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* signal: Replace __group_send_sig_info with send_signal_lockedEric W. Biederman2022-05-111-3/+3
| | | | | | | | | | | | The function __group_send_sig_info is just a light wrapper around send_signal_locked with one parameter fixed to a constant value. As the wrapper adds no real value update the code to directly call the wrapped function. Tested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Link: https://lkml.kernel.org/r/20220505182645.497868-2-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* Merge tag 'ptrace-cleanups-for-v5.18' of ↵Linus Torvalds2022-03-281-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull ptrace cleanups from Eric Biederman: "This set of changes removes tracehook.h, moves modification of all of the ptrace fields inside of siglock to remove races, adds a missing permission check to ptrace.c The removal of tracehook.h is quite significant as it has been a major source of confusion in recent years. Much of that confusion was around task_work and TIF_NOTIFY_SIGNAL (which I have now decoupled making the semantics clearer). For people who don't know tracehook.h is a vestiage of an attempt to implement uprobes like functionality that was never fully merged, and was later superseeded by uprobes when uprobes was merged. For many years now we have been removing what tracehook functionaly a little bit at a time. To the point where anything left in tracehook.h was some weird strange thing that was difficult to understand" * tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: ptrace: Remove duplicated include in ptrace.c ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE ptrace: Return the signal to continue with from ptrace_stop ptrace: Move setting/clearing ptrace_message into ptrace_stop tracehook: Remove tracehook.h resume_user_mode: Move to resume_user_mode.h resume_user_mode: Remove #ifdef TIF_NOTIFY_RESUME in set_notify_resume signal: Move set_notify_signal and clear_notify_signal into sched/signal.h task_work: Decouple TIF_NOTIFY_SIGNAL and task_work task_work: Call tracehook_notify_signal from get_signal on all architectures task_work: Introduce task_work_pending task_work: Remove unnecessary include from posix_timers.h ptrace: Remove tracehook_signal_handler ptrace: Remove arch_syscall_{enter,exit}_tracehook ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h ptrace/arm: Rename tracehook_report_syscall report_syscall ptrace: Move ptrace_report_syscall into ptrace.h
| * task_work: Remove unnecessary include from posix_timers.hEric W. Biederman2022-03-101-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Break a header file circular dependency by removing the unnecessary include of task_work.h from posix_timers.h. sched.h -> posix-timers.h posix-timers.h -> task_work.h task_work.h -> sched.h Add missing includes of task_work.h to: arch/x86/mm/tlb.c kernel/time/posix-cpu-timers.c Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/20220309162454.123006-6-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* | prlimit: do not grab the tasklist_lockBarret Rhoden2022-03-081-3/+9
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Unnecessarily grabbing the tasklist_lock can be a scalability bottleneck for workloads that also must grab the tasklist_lock for waiting, killing, and cloning. The tasklist_lock was grabbed to protect tsk->sighand from disappearing (becoming NULL). tsk->signal was already protected by holding a reference to tsk. update_rlimit_cpu() assumed tsk->sighand != NULL. With this commit, it attempts to lock_task_sighand(). However, this means that update_rlimit_cpu() can fail. This only happens when a task is exiting. Note that during exec, sighand may *change*, but it will not be NULL. Prior to this commit, the do_prlimit() ensured that update_rlimit_cpu() would not fail by read locking the tasklist_lock and checking tsk->sighand != NULL. If update_rlimit_cpu() fails, there may be other tasks that are not exiting that share tsk->signal. However, the group_leader is the last task to be released, so if we cannot update_rlimit_cpu(group_leader), then the entire process is exiting. The only other caller of update_rlimit_cpu() is selinux_bprm_committing_creds(). It has tsk == current, so update_rlimit_cpu() cannot fail (current->sighand cannot disappear until current exits). This change resulted in a 14% speedup on a microbenchmark where parents kill and wait on their children, and children getpriority, setpriority, and getrlimit. Signed-off-by: Barret Rhoden <brho@google.com> Link: https://lkml.kernel.org/r/20220106172041.522167-4-brho@google.com Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* posix-cpu-timers: Clear task::posix_cputimers_work in copy_process()Michael Pratt2021-11-021-2/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | copy_process currently copies task_struct.posix_cputimers_work as-is. If a timer interrupt arrives while handling clone and before dup_task_struct completes then the child task will have: 1. posix_cputimers_work.scheduled = true 2. posix_cputimers_work.work queued. copy_process clears task_struct.task_works, so (2) will have no effect and posix_cpu_timers_work will never run (not to mention it doesn't make sense for two tasks to share a common linked list). Since posix_cpu_timers_work never runs, posix_cputimers_work.scheduled is never cleared. Since scheduled is set, future timer interrupts will skip scheduling work, with the ultimate result that the task will never receive timer expirations. Together, the complete flow is: 1. Task 1 calls clone(), enters kernel. 