user/sven/linux.git/include/linux/interrupt.h, branch v5.13.16

tasklets: Switch tasklet_disable() to the sleep wait variant

2021-03-17T15:34:07Z

-- NOT FOR IMMEDIATE MERGING -- Now that all users of tasklet_disable() are invoked from sleepable context, convert it to use tasklet_unlock_wait() which might sleep. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20210309084242.726452321@linutronix.de

tasklets: Prevent tasklet_unlock_spin_wait() deadlock on RT

2021-03-17T15:33:57Z

tasklet_unlock_spin_wait() spin waits for the TASKLET_STATE_SCHED bit in the tasklet state to be cleared. This works on !RT nicely because the corresponding execution can only happen on a different CPU. On RT softirq processing is preemptible, therefore a task preempting the softirq processing thread can spin forever. Prevent this by invoking local_bh_disable()/enable() inside the loop. In case that the softirq processing thread was preempted by the current task, current will block on the local lock which yields the CPU to the preempted softirq processing thread. If the tasklet is processed on a different CPU then the local_bh_disable()/enable() pair is just a waste of processor cycles. Signed-off-by: Thomas Gleixner Tested-by: Sebastian Andrzej Siewior Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20210309084241.988908275@linutronix.de

tasklets: Replace spin wait in tasklet_unlock_wait()

2021-03-17T15:33:55Z

tasklet_unlock_wait() spin waits for TASKLET_STATE_RUN to be cleared. This is wasting CPU cycles in a tight loop which is especially painful in a guest when the CPU running the tasklet is scheduled out. tasklet_unlock_wait() is invoked from tasklet_kill() which is used in teardown paths and not performance critical at all. Replace the spin wait with wait_var_event(). There are no users of tasklet_unlock_wait() which are invoked from atomic contexts. The usage in tasklet_disable() has been replaced temporarily with the spin waiting variant until the atomic users are fixed up and will be converted to the sleep wait variant later. Signed-off-by: Peter Zijlstra Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20210309084241.783936921@linutronix.de

tasklets: Use spin wait in tasklet_disable() temporarily

2021-03-17T15:33:54Z

To ease the transition use spin waiting in tasklet_disable() until all usage sites from atomic context have been cleaned up. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20210309084241.685352806@linutronix.de

tasklets: Provide tasklet_disable_in_atomic()

2021-03-17T15:33:52Z

Replacing the spin wait loops in tasklet_unlock_wait() with wait_var_event() is not possible as a handful of tasklet_disable() invocations are happening in atomic context. All other invocations are in teardown paths which can sleep. Provide tasklet_disable_in_atomic() and tasklet_unlock_spin_wait() to convert the few atomic use cases over, which allows to change tasklet_disable() and tasklet_unlock_wait() in a later step. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20210309084241.563164193@linutronix.de

tasklets: Use static inlines for stub implementations

2021-03-17T15:33:51Z

Inlines exist for a reason. Signed-off-by: Thomas Gleixner Tested-by: Sebastian Andrzej Siewior Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20210309084241.407702697@linutronix.de

tasklets: Replace barrier() with cpu_relax() in tasklet_unlock_wait()

2021-03-17T15:33:51Z

A barrier() in a tight loop which waits for something to happen on a remote CPU is a pointless exercise. Replace it with cpu_relax() which allows HT siblings to make progress. Signed-off-by: Thomas Gleixner Tested-by: Sebastian Andrzej Siewior Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20210309084241.249343366@linutronix.de

tasklet: Remove tasklet_kill_immediate

2021-03-16T14:06:31Z

Ever since RCU was converted to softirq, it has no users. Signed-off-by: Davidlohr Bueso Signed-off-by: Thomas Gleixner Acked-by: Paul E. McKenney Link: https://lore.kernel.org/r/20210306213658.12862-1-dave@stgolabs.net

genirq: Add IRQF_NO_AUTOEN for request_irq/nmi()

2021-03-06T11:48:00Z

Many drivers don't want interrupts enabled automatically via request_irq(). So they are handling this issue by either way of the below two: (1) irq_set_status_flags(irq, IRQ_NOAUTOEN); request_irq(dev, irq...); (2) request_irq(dev, irq...); disable_irq(irq); The code in the second way is silly and unsafe. In the small time gap between request_irq() and disable_irq(), interrupts can still come. The code in the first way is safe though it's subobtimal. Add a new IRQF_NO_AUTOEN flag which can be handed in by drivers to request_irq() and request_nmi(). It prevents the automatic enabling of the requested interrupt/nmi in the same safe way as #1 above. With that the various usage sites of #1 and #2 above can be simplified and corrected. Signed-off-by: Barry Song Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar Cc: dmitry.torokhov@gmail.com Link: https://lore.kernel.org/r/20210302224916.13980-2-song.bao.hua@hisilicon.com

softirq: Move do_softirq_own_stack() to generic asm header

2021-02-10T22:34:16Z

To avoid include recursion hell move the do_softirq_own_stack() related content into a generic asm header and include it from all places in arch/ which need the prototype. This allows architectures to provide an inline implementation of do_softirq_own_stack() without introducing a lot of #ifdeffery all over the place. Signed-off-by: Thomas Gleixner Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20210210002513.289960691@linutronix.de