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author | Jens Axboe <axboe@kernel.dk> | 2020-10-26 23:32:28 +0300 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2020-10-29 11:37:36 +0300 |
commit | 12db8b690010ccfadf9d0b49a1e1798e47dbbe1a (patch) | |
tree | 185645b2e040fb94b3dfc06fae3c4f2ea8d734ad /include/linux/tracehook.h | |
parent | 5c251e9dc0e127bac6fc5b8e6696363d2e35f515 (diff) | |
download | linux-12db8b690010ccfadf9d0b49a1e1798e47dbbe1a.tar.xz |
entry: Add support for TIF_NOTIFY_SIGNAL
Add TIF_NOTIFY_SIGNAL handling in the generic entry code, which if set,
will return true if signal_pending() is used in a wait loop. That causes an
exit of the loop so that notify_signal tracehooks can be run. If the wait
loop is currently inside a system call, the system call is restarted once
task_work has been processed.
In preparation for only having arch_do_signal() handle syscall restarts if
_TIF_SIGPENDING isn't set, rename it to arch_do_signal_or_restart(). Pass
in a boolean that tells the architecture specific signal handler if it
should attempt to get a signal, or just process a potential syscall
restart.
For !CONFIG_GENERIC_ENTRY archs, add the TIF_NOTIFY_SIGNAL handling to
get_signal(). This is done to minimize the needed architecture changes to
support this feature.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20201026203230.386348-3-axboe@kernel.dk
Diffstat (limited to 'include/linux/tracehook.h')
-rw-r--r-- | include/linux/tracehook.h | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h index 36fb3bbed6b2..1e8caca92e1f 100644 --- a/include/linux/tracehook.h +++ b/include/linux/tracehook.h @@ -198,4 +198,31 @@ static inline void tracehook_notify_resume(struct pt_regs *regs) blkcg_maybe_throttle_current(); } +/* + * called by exit_to_user_mode_loop() if ti_work & _TIF_NOTIFY_SIGNAL. This + * is currently used by TWA_SIGNAL based task_work, which requires breaking + * wait loops to ensure that task_work is noticed and run. + */ +static inline void tracehook_notify_signal(void) +{ +#if defined(TIF_NOTIFY_SIGNAL) + clear_thread_flag(TIF_NOTIFY_SIGNAL); + smp_mb__after_atomic(); + if (current->task_works) + task_work_run(); +#endif +} + +/* + * Called when we have work to process from exit_to_user_mode_loop() + */ +static inline void set_notify_signal(struct task_struct *task) +{ +#if defined(TIF_NOTIFY_SIGNAL) + if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) && + !wake_up_state(task, TASK_INTERRUPTIBLE)) + kick_process(task); +#endif +} + #endif /* <linux/tracehook.h> */ |