2. Timer interrupt fires, schedules task work on Task 1. 2a. task_struct.posix_cputimers_work.scheduled = true 2b. task_struct.posix_cputimers_work.work added to task_struct.task_works. 3. dup_task_struct() copies Task 1 to Task 2. 4. copy_process() clears task_struct.task_works for Task 2. 5. Future timer interrupts on Task 2 see task_struct.posix_cputimers_work.scheduled = true and skip scheduling work. Fix this by explicitly clearing contents of task_struct.posix_cputimers_work in copy_process(). This was never meant to be shared or inherited across tasks in the first place. Fixes: 1fb497dd0030 ("posix-cpu-timers: Provide mechanisms to defer timer handling to task_work") Reported-by: Rhys Hiltner <rhys@justin.tv> Signed-off-by: Michael Pratt <mpratt@google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20211101210615.716522-1-mpratt@google.com
* posix-cpu-timers: Prevent spuriously armed 0-value itimerFrederic Weisbecker2021-09-231-1/+2
| | | | | | | | | | | | | | | | | Resetting/stopping an itimer eventually leads to it being reprogrammed with an actual "0" value. As a result the itimer expires on the next tick, triggering an unexpected signal. To fix this, make sure that struct signal_struct::it[CPUCLOCK_PROF/VIRT]::expires is set to 0 when setitimer() passes a 0 it_value, indicating that the timer must stop. Fixes: 406dd42bd1ba ("posix-cpu-timers: Force next expiration recalc after itimer reset") Reported-by: Victor Stinner <vstinner@redhat.com> Reported-by: Chris Hixon <linux-kernel-bugs@hixontech.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20210913145332.232023-1-frederic@kernel.org
* posix-cpu-timers: Recalc next expiration when timer_settime() ends up not ↵Frederic Weisbecker2021-08-101-6/+35
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | queueing There are several scenarios that can result in posix_cpu_timer_set() not queueing the timer but still leaving the threadgroup cputime counter running or keeping the tick dependency around for a random amount of time. 1) If timer_settime() is called with a 0 expiration on a timer that is already disabled, the process wide cputime counter will be started and won't ever get a chance to be stopped by stop_process_timer() since no timer is actually armed to be processed. The following snippet is enough to trigger the issue. void trigger_process_counter(void) { timer_t id; struct itimerspec val = { }; timer_create(CLOCK_PROCESS_CPUTIME_ID, NULL, &id); timer_settime(id, TIMER_ABSTIME, &val, NULL); timer_delete(id); } 2) If timer_settime() is called with a 0 expiration on a timer that is already armed, the timer is dequeued but not really disarmed. So the process wide cputime counter and the tick dependency may still remain a while around. The following code snippet keeps this overhead around for one week after the timer deletion: void trigger_process_counter(void) { timer_t id; struct itimerspec val = { }; val.it_value.tv_sec = 604800; timer_create(CLOCK_PROCESS_CPUTIME_ID, NULL, &id); timer_settime(id, 0, &val, NULL); timer_delete(id); } 3) If the timer was initially deactivated, this call to timer_settime() with an early expiration may have started the process wide cputime counter even though the timer hasn't been queued and armed because it has fired early and inline within posix_cpu_timer_set() itself. As a result the process wide cputime counter may never stop until a new timer is ever armed in the future. The following code snippet can reproduce this: void trigger_process_counter(void) { timer_t id; struct itimerspec val = { }; signal(SIGALRM, SIG_IGN); timer_create(CLOCK_PROCESS_CPUTIME_ID, NULL, &id); val.it_value.tv_nsec = 1; timer_settime(id, TIMER_ABSTIME, &val, NULL); } 4) If the timer was initially armed with a former expiration value before this call to timer_settime() and the current call sets an early deadline that has already expired, the timer fires inline within posix_cpu_timer_set(). In this case it must have been dequeued before firing inline with its new expiration value, yet it hasn't been disarmed in this case. So the process wide cputime counter and the tick dependency may still be around for a while even after the timer fired. The following code snippet can reproduce this: void trigger_process_counter(void) { timer_t id; struct itimerspec val = { }; signal(SIGALRM, SIG_IGN); timer_create(CLOCK_PROCESS_CPUTIME_ID, NULL, &id); val.it_value.tv_sec = 100; timer_settime(id, TIMER_ABSTIME, &val, NULL); val.it_value.tv_sec = 0; val.it_value.tv_nsec = 1; timer_settime(id, TIMER_ABSTIME, &val, NULL); } Fix all these issues with triggering the related base next expiration recalculation on the next tick. This also implies to re-evaluate the need to keep around the process wide cputime counter and the tick dependency, in a similar fashion to disarm_timer(). Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210726125513.271824-7-frederic@kernel.org
* posix-cpu-timers: Consolidate timer base accessorFrederic Weisbecker2021-08-101-15/+13
