kernel: Allow a kernel thread's name to be set in copy_process

This patch allows kernel users to pass in the thread name so it can be
set during creation instead of having to use set_task_comm after the
thread is created.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 357e006..32c9f01 100644 (file)
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -23,6 +23,7 @@ struct kernel_clone_args {
        int __user *pidfd;
        int __user *child_tid;
        int __user *parent_tid;
+       const char *name;
        int exit_signal;
        unsigned long stack;
        unsigned long stack_size;
@@ -91,7 +92,8 @@ extern void exit_itimers(struct task_struct *);
 extern pid_t kernel_clone(struct kernel_clone_args *kargs);
 struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
 struct task_struct *fork_idle(int);
-extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
+extern pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
+                           unsigned long flags);
 extern pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags);
 extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
 int kernel_wait(pid_t pid, int *stat);

diff --git a/init/main.c b/init/main.c
index 4425d17..49b5e1e 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -707,7 +707,7 @@ noinline void __ref rest_init(void)
        rcu_read_unlock();
 
        numa_default_policy();
-       pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
+       pid = kernel_thread(kthreadd, NULL, NULL, CLONE_FS | CLONE_FILES);
        rcu_read_lock();
        kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
        rcu_read_unlock();

diff --git a/kernel/fork.c b/kernel/fork.c
index f68954d..81dfb25 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2112,6 +2112,9 @@ static __latent_entropy struct task_struct *copy_process(
                siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
        }
 
+       if (args->name)
+               strscpy_pad(p->comm, args->name, sizeof(p->comm));
+
        p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
        /*
         * Clear TID on mm_release()?
@@ -2730,7 +2733,8 @@ pid_t kernel_clone(struct kernel_clone_args *args)
 /*
  * Create a kernel thread.
  */
-pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
+pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
+                   unsigned long flags)
 {
        struct kernel_clone_args args = {
                .flags          = ((lower_32_bits(flags) | CLONE_VM |
@@ -2738,6 +2742,7 @@ pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
                .exit_signal    = (lower_32_bits(flags) & CSIGNAL),
                .fn             = fn,
                .fn_arg         = arg,
+               .name           = name,
                .kthread        = 1,
        };
 

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 7e6751b..fa4a12d 100644 (file)
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -396,7 +396,8 @@ static void create_kthread(struct kthread_create_info *create)
        current->pref_node_fork = create->node;
 #endif
        /* We want our own signal handler (we take no signals by default). */
-       pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
+       pid = kernel_thread(kthread, create, NULL,
+                           CLONE_FS | CLONE_FILES | SIGCHLD);
        if (pid < 0) {
                /* Release the structure when caller killed by a fatal signal. */
                struct completion *done = xchg(&create->done, NULL);