[PATCH] um: Stop conflating task_struct::stack with thread_info

[PATCH] um: Stop conflating task_struct::stack with thread_info

[Andy Lutomirski]

From: Linus Torvalds <torvalds@linux-foundation.org>

thread_info may move in the future, so use the accessors.

[Andy Lutomirski wrote this changelog message and changed
 "task_thread_info(child)->cpu" to "task_cpu(child)".]

Message-Id: <CA+55aFxvZhBu9U1cqpVm4frv0p5mqu=0TxsSqE-=95ft8HvCVA@mail.gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/um/ptrace_32.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/um/ptrace_32.c b/arch/x86/um/ptrace_32.c
index ebd4dd6ef73b..2a6f781ce9cf 100644
--- a/arch/x86/um/ptrace_32.c
+++ b/arch/x86/um/ptrace_32.c
@@ -191,7 +191,7 @@ int peek_user(struct task_struct *child, long addr, long data)
 
 static int get_fpregs(struct user_i387_struct __user *buf, struct task_struct *child)
 {
-	int err, n, cpu = ((struct thread_info *) child->stack)->cpu;
+	int err, n, cpu = task_cpu(child);
 	struct user_i387_struct fpregs;
 
 	err = save_i387_registers(userspace_pid[cpu],
@@ -208,7 +208,7 @@ static int get_fpregs(struct user_i387_struct __user *buf, struct task_struct *c
 
 static int set_fpregs(struct user_i387_struct __user *buf, struct task_struct *child)
 {
-	int n, cpu = ((struct thread_info *) child->stack)->cpu;
+	int n, cpu = task_cpu(child);
 	struct user_i387_struct fpregs;
 
 	n = copy_from_user(&fpregs, buf, sizeof(fpregs));
@@ -221,7 +221,7 @@ static int set_fpregs(struct user_i387_struct __user *buf, struct task_struct *c
 
 static int get_fpxregs(struct user_fxsr_struct __user *buf, struct task_struct *child)
 {
-	int err, n, cpu = ((struct thread_info *) child->stack)->cpu;
+	int err, n, cpu = task_cpu(child);
 	struct user_fxsr_struct fpregs;
 
 	err = save_fpx_registers(userspace_pid[cpu], (unsigned long *) &fpregs);
@@ -237,7 +237,7 @@ static int get_fpxregs(struct user_fxsr_struct __user *buf, struct task_struct *
 
 static int set_fpxregs(struct user_fxsr_struct __user *buf, struct task_struct *child)
 {
-	int n, cpu = ((struct thread_info *) child->stack)->cpu;
+	int n, cpu = task_cpu(child);
 	struct user_fxsr_struct fpregs;
 
 	n = copy_from_user(&fpregs, buf, sizeof(fpregs));
-- 
2.7.4

Re: [PATCH] um: Stop conflating task_struct::stack with thread_info

[Andy Lutomirski]

On Mon, Jul 18, 2016 at 3:22 PM, Andy Lutomirski <luto@kernel.org> wrote:
> From: Linus Torvalds <torvalds@linux-foundation.org>
>
> thread_info may move in the future, so use the accessors.
>
> [Andy Lutomirski wrote this changelog message and changed
>  "task_thread_info(child)->cpu" to "task_cpu(child)".]
>
> Message-Id: <CA+55aFxvZhBu9U1cqpVm4frv0p5mqu=0TxsSqE-=95ft8HvCVA@mail.gmail.com>
> Signed-off-by: Andy Lutomirski <luto@kernel.org>

Forgot to cc maintainers...

> ---
>  arch/x86/um/ptrace_32.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/um/ptrace_32.c b/arch/x86/um/ptrace_32.c
> index ebd4dd6ef73b..2a6f781ce9cf 100644
> --- a/arch/x86/um/ptrace_32.c
> +++ b/arch/x86/um/ptrace_32.c
> @@ -191,7 +191,7 @@ int peek_user(struct task_struct *child, long addr, long data)
>
>  static int get_fpregs(struct user_i387_struct __user *buf, struct task_struct *child)
>  {
> -       int err, n, cpu = ((struct thread_info *) child->stack)->cpu;
> +       int err, n, cpu = task_cpu(child);
>         struct user_i387_struct fpregs;
>
>         err = save_i387_registers(userspace_pid[cpu],
> @@ -208,7 +208,7 @@ static int get_fpregs(struct user_i387_struct __user *buf, struct task_struct *c
>
>  static int set_fpregs(struct user_i387_struct __user *buf, struct task_struct *child)
>  {
> -       int n, cpu = ((struct thread_info *) child->stack)->cpu;
> +       int n, cpu = task_cpu(child);
>         struct user_i387_struct fpregs;
>
>         n = copy_from_user(&fpregs, buf, sizeof(fpregs));
> @@ -221,7 +221,7 @@ static int set_fpregs(struct user_i387_struct __user *buf, struct task_struct *c
>
>  static int get_fpxregs(struct user_fxsr_struct __user *buf, struct task_struct *child)
>  {
> -       int err, n, cpu = ((struct thread_info *) child->stack)->cpu;
> +       int err, n, cpu = task_cpu(child);
>         struct user_fxsr_struct fpregs;
>
>         err = save_fpx_registers(userspace_pid[cpu], (unsigned long *) &fpregs);
> @@ -237,7 +237,7 @@ static int get_fpxregs(struct user_fxsr_struct __user *buf, struct task_struct *
>
>  static int set_fpxregs(struct user_fxsr_struct __user *buf, struct task_struct *child)
>  {
> -       int n, cpu = ((struct thread_info *) child->stack)->cpu;
> +       int n, cpu = task_cpu(child);
>         struct user_fxsr_struct fpregs;
>
>         n = copy_from_user(&fpregs, buf, sizeof(fpregs));
> --
> 2.7.4
>



-- 
Andy Lutomirski
AMA Capital Management, LLC