linux/kernel/rcu, branch v5.8

Merge tag 'core-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-07-05T19:21:28Z

Pull rcu fixlet from Thomas Gleixner: "A single fix for a printk format warning in RCU" * tag 'core-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: rcuperf: Fix printk format warning

rcu: Fixup noinstr warnings

2020-06-25T15:24:32Z

A KCSAN build revealed we have explicit annoations through atomic_*() usage, switch to arch_atomic_*() for the respective functions. vmlinux.o: warning: objtool: rcu_nmi_exit()+0x4d: call to __kcsan_check_access() leaves .noinstr.text section vmlinux.o: warning: objtool: rcu_dynticks_eqs_enter()+0x25: call to __kcsan_check_access() leaves .noinstr.text section vmlinux.o: warning: objtool: rcu_nmi_enter()+0x4f: call to __kcsan_check_access() leaves .noinstr.text section vmlinux.o: warning: objtool: rcu_dynticks_eqs_exit()+0x2a: call to __kcsan_check_access() leaves .noinstr.text section vmlinux.o: warning: objtool: __rcu_is_watching()+0x25: call to __kcsan_check_access() leaves .noinstr.text section Additionally, without the NOP in instrumentation_begin(), objtool would not detect the lack of the 'else instrumentation_begin();' branch in rcu_nmi_enter(). Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Paul E. McKenney

Merge tag 'tty-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

2020-06-07T16:52:36Z

Pull tty/serial driver updates from Greg KH: "Here is the tty and serial driver updates for 5.8-rc1 Nothing huge at all, just a lot of little serial driver fixes, updates for new devices and features, and other small things. Full details are in the shortlog. All of these have been in linux-next with no issues for a while" * tag 'tty-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (67 commits) tty: serial: qcom_geni_serial: Add 51.2MHz frequency support tty: serial: imx: clear Ageing Timer Interrupt in handler serial: 8250_fintek: Add F81966 Support sc16is7xx: Add flag to activate IrDA mode dt-bindings: sc16is7xx: Add flag to activate IrDA mode serial: 8250: Support rs485 bus termination GPIO serial: 8520_port: Fix function param documentation dt-bindings: serial: Add binding for rs485 bus termination GPIO vt: keyboard: avoid signed integer overflow in k_ascii serial: 8250: Enable 16550A variants by default on non-x86 tty: hvc_console, fix crashes on parallel open/close serial: imx: Initialize lock for non-registered console sc16is7xx: Read the LSR register for basic device presence check sc16is7xx: Allow sharing the IRQ line sc16is7xx: Use threaded IRQ sc16is7xx: Always use falling edge IRQ tty: n_gsm: Fix bogus i++ in gsm_data_kick tty: n_gsm: Remove unnecessary test in gsm_print_packet() serial: stm32: add no_console_suspend support tty: serial: fsl_lpuart: Use __maybe_unused instead of #if CONFIG_PM_SLEEP ...

Merge branch 'urgent-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/urgent

2020-06-03T09:14:37Z

Pull RCU fix from Paul E. McKenney. Signed-off-by: Ingo Molnar

rcuperf: Fix printk format warning

2020-06-02T15:41:37Z

Using "%zu" to fix following warning, kernel/rcu/rcuperf.c: In function ‘kfree_perf_init’: include/linux/kern_levels.h:5:18: warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 2 has type ‘unsigned int’ [-Wformat=] Signed-off-by: Kefeng Wang Signed-off-by: Paul E. McKenney

Merge branch 'WIP.core/rcu' into core/rcu, to pick up two x86/entry dependencies

2020-06-01T09:47:29Z

Signed-off-by: Ingo Molnar

rcu: Allow for smp_call_function() running callbacks from idle

2020-05-28T08:50:12Z

Current RCU hard relies on smp_call_function() callbacks running from interrupt context. A pending optimization is going to break that, it will allow idle CPUs to run the callbacks from the idle loop. This avoids raising the IPI on the requesting CPU and avoids handling an exception on the receiving CPU. Change rcu_is_cpu_rrupt_from_idle() to also accept task context, provided it is the idle task. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Paul E. McKenney Reviewed-by: Joel Fernandes (Google) Link: https://lore.kernel.org/r/20200527171236.GC706495@hirez.programming.kicks-ass.net

rcu: Provide rcu_irq_exit_check_preempt()

2020-05-26T17:05:11Z

Provide a debug check which can be invoked from exception return to kernel mode before an attempt is made to schedule. Warn if RCU is not ready for this. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar Cc: Paul E. McKenney Link: https://lore.kernel.org/r/20200521202117.089709607@linutronix.de

rcu: Abstract out rcu_irq_enter_check_tick() from rcu_nmi_enter()

2020-05-26T17:04:18Z

There will likely be exception handlers that can sleep, which rules out the usual approach of invoking rcu_nmi_enter() on entry and also rcu_nmi_exit() on all exit paths. However, the alternative approach of just not calling anything can prevent RCU from coaxing quiescent states from nohz_full CPUs that are looping in the kernel: RCU must instead IPI them explicitly. It would be better to enable the scheduler tick on such CPUs to interact with RCU in a lighter-weight manner, and this enabling is one of the things that rcu_nmi_enter() currently does. What is needed is something that helps RCU coax quiescent states while not preventing subsequent sleeps. This commit therefore splits out the nohz_full scheduler-tick enabling from the rest of the rcu_nmi_enter() logic into a new function named rcu_irq_enter_check_tick(). [ tglx: Renamed the function and made it a nop when context tracking is off ] [ mingo: Fixed a CONFIG_NO_HZ_FULL assumption, harmonized and fixed all the comment blocks and cleaned up rcu_nmi_enter()/exit() definitions. ] Suggested-by: Andy Lutomirski Signed-off-by: Paul E. McKenney Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200521202116.996113173@linutronix.de

rcu: Provide __rcu_is_watching()

2020-05-19T13:51:21Z

Same as rcu_is_watching() but without the preempt_disable/enable() pair inside the function. It is merked noinstr so it ends up in the non-instrumentable text section. This is useful for non-preemptible code especially in the low level entry section. Using rcu_is_watching() there results in a call to the preempt_schedule_notrace() thunk which triggers noinstr section warnings in objtool. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra Link: https://lkml.kernel.org/r/20200512213810.518709291@linutronix.de