| | | | | | | | | | Remove the ad-hoc timer base accessors and provide a consolidated one. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210726125513.271824-6-frederic@kernel.org
* posix-cpu-timers: Remove confusing return value overrideFrederic Weisbecker2021-08-101-2/+0
| | | | | | | | | | | The end of the function cannot be reached with an error in variable ret. Unconfuse reviewers about that. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210726125513.271824-5-frederic@kernel.org
* posix-cpu-timers: Force next expiration recalc after itimer resetFrederic Weisbecker2021-08-101-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | When an itimer deactivates a previously armed expiration, it simply doesn't do anything. As a result the process wide cputime counter keeps running and the tick dependency stays set until it reaches the old ghost expiration value. This can be reproduced with the following snippet: void trigger_process_counter(void) { struct itimerval n = {}; n.it_value.tv_sec = 100; setitimer(ITIMER_VIRTUAL, &n, NULL); n.it_value.tv_sec = 0; setitimer(ITIMER_VIRTUAL, &n, NULL); } Fix this with resetting the relevant base expiration. This is similar to disarming a timer. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210726125513.271824-4-frederic@kernel.org
* posix-cpu-timers: Force next_expiration recalc after timer deletionFrederic Weisbecker2021-08-101-1/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | A timer deletion only dequeues the timer but it doesn't shutdown the related costly process wide cputimer counter and the tick dependency. The following code snippet keeps this overhead around for one week after the timer deletion: void trigger_process_counter(void) { timer_t id; struct itimerspec val = { }; val.it_value.tv_sec = 604800; timer_create(CLOCK_PROCESS_CPUTIME_ID, NULL, &id); timer_settime(id, 0, &val, NULL); timer_delete(id); } Make sure the next target's tick recalculates the nearest expiration and clears the process wide counter and tick dependency if necessary. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210726125513.271824-3-frederic@kernel.org
* posix-cpu-timers: Assert task sighand is locked while starting cputime counterFrederic Weisbecker2021-08-101-0/+2
| | | | | | | | | | | | | | | | | Starting the process wide cputime counter needs to be done in the same sighand locking sequence than actually arming the related timer otherwise this races against concurrent timers setting/expiring in the same threadgroup. Detecting that the cputime counter is started without holding the sighand lock is a first step toward debugging such situations. Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210726125513.271824-2-frederic@kernel.org
* posix-cpu-timers: Fix rearm racing against process tickFrederic Weisbecker2021-07-151-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since the process wide cputime counter is started locklessly from posix_cpu_timer_rearm(), it can be concurrently stopped by operations on other timers from the same thread group, such as in the following unlucky scenario: CPU 0 CPU 1 ----- ----- timer_settime(TIMER B) posix_cpu_timer_rearm(TIMER A) cpu_clock_sample_group() (pct->timers_active already true) handle_posix_cpu_timers() check_process_timers() stop_process_timers() pct->timers_active = false arm_timer(TIMER A) tick -> run_posix_cpu_timers() // sees !pct->timers_active, ignore // our TIMER A Fix this with simply locking process wide cputime counting start and timer arm in the same block. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Fixes: 60f2ceaa8111 ("posix-cpu-timers: Remove unnecessary locking around cpu_clock_sample_group") Cc: stable@vger.kernel.org Cc: Oleg Nesterov <oleg@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Eric W. Biederman <ebiederm@xmission.com>
* tick/nohz: Change signal tick dependency to wake up CPUs of member tasksMarcelo Tosatti2021-05-131-2/+2
| | | | | | | | | | | | | Rather than waking up all nohz_full CPUs on the system, only wake up the target CPUs of member threads of the signal. Reduces interruptions to nohz_full CPUs. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20210512232924.150322-8-frederic@kernel.org
* Merge tag 'timers-core-2021-04-26' of ↵Linus Torvalds2021-04-261-3/+3
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer updates from Thomas Gleixner: "The time and timers updates contain: Core changes: - Allow runtime power management when the clocksource is changed. - A correctness fix for clock_adjtime32() so that the return value on success is not overwritten by the result of the copy to user. - Allow late installment of broadcast clockevent devices which was broken because nothing switched them over to oneshot mode. This went unnoticed so far because clockevent devices used to be built in, but now people started to make them modular. - Debugfs related simplifications - Small cleanups and improvements here and there Driver changes: - The usual set of device tree binding updates for a wide range of drivers/devices. - The usual updates and improvements for drivers all over the place but nothing outstanding. - No new clocksource/event drivers. They'll come back next time" * tag 'timers-core-2021-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) posix-timers: Preserve return value in