From ba31c1a48538992316cc71ce94fa9cd3e7b427c0 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 6 Nov 2019 22:55:36 +0100 Subject: futex: Move futex exit handling into futex code 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 Reviewed-by: Ingo Molnar Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20191106224556.049705556@linutronix.de --- kernel/fork.c | 25 +++---------------------- 1 file changed, 3 insertions(+), 22 deletions(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index bcdf53125210..bd7c218691d4 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1286,20 +1286,7 @@ static int wait_for_vfork_done(struct task_struct *child, 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); @@ -2062,14 +2049,8 @@ static __latent_entropy 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 */ -- cgit v1.2.3 From 4610ba7ad877fafc0a25a30c6c82015304120426 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 6 Nov 2019 22:55:38 +0100 Subject: exit/exec: Seperate mm_release() mm_release() contains the futex exit handling. mm_release() is called from do_exit()->exit_mm() and from exec()->exec_mm(). In the exit_mm() case PF_EXITING and the futex state is updated. In the exec_mm() case these states are not touched. As the futex exit code needs further protections against exit races, this needs to be split into two functions. Preparatory only, no functional change. Signed-off-by: Thomas Gleixner Reviewed-by: Ingo Molnar Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20191106224556.240518241@linutronix.de --- fs/exec.c | 2 +- include/linux/sched/mm.h | 6 ++++-- kernel/exit.c | 2 +- kernel/fork.c | 12 +++++++++++- 4 files changed, 17 insertions(+), 5 deletions(-) (limited to 'kernel/fork.c') diff --git a/fs/exec.c b/fs/exec.c index 555e93c7dec8..c27231234764 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1015,7 +1015,7 @@ static int exec_mmap(struct mm_struct *mm) /* Notify parent that we're no longer interested in the old VM */ tsk = current; old_mm = current->mm; - mm_release(tsk, old_mm); + exec_mm_release(tsk, old_mm); if (old_mm) { sync_mm_rss(old_mm); diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index e6770012db18..c49257a3b510 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -117,8 +117,10 @@ extern struct mm_struct *get_task_mm(struct task_struct *task); * succeeds. */ extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode); -/* Remove the current tasks stale references to the old mm_struct */ -extern void mm_release(struct task_struct *, struct mm_struct *); +/* Remove the current tasks stale references to the old mm_struct on exit() */ +extern void exit_mm_release(struct task_struct *, struct mm_struct *); +/* Remove the current tasks stale references to the old mm_struct on exec() */ +extern void exec_mm_release(struct task_struct *, struct mm_struct *); #ifdef CONFIG_MEMCG extern void mm_update_next_owner(struct mm_struct *mm); diff --git a/kernel/exit.c b/kernel/exit.c index d11bdcaac2e1..cd893b530902 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -437,7 +437,7 @@ static void exit_mm(void) struct mm_struct *mm = current->mm; struct core_state *core_state; - mm_release(current, mm); + exit_mm_release(current, mm); if (!mm) return; sync_mm_rss(mm); diff --git a/kernel/fork.c b/kernel/fork.c index bd7c218691d4..096f9d840bb8 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1283,7 +1283,7 @@ static int wait_for_vfork_done(struct task_struct *child, * restoring the old one. . . * Eric Biederman 10 January 1998 */ -void mm_release(struct task_struct *tsk, struct mm_struct *mm) +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); @@ -1320,6 +1320,16 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm) complete_vfork_done(tsk); } +void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm) +{ + mm_release(tsk, mm); +} + +void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm) +{ + mm_release(tsk, mm); +} + /** * dup_mm() - duplicates an existing mm structure * @tsk: the task_struct with which the new mm will be associated. -- cgit v1.2.3 From 150d71584b12809144b8145b817e83b81158ae5f Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 6 Nov 2019 22:55:39 +0100 Subject: futex: Split futex_mm_release() for exit/exec 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 Reviewed-by: Ingo Molnar Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20191106224556.332094221@linutronix.de --- include/linux/futex.h | 6 ++++-- kernel/fork.c | 5 ++--- kernel/futex.c | 7 ++++++- 3 files changed, 12 insertions(+), 6 deletions(-) (limited to 'kernel/fork.c') diff --git a/include/linux/futex.h b/include/linux/futex.h index 025ad96bcf9d..6414cfaf88e0 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -93,14 +93,16 @@ static inline void futex_exit_done(struct task_struct *tsk) 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) { } static inline long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, u32 __user *uaddr2, u32 val2, u32 val3) diff --git a/kernel/fork.c b/kernel/fork.c index 096f9d840bb8..f1eb4d1f1a3b 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1285,9 +1285,6 @@ static int wait_for_vfork_done(struct task_struct *child, */ 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 */ @@ -1322,11 +1319,13 @@ static void mm_release(struct task_struct *tsk, struct mm_struct *mm) 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); } diff --git a/kernel/futex.c b/kernel/futex.c index 41c75277d7d1..909e4d3c3099 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -3661,7 +3661,7 @@ static void exit_robust_list(struct task_struct *curr) } } -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); @@ -3679,6 +3679,11 @@ void futex_mm_release(struct task_struct *tsk) 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) { -- cgit v1.2.3