Messages in this thread | | | Date | Wed, 4 Mar 2015 15:07:45 -0800 (PST) | From | David Rientjes <> | Subject | Re: [PATCH] do_fork(): Rename 'stack_size' argument to reflect actual use |
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On Wed, 4 Mar 2015, Alex Dowad wrote:
> The 'stack_size' argument is never used to pass a stack size. It's only used when > forking a kernel thread, in which case it is an argument which should be passed > to the 'main' function which the kernel thread executes. Hence, rename it to > 'kthread_arg'. > > Signed-off-by: Alex Dowad <alexinbeijing@gmail.com> > --- > > Hi, > > Please have a look at this patch. If this is accepted, I have a series of patches > ready for a similar cleanup to all the arch-specific implementations of copy_thread() > (as suggested by Andrew Morton in a private e-mail). > > Thank you, > Alex Dowad > > kernel/fork.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/kernel/fork.c b/kernel/fork.c > index cf65139..b38a2ae 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -1186,10 +1186,12 @@ init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid) > * It copies the registers, and all the appropriate > * parts of the process environment (as per the clone > * flags). The actual kick-off is left to the caller. > + * > + * When copying a kernel thread, 'stack_start' is the function to run. > */ > static struct task_struct *copy_process(unsigned long clone_flags, > unsigned long stack_start, > - unsigned long stack_size, > + unsigned long kthread_arg, > int __user *child_tidptr, > struct pid *pid, > int trace) > @@ -1401,7 +1403,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, > retval = copy_io(clone_flags, p); > if (retval) > goto bad_fork_cleanup_namespaces; > - retval = copy_thread(clone_flags, stack_start, stack_size, p); > + retval = copy_thread(clone_flags, stack_start, kthread_arg, p); > if (retval) > goto bad_fork_cleanup_io; > > @@ -1629,8 +1631,8 @@ struct task_struct *fork_idle(int cpu) > * it and waits for it to finish using the VM if required. > */ > long do_fork(unsigned long clone_flags, > - unsigned long stack_start, > - unsigned long stack_size, > + unsigned long stack_start, /* or function for kthread to run */ > + unsigned long kthread_arg, > int __user *parent_tidptr, > int __user *child_tidptr) > {
Looks fine, but I'm not sure about commenting functional formals. Since copy_process() and do_fork() can have formals with different meanings, then why not just rename them "arg1" and "arg2" respectively and then define in the comment above the function what the possible combinations are?
> @@ -1656,7 +1658,7 @@ long do_fork(unsigned long clone_flags, > trace = 0; > } > > - p = copy_process(clone_flags, stack_start, stack_size, > + p = copy_process(clone_flags, stack_start, kthread_arg, > child_tidptr, NULL, trace); > /* > * Do this prior waking up the new thread - the thread pointer > @@ -1740,7 +1742,7 @@ SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags, > int, tls_val) > #elif defined(CONFIG_CLONE_BACKWARDS3) > SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp, > - int, stack_size, > + int, ignored, > int __user *, parent_tidptr, > int __user *, child_tidptr, > int, tls_val)
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