clock_adjtime32() tick/broadcast: Allow late registered device to enter oneshot mode tick: Use tick_check_replacement() instead of open coding it time/timecounter: Mark 1st argument of timecounter_cyc2time() as const dt-bindings: timer: nuvoton,npcm7xx: Add wpcm450-timer clocksource/drivers/arm_arch_timer: Add __ro_after_init and __init clocksource/drivers/timer-ti-dm: Handle dra7 timer wrap errata i940 clocksource/drivers/timer-ti-dm: Prepare to handle dra7 timer wrap issue clocksource/drivers/dw_apb_timer_of: Add handling for potential memory leak clocksource/drivers/npcm: Add support for WPCM450 clocksource/drivers/sh_cmt: Don't use CMTOUT_IE with R-Car Gen2/3 clocksource/drivers/pistachio: Fix trivial typo clocksource/drivers/ingenic_ost: Fix return value check in ingenic_ost_probe() clocksource/drivers/timer-ti-dm: Add missing set_state_oneshot_stopped clocksource/drivers/timer-ti-dm: Fix posted mode status check order dt-bindings: timer: renesas,cmt: Document R8A77961 dt-bindings: timer: renesas,cmt: Add r8a779a0 CMT support clocksource/drivers/ingenic-ost: Add support for the JZ4760B clocksource/drivers/ingenic: Add support for the JZ4760 dt-bindings: timer: ingenic: Add compatible strings for JZ4760(B) ...
| * timekeeping, clocksource: Fix various typos in commentsIngo Molnar2021-03-221-3/+3
| | | | | | | | | | | | | | | | | | | | | | Fix ~56 single-word typos in timekeeping & clocksource code comments. Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Stephen Boyd <sboyd@kernel.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: linux-kernel@vger.kernel.org
* | kernel, fs: Introduce and use set_restart_fn() and arch_set_restart_data()Oleg Nesterov2021-03-161-1/+1
|/ | | | | | | | | | | | | | Preparation for fixing get_nr_restart_syscall() on X86 for COMPAT. Add a new helper which sets restart_block->fn and calls a dummy arch_set_restart_data() helper. Fixes: 609c19a385c8 ("x86/ptrace: Stop setting TS_COMPAT in ptrace code") Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210201174641.GA17871@redhat.com
* posix-cpu-timers: Provide mechanisms to defer timer handling to task_workThomas Gleixner2020-08-061-12/+173
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Running posix CPU timers in hard interrupt context has a few downsides: - For PREEMPT_RT it cannot work as the expiry code needs to take sighand lock, which is a 'sleeping spinlock' in RT. The original RT approach of offloading the posix CPU timer handling into a high priority thread was clumsy and provided no real benefit in general. - For fine grained accounting it's just wrong to run this in context of the timer interrupt because that way a process specific CPU time is accounted to the timer interrupt. - Long running timer interrupts caused by a large amount of expiring timers which can be created and armed by unpriviledged user space. There is no hard requirement to expire them in interrupt context. If the signal is targeted at the task itself then it won't be delivered before the task returns to user space anyway. If the signal is targeted at a supervisor process then it might be slightly delayed, but posix CPU timers are inaccurate anyway due to the fact that they are tied to the tick. Provide infrastructure to schedule task work which allows splitting the posix CPU timer code into a quick check in interrupt context and a thread context expiry and signal delivery function. This has to be enabled by architectures as it requires that the architecture specific KVM implementation handles pending task work before exiting to guest mode. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20200730102337.783470146@linutronix.de
* posix-cpu-timers: Split run_posix_cpu_timers()Thomas Gleixner2020-08-061-19/+24
| | | | | | | | | | | Split it up as a preparatory step to move the heavy lifting out of interrupt context. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20200730102337.677439437@linutronix.de
* posix-cpu-timers: Replace __get_task_for_clock with pid_for_clockEric W. Biederman2020-04-291-45/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now that the codes store references to pids instead of referendes to tasks. Looking up a task for a clock instead of looking up a struct pid makes the code more difficult to verify it is correct than necessary. In posix_cpu_timers_create get_task_pid can race with release_task for threads and return a NULL pid. As put_pid and cpu_timer_task_rcu handle NULL pids just fine the code works without problems but it is an extra case to consider and keep in mind while verifying and modifying the code. There are races with de_thread to consider that only don't apply because thread clocks are only allowed for threads in the same thread_group. So instead of leaving a burden for people making modification to the code in the future return a rcu protected struct pid for the clock instead. The logic for __get_task_for_pid and lookup_task has been folded into the new function pid_for_clock with the only change being the logic has been modified from working on a task to working on a pid that will be returned. In posix_cpu_clock_get instead of calling pid_for_clock checking the result and then calling pid_task to get the task. The result of pid_for_clock is fed directly into pid_task. This is safe because pid_task handles NULL