releases/4.4.255/futex-split-futex_mm_release-for-exit-exec.patch

From foo@baz Mon Feb  1 04:21:37 PM CET 2021
From: Lee Jones <lee.jones@linaro.org>
Date: Mon,  1 Feb 2021 15:12:07 +0000
Subject: futex: Split futex_mm_release() for exit/exec
To: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Lee Jones <lee.jones@linaro.org>
Message-ID: <20210201151214.2193508-6-lee.jones@linaro.org>

From: Thomas Gleixner <tglx@linutronix.de>

commit 150d71584b12809144b8145b817e83b81158ae5f upstream.

To allow separate handling of the futex exit state in the futex exit code
for exit and exec, split futex_mm_release() into two functions and invoke
them from the corresponding exit/exec_mm_release() callsites.

Preparatory only, no functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191106224556.332094221@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 include/linux/futex.h |    6 ++++--
 kernel/fork.c         |    5 ++---
 kernel/futex.c        |    7 ++++++-
 3 files changed, 12 insertions(+), 6 deletions(-)

--- a/include/linux/futex.h
+++ b/include/linux/futex.h
@@ -98,13 +98,15 @@ static inline void futex_exit_done(struc
 	tsk->futex_state = FUTEX_STATE_DEAD;
 }
 
-void futex_mm_release(struct task_struct *tsk);
+void futex_exit_release(struct task_struct *tsk);
+void futex_exec_release(struct task_struct *tsk);
 
 long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
 	      u32 __user *uaddr2, u32 val2, u32 val3);
 #else
 static inline void futex_init_task(struct task_struct *tsk) { }
-static inline void futex_mm_release(struct task_struct *tsk) { }
 static inline void futex_exit_done(struct task_struct *tsk) { }
+static inline void futex_exit_release(struct task_struct *tsk) { }
+static inline void futex_exec_release(struct task_struct *tsk) { }
 #endif
 #endif
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -889,9 +889,6 @@ static int wait_for_vfork_done(struct ta
  */
 static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
 {
-	/* Get rid of any futexes when releasing the mm */
-	futex_mm_release(tsk);
-
 	uprobe_free_utask(tsk);
 
 	/* Get rid of any cached register state */
@@ -926,11 +923,13 @@ static void mm_release(struct task_struc
 
 void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
 {
+	futex_exit_release(tsk);
 	mm_release(tsk, mm);
 }
 
 void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
 {
+	futex_exec_release(tsk);
 	mm_release(tsk, mm);
 }
 
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3234,7 +3234,7 @@ static void exit_robust_list(struct task
 				   curr, pip);
 }
 
-void futex_mm_release(struct task_struct *tsk)
+void futex_exec_release(struct task_struct *tsk)
 {
 	if (unlikely(tsk->robust_list)) {
 		exit_robust_list(tsk);
@@ -3252,6 +3252,11 @@ void futex_mm_release(struct task_struct
 		exit_pi_state_list(tsk);
 }
 
+void futex_exit_release(struct task_struct *tsk)
+{
+	futex_exec_release(tsk);
+}
+
 long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
 		u32 __user *uaddr2, u32 val2, u32 val3)
 {