linux-kernel - [PATCH 01/11] fork: introduce kernel

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Message-Id: <20200818173411.404104-2-christian.brauner@ubuntu.com>
Date:   Tue, 18 Aug 2020 19:34:01 +0200
From:   Christian Brauner <christian.brauner@...ntu.com>
To:     Christoph Hewllig <hch@...radead.org>,
        linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-arch@...r.kernel.org
Cc:     Jonathan Corbet <corbet@....net>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Tony Luck <tony.luck@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Ley Foon Tan <ley.foon.tan@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, Arnd Bergmann <arnd@...db.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        Stafford Horne <shorne@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Kars de Jong <jongk@...ux-m68k.org>,
        Kees Cook <keescook@...omium.org>,
        Greentime Hu <green.hu@...il.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Tom Zanussi <zanussi@...nel.org>,
        Xiao Yang <yangx.jy@...fujitsu.com>, linux-doc@...r.kernel.org,
        uclinux-h8-devel@...ts.sourceforge.jp, linux-ia64@...r.kernel.org,
        linux-m68k@...ts.linux-m68k.org, sparclinux@...r.kernel.org,
        kgdb-bugreport@...ts.sourceforge.net,
        linux-kselftest@...r.kernel.org,
        Christian Brauner <christian.brauner@...ntu.com>,
        Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 01/11] fork: introduce kernel_clone()

The old _do_fork() helper doesn't follow naming conventions of in-kernel
helpers for syscalls. The process creation cleanup in [1] 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.

This commit renames _do_fork() to kernel_clone() but keeps _do_fork() as a
simple static inline wrapper around kernel_clone().
Follow-up patches will switch each caller of _do_fork() and each place where it
is referenced over to kernel_clone(). After all these changes are done, we can
remove _do_fork() completely and will only be left with kernel_clone().

[1]: 9ba27414f2ec ("Merge tag 'fork-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux")
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: "Peter Zijlstra (Intel)" <peterz@...radead.org>
Signed-off-by: Christian Brauner <christian.brauner@...ntu.com>
---
 include/linux/sched/task.h |  6 +++++-
 kernel/fork.c              | 14 +++++++-------
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index a98965007eef..d9ef07359c96 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -83,7 +83,11 @@ 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 int kernel_clone(struct kernel_clone_args *kargs);
+static inline long _do_fork(struct kernel_clone_args *kargs)
+{
+	return kernel_clone(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);
diff --git a/kernel/fork.c b/kernel/fork.c
index 4d32190861bd..34e37cee239f 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2384,7 +2384,7 @@ 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)
+int kernel_clone(struct kernel_clone_args *args)
 {
 	u64 clone_flags = args->flags;
 	struct completion vfork;
@@ -2477,7 +2477,7 @@ 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
@@ -2488,7 +2488,7 @@ SYSCALL_DEFINE0(fork)
 		.exit_signal = SIGCHLD,
 	};
 
-	return _do_fork(&args);
+	return kernel_clone(&args);
 #else
 	/* can not support in nommu mode */
 	return -EINVAL;
@@ -2504,7 +2504,7 @@ SYSCALL_DEFINE0(vfork)
 		.exit_signal	= SIGCHLD,
 	};
 
-	return _do_fork(&args);
+	return kernel_clone(&args);
 }
 #endif
 
@@ -2542,7 +2542,7 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
 		.tls		= tls,
 	};
 
-	return _do_fork(&args);
+	return kernel_clone(&args);
 }
 #endif
 
@@ -2700,7 +2700,7 @@ 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
 
@@ -2863,7 +2863,7 @@ 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.
-- 
2.28.0