pids. As such an extra error check was unnecessary. Instead of hiding the flag that enables the special clock_gettime handling, I have made the 3 callers just pass the flag in themselves. That is less code and seems just as simple to work with as the wrapper functions. Historically the clock_gettime special case of allowing a process clock to be found by the thread id did not even exist [33ab0fec3352] but Thomas Gleixner reports that he has found code that uses that functionality [55e8c8eb2c7b]. Link: https://lkml.kernel.org/r/87zhaxqkwa.fsf@nanos.tec.linutronix.de/ Ref: 33ab0fec3352 ("posix-timers: Consolidate posix_cpu_clock_get()") Ref: 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* posix-cpu-timers: Replace cpu_timer_pid_type with clock_pid_typeEric W. Biederman2020-04-291-4/+4
| | | | | | | | | | Taking a clock and returning a pid_type is a more general and a superset of taking a timer and returning a pid_type. Perform this generalization so that future changes may use this code on clocks as well as timers. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* posix-cpu-timers: Extend rcu_read_lock removing task_struct referencesEric W. Biederman2020-04-291-20/+23
| | | | | | | | | | Now that the code stores of pid references it is no longer necessary or desirable to take a reference on task_struct in __get_task_for_clock. Instead extend the scope of rcu_read_lock and remove the reference counting on struct task_struct entirely. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* posix-cpu-timer: Unify the now redundant code in lookup_taskEric W. Biederman2020-04-281-8/+7
| | | | | | | | | | | Now that both !thread paths through lookup_task call thread_group_leader, unify them into the single test at the end of lookup_task. This unification just makes it clear what is happening in the gettime special case of lookup_task. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* posix-cpu-timer: Tidy up group_leader logic in lookup_taskEric W. Biederman2020-04-281-6/+2
| | | | | | | | | | | | | | | | | | | | | | | Replace has_group_leader_pid with thread_group_leader. Years ago Oleg suggested changing thread_group_leader to has_group_leader_pid to handle races. Looking at the code then and now I don't see how it ever helped. Especially as then the code really did need to be the thread_group_leader. Today it doesn't make a difference if thread_group_leader races with de_thread as the task returned from lookup_task in the non-thread case is just used to find values in task->signal. Since the races with de_thread have never been handled revert has_group_header_pid to thread_group_leader for clarity. Update the comment in lookup_task to remove implementation details that are no longer true and to mention task->signal instead of task->sighand, as the relevant cpu timer details are all in task->signal. Ref: 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task") Ref: c0deae8c9587 ("posix-cpu-timers: Rcu_read_lock/unlock protect find_task_by_vpid call") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* Merge tag 'timers-core-2020-03-30' of ↵Linus Torvalds2020-03-301-78/+70
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timekeeping and timer updates from Thomas Gleixner: "Core: - Consolidation of the vDSO build infrastructure to address the difficulties of cross-builds for ARM64 compat vDSO libraries by restricting the exposure of header content to the vDSO build. This is achieved by splitting out header content into separate headers. which contain only the minimaly required information which is necessary to build the vDSO. These new headers are included from the kernel headers and the vDSO specific files. - Enhancements to the generic vDSO library allowing more fine grained control over the compiled in code, further reducing architecture specific storage and preparing for adopting the generic library by PPC. - Cleanup and consolidation of the exit related code in posix CPU timers. - Small cleanups and enhancements here and there Drivers: - The obligatory new drivers: Ingenic JZ47xx and X1000 TCU support - Correct the clock rate of PIT64b global clock - setup_irq() cleanup - Preparation for PWM and suspend support for the TI DM timer - Expand the fttmr010 driver to support ast2600 systems - The usual small fixes, enhancements and cleanups all over the place" * tag 'timers-core-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (80 commits) Revert "clocksource/drivers/timer-probe: Avoid creating dead devices" vdso: Fix clocksource.h macro detection um: Fix header inclusion arm64: vdso32: Enable Clang Compilation lib/vdso: Enable common headers arm: vdso: Enable arm to use common headers x86/vdso: Enable x86 to use common headers mips: vdso: Enable mips to use common headers arm64: vdso32: Include common headers in the vdso library arm64: vdso: Include common headers in the vdso library arm64: Introduce asm/vdso/processor.h arm64: vdso32: Code clean up linux/elfnote.h: Replace elf.h with UAPI equivalent scripts: Fix the inclusion order in modpost common: Introduce processor.h linux/ktime.h: Extract common header for vDSO linux/jiffies.h: Extract common header for vDSO linux/time64.h: Extract common header for vDSO linux/time32.h: Extract common header for vDSO linux/time.h: Extract common header for vDSO ...
