Merge tag 'kernel-clone-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull kernel_clone() updates from Christian Brauner:
 "During the v5.9 merge window we reworked the process creation
  codepaths across multiple architectures. After this work we were only
  left with the _do_fork() helper based on the struct kernel_clone_args
  calling convention. As was pointed out _do_fork() isn't valid
  kernelese especially for a helper that isn't just static.

  This series removes the _do_fork() helper and introduces the new
  kernel_clone() helper. The process creation cleanup didn't change the
  name to something more reasonable mainly because _do_fork() was used
  in quite a few places. So sending this as a separate series seemed the
  better strategy.

  I originally intended to send this early in the v5.9 development cycle
  after the merge window had closed but given that this was touching
  quite a few places I decided to defer this until the v5.10 merge
  window"

* tag 'kernel-clone-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  sched: remove _do_fork()
  tracing: switch to kernel_clone()
  kgdbts: switch to kernel_clone()
  kprobes: switch to kernel_clone()
  x86: switch to kernel_clone()
  sparc: switch to kernel_clone()
  nios2: switch to kernel_clone()
  m68k: switch to kernel_clone()
  ia64: switch to kernel_clone()
  h8300: switch to kernel_clone()
  fork: introduce kernel_clone()

Author: torvalds

Documentation/trace/histogram.rst

@@ -1495,7 +1495,7 @@ Extended error information
     #
 
     { stacktrace:
-             _do_fork+0x18e/0x330
+             kernel_clone+0x18e/0x330
              kernel_thread+0x29/0x30
              kthreadd+0x154/0x1b0
              ret_from_fork+0x3f/0x70
@@ -1588,7 +1588,7 @@ Extended error information
              SYSC_sendto+0xef/0x170
     } hitcount:         88
     { stacktrace:
-             _do_fork+0x18e/0x330
+             kernel_clone+0x18e/0x330
              SyS_clone+0x19/0x20
              entry_SYSCALL_64_fastpath+0x12/0x6a
     } hitcount:        244

arch/h8300/kernel/process.c

@@ -172,5 +172,5 @@ asmlinkage int sys_clone(unsigned long __user *args)
 	kargs.exit_signal	= (lower_32_bits(clone_flags) & CSIGNAL);
 	kargs.stack		= newsp;
 
-	return _do_fork(&kargs);
+	return kernel_clone(&kargs);
 }

arch/ia64/kernel/process.c

@@ -271,7 +271,7 @@ ia64_load_extra (struct task_struct *task)
  *
  *	<clone syscall>	        <some kernel call frames>
  *	sys_clone		   :
- *	_do_fork		_do_fork
+ *	kernel_clone		kernel_clone
  *	copy_thread		copy_thread
  *
  * This means that the stack layout is as follows:
@@ -411,7 +411,7 @@ asmlinkage long ia64_clone(unsigned long clone_flags, unsigned long stack_start,
 		.tls		= tls,
 	};
 
-	return _do_fork(&args);
+	return kernel_clone(&args);
 }
 
 static void

arch/m68k/kernel/process.c

@@ -107,10 +107,10 @@ void flush_thread(void)
  * on top of pt_regs, which means that sys_clone() arguments would be
  * buried.  We could, of course, copy them, but it's too costly for no
  * good reason - generic clone() would have to copy them *again* for
- * _do_fork() anyway.  So in this case it's actually better to pass pt_regs *
- * and extract arguments for _do_fork() from there.  Eventually we might
- * go for calling _do_fork() directly from the wrapper, but only after we
- * are finished with _do_fork() prototype conversion.
+ * kernel_clone() anyway.  So in this case it's actually better to pass pt_regs *
+ * and extract arguments for kernel_clone() from there.  Eventually we might
+ * go for calling kernel_clone() directly from the wrapper, but only after we
+ * are finished with kernel_clone() prototype conversion.
  */
 asmlinkage int m68k_clone(struct pt_regs *regs)
 {
@@ -125,7 +125,7 @@ asmlinkage int m68k_clone(struct pt_regs *regs)
 		.tls		= regs->d5,
 	};
 
-	return _do_fork(&args);
+	return kernel_clone(&args);
 }
 
 /*

arch/nios2/kernel/process.c

@@ -266,5 +266,5 @@ asmlinkage int nios2_clone(unsigned long clone_flags, unsigned long newsp,
 		.tls		= tls,
 	};
 
-	return _do_fork(&args);
+	return kernel_clone(&args);
 }

arch/sparc/kernel/process.c

@@ -25,7 +25,7 @@ asmlinkage long sparc_fork(struct pt_regs *regs)
 		.stack		= regs->u_regs[UREG_FP],
 	};
 
-	ret = _do_fork(&args);
+	ret = kernel_clone(&args);
 
 	/* If we get an error and potentially restart the system
 	 * call, we're screwed because copy_thread() clobbered
@@ -50,7 +50,7 @@ asmlinkage long sparc_vfork(struct pt_regs *regs)
 		.stack		= regs->u_regs[UREG_FP],
 	};
 
-	ret = _do_fork(&args);
+	ret = kernel_clone(&args);
 
