linux-kernel - [PATCH] um: Stop conflating task_struct::stack with thread

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Message-Id: <ab4a63a107ea6589dac2c9e87324db0e98f50a34.1468880505.git.luto@kernel.org>
Date:	Mon, 18 Jul 2016 15:22:27 -0700
From:	Andy Lutomirski <luto@...nel.org>
To:	x86@...nel.org
Cc:	Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>
Subject: [PATCH] um: Stop conflating task_struct::stack with thread_info

From: Linus Torvalds <torvalds@...ux-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@...l.gmail.com>
Signed-off-by: Andy Lutomirski <luto@...nel.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