| * posix-cpu-timers: Store a reference to a pid not a taskEric W. Biederman2020-03-041-18/+55
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | posix cpu timers do not handle the death of a process well. This is most clearly seen when a multi-threaded process calls exec from a thread that is not the leader of the thread group. The posix cpu timer code continues to pin the old thread group leader and is unable to find the siglock from there. This results in posix_cpu_timer_del being unable to delete a timer, posix_cpu_timer_set being unable to set a timer. Further to compensate for the problems in posix_cpu_timer_del on a multi-threaded exec all timers that point at the multi-threaded task are stopped. The code for the timers fundamentally needs to check if the target process/thread is alive. This needs an extra level of indirection. This level of indirection is already available in struct pid. So replace cpu.task with cpu.pid to get the needed extra layer of indirection. In addition to handling things more cleanly this reduces the amount of memory a timer can pin when a process exits and then is reaped from a task_struct to the vastly smaller struct pid. Fixes: e0a70217107e ("posix-cpu-timers: workaround to suppress the problems with mt exec") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/87wo86tz6d.fsf@x220.int.ebiederm.org
| * posix-cpu-timers: Pass the task into arm_timer()Eric W. Biederman2020-03-011-4/+3
| | | | | | | | | | | | | | | | | | | | The task has been already computed to take siglock before calling arm_timer. So pass the benefit of that labor into arm_timer(). Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/8736auvdt1.fsf@x220.int.ebiederm.org
| * posix-cpu-timers: Remove unnecessary locking around cpu_clock_sample_groupEric W. Biederman2020-03-011-54/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | As of e78c3496790e ("time, signal: Protect resource use statistics with seqlock") cpu_clock_sample_group no longers needs siglock protection. Unfortunately no one realized it at the time. Remove the extra locking that is for cpu_clock_sample_group and not for cpu_clock_sample. This significantly simplifies the code. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/878skmvdts.fsf@x220.int.ebiederm.org
| * posix-cpu-timers: cpu_clock_sample_group() no longer needs siglockEric W. Biederman2020-03-011-3/+1
| | | | | | | | | | | | | | | | | | | | As of e78c3496790e ("time, signal: Protect resource use statistics with seqlock") cpu_clock_sample_group() no longer needs siglock protection so remove the stale comment. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/87eeuevduq.fsf@x220.int.ebiederm.org
* | lockdep: Add posixtimer context tracing bitsSebastian Andrzej Siewior2020-03-211-1/+5
|/ | | | | | | | | | | | | | | | | | | | Splitting run_posix_cpu_timers() into two parts is work in progress which is stuck on other entry code related problems. The heavy lifting which involves locking of sighand lock will be moved into task context so the necessary execution time is burdened on the task and not on interrupt context. Until this work completes lockdep with the spinlock nesting rules enabled would emit warnings for this known context. Prevent it by setting "->irq_config = 1" for the invocation of run_posix_cpu_timers() so lockdep does not complain when sighand lock is acquried. This will be removed once the split is completed. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200321113242.751182723@linutronix.de
* posix-clocks: Rename the clock_get() callback to clock_get_timespec()Andrei Vagin2020-01-141-16/+16
| | | | | | | | | | | | | | | | | | | | | | The upcoming support for time namespaces requires to have access to: - The time in a task's time namespace for sys_clock_gettime() - The time in the root name space for common_timer_get() That adds a valid reason to finally implement a separate callback which returns the time in ktime_t format, rather than in (struct timespec). Rename the clock_get() callback to clock_get_timespec() as a preparation for introducing clock_get_ktime(). Suggested-by: Thomas Gleixner <tglx@linutronix.de> Co-developed-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Andrei Vagin <avagin@gmail.com> Signed-off-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20191112012724.250792-6-dima@arista.com
* posix-cpu-timers: Fix two trivial commentsYi Wang2019-10-231-3/+3
| | | | | | | | | | | | | | | | Recent changes modified the function arguments of thread_group_sample_cputime() and task_cputimers_expired(), but forgot to update the comments. Fix it up. [ tglx: Changed the argument name of task_cputimers_expired() as the pointer points to an array of samples. ] Fixes: b7be4ef1365d ("posix-cpu-timers: Switch thread group sampling to array") Fixes: 001f7971433a ("posix-cpu-timers: Make expiry checks array based") Signed-off-by: Yi Wang <wang.yi59@zte.com.cn> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/1571643852-21848-1-git-send-email-wang.yi59@zte.com.cn