 	/* If we get an error and potentially restart the system
 	 * call, we're screwed because copy_thread() clobbered
@@ -96,7 +96,7 @@ asmlinkage long sparc_clone(struct pt_regs *regs)
 	else
 		args.stack = regs->u_regs[UREG_FP];
 
-	ret = _do_fork(&args);
+	ret = kernel_clone(&args);
 
 	/* If we get an error and potentially restart the system
 	 * call, we're screwed because copy_thread() clobbered

arch/x86/kernel/sys_ia32.c

@@ -251,6 +251,6 @@ COMPAT_SYSCALL_DEFINE5(ia32_clone, unsigned long, clone_flags,
 		.tls		= tls_val,
 	};
 
-	return _do_fork(&args);
+	return kernel_clone(&args);
 }
 #endif /* CONFIG_IA32_EMULATION */

drivers/misc/kgdbts.c

@@ -33,16 +33,16 @@
  * You can also specify optional tests:
  * N## = Go to sleep with interrupts of for ## seconds
  *       to test the HW NMI watchdog
- * F## = Break at do_fork for ## iterations
+ * F## = Break at kernel_clone for ## iterations
  * S## = Break at sys_open for ## iterations
  * I## = Run the single step test ## iterations
  *
- * NOTE: that the do_fork and sys_open tests are mutually exclusive.
+ * NOTE: that the kernel_clone and sys_open tests are mutually exclusive.
  *
  * To invoke the kgdb test suite from boot you use a kernel start
  * argument as follows:
  * 	kgdbts=V1 kgdbwait
- * Or if you wanted to perform the NMI test for 6 seconds and do_fork
+ * Or if you wanted to perform the NMI test for 6 seconds and kernel_clone
  * test for 100 forks, you could use:
  * 	kgdbts=V1N6F100 kgdbwait
  *
@@ -74,7 +74,7 @@
  * echo kgdbts=V1S10000 > /sys/module/kgdbts/parameters/kgdbts
  * fg # and hit control-c
  * fg # and hit control-c
- * ## This tests break points on do_fork
+ * ## This tests break points on kernel_clone
  * while [ 1 ] ; do date > /dev/null ; done &
  * while [ 1 ] ; do date > /dev/null ; done &
  * echo kgdbts=V1F1000 > /sys/module/kgdbts/parameters/kgdbts
@@ -209,8 +209,8 @@ static unsigned long lookup_addr(char *arg)
 		addr = (unsigned long)kgdbts_break_test;
 	else if (!strcmp(arg, "sys_open"))
 		addr = (unsigned long)do_sys_open;
-	else if (!strcmp(arg, "do_fork"))
-		addr = (unsigned long)_do_fork;
+	else if (!strcmp(arg, "kernel_clone"))
+		addr = (unsigned long)kernel_clone;
 	else if (!strcmp(arg, "hw_break_val"))
 		addr = (unsigned long)&hw_break_val;
 	addr = (unsigned long) dereference_function_descriptor((void *)addr);
@@ -310,7 +310,7 @@ static int check_and_rewind_pc(char *put_str, char *arg)
 
 	if (arch_needs_sstep_emulation && sstep_addr &&
 	    ip + offset == sstep_addr &&
-	    ((!strcmp(arg, "sys_open") || !strcmp(arg, "do_fork")))) {
+	    ((!strcmp(arg, "sys_open") || !strcmp(arg, "kernel_clone")))) {
 		/* This is special case for emulated single step */
 		v2printk("Emul: rewind hit single step bp\n");
 		restart_from_top_after_write = 1;
@@ -596,19 +596,19 @@ static struct test_struct singlestep_break_test[] = {
 };
 
 /*
- * Test for hitting a breakpoint at do_fork for what ever the number
+ * Test for hitting a breakpoint at kernel_clone for what ever the number
  * of iterations required by the variable repeat_test.
  */
-static struct test_struct do_fork_test[] = {
+static struct test_struct do_kernel_clone_test[] = {
 	{ "?", "S0*" }, /* Clear break points */
-	{ "do_fork", "OK", sw_break, }, /* set sw breakpoint */
+	{ "kernel_clone", "OK", sw_break, }, /* set sw breakpoint */
 	{ "c", "T0*", NULL, get_thread_id_continue }, /* Continue */
-	{ "do_fork", "OK", sw_rem_break }, /*remove breakpoint */
-	{ "g", "do_fork", NULL, check_and_rewind_pc }, /* check location */
+	{ "kernel_clone", "OK", sw_rem_break }, /*remove breakpoint */
+	{ "g", "kernel_clone", NULL, check_and_rewind_pc }, /* check location */
 	{ "write", "OK", write_regs, emul_reset }, /* Write registers */
 	{ "s", "T0*", emul_sstep_get, emul_sstep_put }, /* Single step */
-	{ "g", "do_fork", NULL, check_single_step },
-	{ "do_fork", "OK", sw_break, }, /* set sw breakpoint */
+	{ "g", "kernel_clone", NULL, check_single_step },
+	{ "kernel_clone", "OK", sw_break, }, /* set sw breakpoint */
 	{ "7", "T0*", skip_back_repeat_test }, /* Loop based on repeat_test */
 	{ "D", "OK", NULL, final_ack_set }, /* detach and unregister I/O */
 	{ "", "", get_cont_catch, put_cont_catch },
@@ -935,11 +935,11 @@ static void run_bad_read_test(void)
 	kgdb_breakpoint();
 }
 
