlock()	\
 	do { \
-		int	sig; \
-		if (!--job.in_critical && (sig = job.savesig)) \
-		{ \
-			if (!job.in_critical++ && !vmbusy()) \
-				job_reap(sig); \
-			job.in_critical--; \
-		} \
+		int	_sig; \
+		if (asogetint(&job.in_critical) == 1 && (_sig = job.savesig) && !vmbusy()) \
+		    job_reap(_sig); \
+		asodecint(&job.in_critical); \
 	} while(0)
 
 extern const char	e_jobusage[];
diff --git a/src/cmd/ksh93/include/version.h b/src/cmd/ksh93/include/version.h
@@ -18,7 +18,7 @@
 
 #define SH_RELEASE_FORK	"93u+m"		/* only change if you develop a new ksh93 fork */
 #define SH_RELEASE_SVER	"1.1.0-alpha"	/* semantic version number: https://semver.org */
-#define SH_RELEASE_DATE	"2022-07-28"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2022-07-31"	/* must be in this format for $((.sh.version)) */
 #define SH_RELEASE_CPYR	"(c) 2020-2022 Contributors to ksh " SH_RELEASE_FORK
 
 /* Scripts sometimes field-split ${.sh.version}, so don't change amount of whitespace. */
diff --git a/src/cmd/ksh93/sh/jobs.c b/src/cmd/ksh93/sh/jobs.c
@@ -1880,14 +1880,8 @@ static int job_chksave(register pid_t pid)
 
 void *job_subsave(void)
 {
-	/*
-	 * We must make a lock first before doing anything else,
-	 * otherwise GCC will remove the job locking mechanism
-	 * as a result of compiler optimization.
-	 */
-	job_lock();
-
 	struct back_save *bp = new_of(struct back_save,0);
+	job_lock();
 	*bp = bck;
 	bp->prev = bck.prev;
 	bck.count = 0;
