[PATCH 01/11] fork: introduce kernel_clone()

Christian Brauner
2020-08-18T17:34:50Z

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@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.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