[RFC PATCH v1 29/31] ARC: switch to generic kernel_thread()

[Vineet Gupta]

Signed-off-by: Vineet Gupta <vgu...@synopsys.com>
---
 arch/arc/Kconfig          |    1 +
 arch/arc/kernel/process.c |   29 +++++++++--------------------
 2 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index d6983afa..f3aacfc 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -17,6 +17,7 @@ config ARC
        select GENERIC_FIND_FIRST_BIT
        # for now, we don't need GENERIC_IRQ_PROBE, CONFIG_GENERIC_IRQ_CHIP
        select GENERIC_IRQ_SHOW
+       select GENERIC_KERNEL_THREAD
        select GENERIC_PENDING_IRQ if SMP
        select GENERIC_SMP_IDLE_THREAD
        select HAVE_GENERIC_HARDIRQS
diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c
index fee3e11..d2bb27f 100644
--- a/arch/arc/kernel/process.c
+++ b/arch/arc/kernel/process.c
@@ -142,22 +142,6 @@ void cpu_idle(void)
        }
 }
 
-int kernel_thread(int (*fn) (void *), void *arg, unsigned long flags)
-{
-       struct pt_regs regs = {
-               .r0 = (unsigned long)arg,
-               .r1 = (unsigned long)fn
-       };
-
-       regs.status32 = read_aux_reg(0xa);
-
-       /* Ok, create the new process.. */
-       return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL,
-                      NULL);
-
-}
-EXPORT_SYMBOL(kernel_thread);
-
 asmlinkage void ret_from_fork(void);
 asmlinkage void ret_from_kernel_thread(void) __attribute__((noreturn));
 
@@ -192,7 +176,7 @@ asmlinkage void ret_from_kernel_thread(void) 
__attribute__((noreturn));
  * ------------------  <===== END of PAGE
  */
 int copy_thread(unsigned long clone_flags,
-               unsigned long usp, unsigned long topstk,
+               unsigned long usp, unsigned long arg,
                struct task_struct *p, struct pt_regs *regs)
 {
        struct pt_regs *c_regs;        /* child's pt_regs */
@@ -213,10 +197,12 @@ int copy_thread(unsigned long clone_flags,
         */
        p->thread.ksp = (unsigned long)c_callee;        /* THREAD_KSP */
 
-       /* Copy parents pt regs on child's kernel mode stack */
-       *c_regs = *regs;
+       if (unlikely(p->flags & PF_KTHREAD)) {
+               memset(c_regs, 0, sizeof(struct pt_regs));
+               c_regs->r0 = arg; /* argument to kernel thread */
+               c_regs->r1 = usp;  /* function */
+               c_regs->status32 = read_aux_reg(0xa);
 
-       if (!(user_mode(regs))) {
                c_regs->sp =
                    (unsigned long)task_thread_info(p) + (THREAD_SIZE - 4);
 
@@ -232,6 +218,9 @@ int copy_thread(unsigned long clone_flags,
        childksp[0] = 0;                                /* for POP fp */
        childksp[1] = (unsigned long)ret_from_fork;     /* for POP blink */
 
+       /* Copy parents pt regs on child's kernel mode stack */
+       *c_regs = *regs;
+
        c_regs->sp = usp;
        c_regs->r0 = 0;         /* fork returns 0 in child */
 
-- 
1.7.4.1

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