* posix-cpu-timers: Fix permission check regressionThomas Gleixner2019-09-101-9/+35
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The recent consolidation of the three permission checks introduced a subtle regression. For timer_create() with a process wide timer it returns the current task if the lookup through the PID which is encoded into the clockid results in returning current. That's broken because it does not validate whether the current task is the group leader. That was caused by the two different variants of permission checks: - posix_cpu_timer_get() allowed access to the process wide clock when the looked up task is current. That's not an issue because the process wide clock is in the shared sighand. - posix_cpu_timer_create() made sure that the looked up task is the group leader. Restore the previous state. Note, that these permission checks are more than questionable, but that's subject to follow up changes. Fixes: 6ae40e3fdcd3 ("posix-cpu-timers: Provide task validation functions") Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1909052314110.1902@nanos.tec.linutronix.de
* posix-cpu-timers: Make expiry_active check actually work correctlyThomas Gleixner2019-08-291-4/+5
| | | | | | | | | | | | | | | | | | | | | | The state tracking changes broke the expiry active check by not writing to it and instead sitting timers_active, which is already set. That's not a big issue as the actual expiry is protected by sighand lock, so concurrent handling is not possible. That means that the second task which invokes that function executes the expiry code for nothing. Write to the proper flag. Also add a check whether the flag is set into check_process_timers(). That check had been missing in the code before the rework already. The check for another task handling the expiry of process wide timers was only done in the fastpath check. If the fastpath check returns true because a per task timer expired, then the checking of process wide timers was done in parallel which is as explained above just a waste of cycles. Fixes: 244d49e30653 ("posix-cpu-timers: Move state tracking to struct posix_cputimers") Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Frederic Weisbecker <frederic@kernel.org>
* posix-cpu-timers: Utilize timerqueue for storageThomas Gleixner2019-08-281-93/+96
| | | | | | | | | | | | | | | | | Using a linear O(N) search for timer insertion affects execution time and D-cache footprint badly with a larger number of timers. Switch the storage to a timerqueue which is already used for hrtimers and alarmtimers. It does not affect the size of struct k_itimer as it.alarm is still larger. The extra list head for the expiry list will go away later once the expiry is moved into task work context. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1908272129220.1939@nanos.tec.linutronix.de
* posix-cpu-timers: Move state tracking to struct posix_cputimersThomas Gleixner2019-08-281-33/+40
| | | | | | | | Put it where it belongs and clean up the ifdeffery in fork completely. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20190821192922.743229404@linutronix.de
* posix-cpu-timers: Deduplicate rlimit handlingThomas Gleixner2019-08-281-42/+25
| | | | | | | | | | | | | Both thread and process expiry functions have the same functionality for sending signals for soft and hard RLIMITs duplicated in 4 different ways. Split it out into a common function and cleanup the callsites. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192922.653276779@linutronix.de
* posix-cpu-timers: Remove pointless comparisonsThomas Gleixner2019-08-281-9/+7
| | | | | | | | | | | | | | The soft RLIMIT expiry code checks whether the soft limit is greater than the hard limit. That's pointless because if the soft RLIMIT is greater than the hard RLIMIT then that code cannot be reached as the hard RLIMIT check is before that and already killed the process. Remove it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192922.548747613@linutronix.de
* posix-cpu-timers: Get rid of 64bit divisionsThomas Gleixner2019-08-281-10/+14
| | | | | | | | | | Instead of dividing A to match the units of B it's more efficient to multiply B to match the units of A. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192922.458286860@linutronix.de
* posix-cpu-timers: Consolidate timer expiry furtherThomas Gleixner2019-08-281-33/+30
