From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> commit ba31c1a48538992316cc71ce94fa9cd3e7b427c0 upstream. The futex exit handling is #ifdeffed into mm_release() which is not pretty to begin with. But upcoming changes to address futex exit races need to add more functionality to this exit code. Split it out into a function, move it into futex code and make the various futex exit functions static. Preparatory only and no functional change. Folded build fix from Borislav. Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20191106224556.049705556@xxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/linux/compat.h | 2 -- include/linux/futex.h | 24 +++++++++++++++++------- kernel/fork.c | 25 +++---------------------- kernel/futex.c | 28 ++++++++++++++++++++++++++-- 4 files changed, 46 insertions(+), 33 deletions(-) --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -306,8 +306,6 @@ struct compat_kexec_segment; struct compat_mq_attr; struct compat_msgbuf; -extern void compat_exit_robust_list(struct task_struct *curr); - asmlinkage long compat_sys_set_robust_list(struct compat_robust_list_head __user *head, compat_size_t len); --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -1,6 +1,8 @@ #ifndef _LINUX_FUTEX_H #define _LINUX_FUTEX_H +#include <linux/sched.h> + #include <uapi/linux/futex.h> struct inode; @@ -53,14 +55,22 @@ union futex_key { #define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = 0ULL } } #ifdef CONFIG_FUTEX -extern void exit_robust_list(struct task_struct *curr); -extern void exit_pi_state_list(struct task_struct *curr); -#else -static inline void exit_robust_list(struct task_struct *curr) -{ -} -static inline void exit_pi_state_list(struct task_struct *curr) +static inline void futex_init_task(struct task_struct *tsk) { + tsk->robust_list = NULL; +#ifdef CONFIG_COMPAT + tsk->compat_robust_list = NULL; +#endif + INIT_LIST_HEAD(&tsk->pi_state_list); + tsk->pi_state_cache = NULL; } + +void futex_mm_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) { } #endif #endif --- a/kernel/fork.c +++ b/kernel/fork.c @@ -890,20 +890,7 @@ static int wait_for_vfork_done(struct ta void mm_release(struct task_struct *tsk, struct mm_struct *mm) { /* Get rid of any futexes when releasing the mm */ -#ifdef CONFIG_FUTEX - if (unlikely(tsk->robust_list)) { - exit_robust_list(tsk); - tsk->robust_list = NULL; - } -#ifdef CONFIG_COMPAT - if (unlikely(tsk->compat_robust_list)) { - compat_exit_robust_list(tsk); - tsk->compat_robust_list = NULL; - } -#endif - if (unlikely(!list_empty(&tsk->pi_state_list))) - exit_pi_state_list(tsk); -#endif + futex_mm_release(tsk); uprobe_free_utask(tsk); @@ -1511,14 +1498,8 @@ static struct task_struct *copy_process( #ifdef CONFIG_BLOCK p->plug = NULL; #endif -#ifdef CONFIG_FUTEX - p->robust_list = NULL; -#ifdef CONFIG_COMPAT - p->compat_robust_list = NULL; -#endif - INIT_LIST_HEAD(&p->pi_state_list); - p->pi_state_cache = NULL; -#endif + futex_init_task(p); + /* * sigaltstack should be cleared when sharing the same VM */ --- a/kernel/futex.c +++ b/kernel/futex.c @@ -331,6 +331,12 @@ static inline bool should_fail_futex(boo } #endif /* CONFIG_FAIL_FUTEX */ +#ifdef CONFIG_COMPAT +static void compat_exit_robust_list(struct task_struct *curr); +#else +static inline void compat_exit_robust_list(struct task_struct *curr) { } +#endif + static inline void futex_get_mm(union futex_key *key) { atomic_inc(&key->private.mm->mm_count); @@ -889,7 +895,7 @@ static struct task_struct * futex_find_g * Kernel cleans up PI-state, but userspace is likely hosed. * (Robust-futex cleanup is separate and might save the day for userspace.) */ -void exit_pi_state_list(struct task_struct *curr) +static void exit_pi_state_list(struct task_struct *curr) { struct list_head *next, *head = &curr->pi_state_list; struct futex_pi_state *pi_state; @@ -3166,7 +3172,7 @@ static inline int fetch_robust_entry(str * * We silently return on any sign of list-walking problem. */ -void exit_robust_list(struct task_struct *curr) +static void exit_robust_list(struct task_struct *curr) { struct robust_list_head __user *head = curr->robust_list; struct robust_list __user *entry, *next_entry, *pending; @@ -3229,6 +3235,24 @@ void exit_robust_list(struct task_struct curr, pip); } +void futex_mm_release(struct task_struct *tsk) +{ + if (unlikely(tsk->robust_list)) { + exit_robust_list(tsk); + tsk->robust_list = NULL; + } + +#ifdef CONFIG_COMPAT + if (unlikely(tsk->compat_robust_list)) { + compat_exit_robust_list(tsk); + tsk->compat_robust_list = NULL; + } +#endif + + if (unlikely(!list_empty(&tsk->pi_state_list))) + exit_pi_state_list(tsk); +} + long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, u32 __user *uaddr2, u32 val2, u32 val3) {
