Extend struct sysvec with new method sv_schedtail, which is used for an

explicit process at fork trampoline path instead of eventhadler(schedtail)
invocation for each child process.

Remove eventhandler(schedtail) code and change linux ABI to use newly added
sysvec method.

While here replace explicit comparing of module sysentvec structure with the
newly created process sysentvec to detect the linux ABI.

Discussed with:	kib

MFC after:	2 Week

3 files changed, 4 insertions, 4 deletions

diff --git a/sys/i386/i386/elf_machdep.c b/sys/i386/i386/elf_machdep.c
index df3f48f..a782445 100644
--- a/sys/i386/i386/elf_machdep.c
+++ b/sys/i386/i386/elf_machdep.c
@@ -78,6 +78,7 @@ struct sysentvec elf32_freebsd_sysvec = {
 	.sv_set_syscall_retval = cpu_set_syscall_retval,
 	.sv_fetch_syscall_args = cpu_fetch_syscall_args,
 	.sv_syscallnames = syscallnames,
+	.sv_schedtail	= NULL,
 };
 
 static Elf32_Brandinfo freebsd_brand_info = {
diff --git a/sys/i386/ibcs2/ibcs2_sysvec.c b/sys/i386/ibcs2/ibcs2_sysvec.c
index d69a244..5b6f680 100644
--- a/sys/i386/ibcs2/ibcs2_sysvec.c
+++ b/sys/i386/ibcs2/ibcs2_sysvec.c
@@ -90,6 +90,7 @@ struct sysentvec ibcs2_svr3_sysvec = {
 	.sv_set_syscall_retval = cpu_set_syscall_retval,
 	.sv_fetch_syscall_args = cpu_fetch_syscall_args,
 	.sv_syscallnames = NULL,
+	.sv_schedtail	= NULL,
 };
 
 static int
diff --git a/sys/i386/linux/linux_sysvec.c b/sys/i386/linux/linux_sysvec.c
index c0d9c23..62901d4 100644
--- a/sys/i386/linux/linux_sysvec.c
+++ b/sys/i386/linux/linux_sysvec.c
@@ -112,7 +112,6 @@ static int linux_szplatform;
 const char *linux_platform;
 
 static eventhandler_tag linux_exit_tag;
-static eventhandler_tag linux_schedtail_tag;
 static eventhandler_tag linux_exec_tag;
 
 /*
@@ -998,6 +997,7 @@ struct sysentvec linux_sysvec = {
 	.sv_set_syscall_retval = cpu_set_syscall_retval,
 	.sv_fetch_syscall_args = linux_fetch_syscall_args,
 	.sv_syscallnames = NULL,
+	.sv_schedtail	= linux_schedtail,
 };
 
 struct sysentvec elf_linux_sysvec = {
@@ -1032,6 +1032,7 @@ struct sysentvec elf_linux_sysvec = {
 	.sv_set_syscall_retval = cpu_set_syscall_retval,
 	.sv_fetch_syscall_args = linux_fetch_syscall_args,
 	.sv_syscallnames = NULL,
+	.sv_schedtail	= linux_schedtail,
 };
 
 static char GNU_ABI_VENDOR[] = "GNU";
@@ -1125,8 +1126,6 @@ linux_elf_modevent(module_t mod, int type, void *data)
 			mtx_init(&futex_mtx, "ftllk", NULL, MTX_DEF);
 			linux_exit_tag = EVENTHANDLER_REGISTER(process_exit, linux_proc_exit,
 			      NULL, 1000);
-			linux_schedtail_tag = EVENTHANDLER_REGISTER(schedtail, linux_schedtail,
-			      NULL, 1000);
 			linux_exec_tag = EVENTHANDLER_REGISTER(process_exec, linux_proc_exec,
 			      NULL, 1000);
 			linux_get_machine(&linux_platform);
@@ -1159,7 +1158,6 @@ linux_elf_modevent(module_t mod, int type, void *data)
 			sx_destroy(&emul_shared_lock);
 			mtx_destroy(&futex_mtx);
 			EVENTHANDLER_DEREGISTER(process_exit, linux_exit_tag);
-			EVENTHANDLER_DEREGISTER(schedtail, linux_schedtail_tag);
 			EVENTHANDLER_DEREGISTER(process_exec, linux_exec_tag);
 			linux_osd_jail_deregister();
 			if (bootverbose)