| | | | | | | | | | With the array based samples and expiry cache, the expiry function can use a loop to collect timers from the clock specific lists. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192922.365469982@linutronix.de
* posix-cpu-timers: Get rid of zero checksThomas Gleixner2019-08-281-23/+15
| | | | | | | | | | | | | | | | | | | | | | | | Deactivation of the expiry cache is done by setting all clock caches to 0. That requires to have a check for zero in all places which update the expiry cache: if (cache == 0 || new < cache) cache = new; Use U64_MAX as the deactivated value, which allows to remove the zero checks when updating the cache and reduces it to the obvious check: if (new < cache) cache = new; This also removes the weird workaround in do_prlimit() which was required to convert a RLIMIT_CPU value of 0 (immediate expiry) to 1 because handing in 0 to the posix CPU timer code would have effectively disarmed it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192922.275086128@linutronix.de
* posix-cpu-timers: Respect INFINITY for hard RTTIME limitThomas Gleixner2019-08-281-1/+1
| | | | | | | | | | | | | | | | | | | The RTIME limit expiry code does not check the hard RTTIME limit for INFINITY, i.e. being disabled. Add it. While this could be considered an ABI breakage if something would depend on this behaviour. Though it's highly unlikely to have an effect because RLIM_INFINITY is at minimum INT_MAX and the RTTIME limit is in seconds, so the timer would fire after ~68 years. Adding this obvious correct limit check also allows further consolidation of that code and is a prerequisite for cleaning up the 0 based checks and the rlimit setter code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192922.078293002@linutronix.de
* posix-cpu-timers: Switch thread group sampling to arrayThomas Gleixner2019-08-281-59/+45
| | | | | | | | | That allows more simplifications in various places. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192921.988426956@linutronix.de
* posix-cpu-timers: Restructure expiry arrayThomas Gleixner2019-08-281-49/+56
| | | | | | | | | | | | | | | | | Now that the abused struct task_cputime is gone, it's more natural to bundle the expiry cache and the list head of each clock into a struct and have an array of those structs. Follow the hrtimer naming convention of 'bases' and rename the expiry cache to 'nextevt' and adapt all usage sites. Generates also better code .text size shrinks by 80 bytes. Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1908262021140.1939@nanos.tec.linutronix.de
* posix-cpu-timers: Remove cputime_expiresThomas Gleixner2019-08-281-10/+0
| | | | | | | | | | The last users of the magic struct cputime based expiry cache are gone. Remove the leftovers. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192921.790209622@linutronix.de
* posix-cpu-timers: Make expiry checks array basedThomas Gleixner2019-08-281-49/+36
| | | | | | | | | | | | | | | The expiry cache is an array indexed by clock ids. The new sample functions allow to retrieve a corresponding array of samples. Convert the fastpath expiry checks to make use of the new sample functions and do the comparisons on the sample and the expiry array. Make the check for the expiry array being zero array based as well. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192921.695481430@linutronix.de
* posix-cpu-timers: Provide array based sample functionsThomas Gleixner2019-08-281-0/+26
| | | | | | | | | | | Instead of using task_cputime and doing the addition of utime and stime at all call sites, it's way simpler to have a sample array which allows indexed based checks against the expiry cache array. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192921.590362974@linutronix.de
* posix-cpu-timers: Switch check_*_timers() to array cacheThomas Gleixner2019-08-281-15/+11
| | | | | | | | | | Use the array based expiry cache in check_thread_timers() and convert the store in check_process_timers() for consistency. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192921.408222378@linutronix.de
* posix-cpu-timers: Simplify set_process_cpu_timer()Thomas Gleixner2019-08-281-16/+8
| | | | | | | | | | The expiry cache can now be accessed as an array. Replace the per clock checks with a simple comparison of the clock indexed array member. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192921.303316423@linutronix.de
* posix-cpu-timers: Simplify timer queueingThomas Gleixner2019-08-281-34/+21
| | | | | | | | | | Now that the expiry cache can be accessed as an array, the per clock checking can be reduced to just comparing the corresponding array elements. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192921.212129449@linutronix.de
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