-static void run_do_fork_test(void)
+static void run_kernel_clone_test(void)
 {
 	init_simple_test();
-	ts.tst = do_fork_test;
-	ts.name = "do_fork_test";
+	ts.tst = do_kernel_clone_test;
+	ts.name = "do_kernel_clone_test";
 	/* Activate test with initial breakpoint */
 	kgdb_breakpoint();
 }
@@ -967,7 +967,7 @@ static void run_singlestep_break_test(void)
 static void kgdbts_run_tests(void)
 {
 	char *ptr;
-	int fork_test = 0;
+	int clone_test = 0;
 	int do_sys_open_test = 0;
 	int sstep_test = 1000;
 	int nmi_sleep = 0;
@@ -981,7 +981,7 @@ static void kgdbts_run_tests(void)
 
 	ptr = strchr(config, 'F');
 	if (ptr)
-		fork_test = simple_strtol(ptr + 1, NULL, 10);
+		clone_test = simple_strtol(ptr + 1, NULL, 10);
 	ptr = strchr(config, 'S');
 	if (ptr)
 		do_sys_open_test = simple_strtol(ptr + 1, NULL, 10);
@@ -1025,16 +1025,16 @@ static void kgdbts_run_tests(void)
 		run_nmi_sleep_test(nmi_sleep);
 	}
 
-	/* If the do_fork test is run it will be the last test that is
+	/* If the kernel_clone test is run it will be the last test that is
 	 * executed because a kernel thread will be spawned at the very
 	 * end to unregister the debug hooks.
 	 */
-	if (fork_test) {
-		repeat_test = fork_test;
-		printk(KERN_INFO "kgdbts:RUN do_fork for %i breakpoints\n",
+	if (clone_test) {
+		repeat_test = clone_test;
+		printk(KERN_INFO "kgdbts:RUN kernel_clone for %i breakpoints\n",
 			repeat_test);
 		kthread_run(kgdbts_unreg_thread, NULL, "kgdbts_unreg");
-		run_do_fork_test();
+		run_kernel_clone_test();
 		return;
 	}
 

include/linux/sched/task.h

@@ -83,7 +83,7 @@ extern void do_group_exit(int);
 extern void exit_files(struct task_struct *);
 extern void exit_itimers(struct signal_struct *);
 
-extern long _do_fork(struct kernel_clone_args *kargs);
+extern pid_t kernel_clone(struct kernel_clone_args *kargs);
 struct task_struct *fork_idle(int);
 struct mm_struct *copy_init_mm(void);
 extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);

kernel/fork.c

@@ -2412,14 +2412,14 @@ struct mm_struct *copy_init_mm(void)
  *
  * args->exit_signal is expected to be checked for sanity by the caller.
  */
-long _do_fork(struct kernel_clone_args *args)
+pid_t kernel_clone(struct kernel_clone_args *args)
 {
 	u64 clone_flags = args->flags;
 	struct completion vfork;
 	struct pid *pid;
 	struct task_struct *p;
 	int trace = 0;
-	long nr;
+	pid_t nr;
 
 	/*
 	 * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
@@ -2505,7 +2505,7 @@ pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 		.stack_size	= (unsigned long)arg,
 	};
 
-	return _do_fork(&args);
+	return kernel_clone(&args);
 }
 
 #ifdef __ARCH_WANT_SYS_FORK
@@ -2516,7 +2516,7 @@ SYSCALL_DEFINE0(fork)
 		.exit_signal = SIGCHLD,
 	};
 
-	return _do_fork(&args);
+	return kernel_clone(&args);
 #else
 	/* can not support in nommu mode */
 	return -EINVAL;
@@ -2532,7 +2532,7 @@ SYSCALL_DEFINE0(vfork)
 		.exit_signal	= SIGCHLD,
 	};
 
-	return _do_fork(&args);
+	return kernel_clone(&args);
 }
 #endif
 
@@ -2570,7 +2570,7 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
 		.tls		= tls,
 	};
 
-	return _do_fork(&args);
+	return kernel_clone(&args);
 }
 #endif
 
@@ -2728,7 +2728,7 @@ SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
 	if (!clone3_args_valid(&kargs))
 		return -EINVAL;
 
-	return _do_fork(&kargs);
+	return kernel_clone(&kargs);
 }
 #endif
 
@@ -2891,7 +2891,7 @@ int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
 /*
  * unshare allows a process to 'unshare' part of the process
  * context which was originally shared using clone.  copy_*
- * functions used by _do_fork() cannot be used here directly
+ * functions used by kernel_clone() cannot be used here directly
  * because they modify an inactive task_struct that is being
  * constructed. Here we are modifying the current, active,
  * task_struct.