kernel.git/kernel/irq/manage.c, branch linux-3.16.y

genirq: Fix race on spurious interrupt detection

2019-02-11T17:53:38Z

commit 746a923b863a1065ef77324e1e43f19b1a3eab5c upstream. Commit 1e77d0a1ed74 ("genirq: Sanitize spurious interrupt detection of threaded irqs") made detection of spurious interrupts work for threaded handlers by: a) incrementing a counter every time the thread returns IRQ_HANDLED, and b) checking whether that counter has increased every time the thread is woken. However for oneshot interrupts, the commit unmasks the interrupt before incrementing the counter. If another interrupt occurs right after unmasking but before the counter is incremented, that interrupt is incorrectly considered spurious: time | irq_thread() | irq_thread_fn() | action->thread_fn() | irq_finalize_oneshot() | unmask_threaded_irq() /* interrupt is unmasked */ | | /* interrupt fires, incorrectly deemed spurious */ | | atomic_inc(&desc->threads_handled); /* counter is incremented */ v This is observed with a hi3110 CAN controller receiving data at high volume (from a separate machine sending with "cangen -g 0 -i -x"): The controller signals a huge number of interrupts (hundreds of millions per day) and every second there are about a dozen which are deemed spurious. In theory with high CPU load and the presence of higher priority tasks, the number of incorrectly detected spurious interrupts might increase beyond the 99,900 threshold and cause disablement of the interrupt. In practice it just increments the spurious interrupt count. But that can cause people to waste time investigating it over and over. Fix it by moving the accounting before the invocation of irq_finalize_oneshot(). [ tglx: Folded change log update ] Fixes: 1e77d0a1ed74 ("genirq: Sanitize spurious interrupt detection of threaded irqs") Signed-off-by: Lukas Wunner Signed-off-by: Thomas Gleixner Cc: Mathias Duckeck Cc: Akshay Bhat Cc: Casey Fitzpatrick Link: https://lkml.kernel.org/r/1dfd8bbd16163940648045495e3e9698e63b50ad.1539867047.git.lukas@wunner.de [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings

genirq: Release resources in __setup_irq() error path

2017-09-15T17:30:10Z

commit fa07ab72cbb0d843429e61bf179308aed6cbe0dd upstream. In case __irq_set_trigger() fails the resources requested via irq_request_resources() are not released. Add the missing release call into the error handling path. Fixes: c1bacbae8192 ("genirq: Provide irq_request/release_resources chip callbacks") Signed-off-by: Heiner Kallweit Signed-off-by: Thomas Gleixner Link: http://lkml.kernel.org/r/655538f5-cb20-a892-ff15-fbd2dd1fa4ec@gmail.com Signed-off-by: Ben Hutchings

genirq: Prevent chip buslock deadlock

2016-01-25T10:44:01Z

commit abc7e40c81d113ef4bacb556f0a77ca63ac81d85 upstream. If a interrupt chip utilizes chip->buslock then free_irq() can deadlock in the following way: CPU0 CPU1 interrupt(X) (Shared or spurious) free_irq(X) interrupt_thread(X) chip_bus_lock(X) irq_finalize_oneshot(X) chip_bus_lock(X) synchronize_irq(X) synchronize_irq() waits for the interrupt thread to complete, i.e. forever. Solution is simple: Drop chip_bus_lock() before calling synchronize_irq() as we do with the irq_desc lock. There is nothing to be protected after the point where irq_desc lock has been released. This adds chip_bus_lock/unlock() to the remove_irq() code path, but that's actually correct in the case where remove_irq() is called on such an interrupt. The current users of remove_irq() are not affected as none of those interrupts is on a chip which requires buslock. Reported-by: Fredrik Markström Signed-off-by: Thomas Gleixner Signed-off-by: Luis Henriques

genirq: Sanitize spurious interrupt detection of threaded irqs

2014-05-03T21:15:39Z

Till reported that the spurious interrupt detection of threaded interrupts is broken in two ways: - note_interrupt() is called for each action thread of a shared interrupt line. That's wrong as we are only interested whether none of the device drivers felt responsible for the interrupt, but by calling multiple times for a single interrupt line we account IRQ_NONE even if one of the drivers felt responsible. - note_interrupt() when called from the thread handler is not serialized. That leaves the members of irq_desc which are used for the spurious detection unprotected. To solve this we need to defer the spurious detection of a threaded interrupt to the next hardware interrupt context where we have implicit serialization. If note_interrupt is called with action_ret == IRQ_WAKE_THREAD, we check whether the previous interrupt requested a deferred check. If not, we request a deferred check for the next hardware interrupt and return. If set, we check whether one of the interrupt threads signaled success. Depending on this information we feed the result into the spurious detector. If one primary handler of a shared interrupt returns IRQ_HANDLED we disable the deferred check of irq threads on the same line, as we have found at least one device driver who cared. Reported-by: Till Straumann Signed-off-by: Thomas Gleixner Tested-by: Austin Schuh Cc: Oliver Hartkopp Cc: Wolfgang Grandegger Cc: Pavel Pisa Cc: Marc Kleine-Budde Cc: linux-can@vger.kernel.org Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1303071450130.22263@ionos

genirq: Allow forcing cpu affinity of interrupts

2014-04-17T21:36:27Z

The current implementation of irq_set_affinity() refuses rightfully to route an interrupt to an offline cpu. But there is a special case, where this is actually desired. Some of the ARM SoCs have per cpu timers which require setting the affinity during cpu startup where the cpu is not yet in the online mask. If we can't do that, then the local timer interrupt for the about to become online cpu is routed to some random online cpu. The developers of the affected machines tried to work around that issue, but that results in a massive mess in that timer code. We have a yet unused argument in the set_affinity callbacks of the irq chips, which I added back then for a similar reason. It was never required so it got not used. But I'm happy that I never removed it. That allows us to implement a sane handling of the above scenario. So the affected SoC drivers can add the required force handling to their interrupt chip, switch the timer code to irq_force_affinity() and things just work. This does not affect any existing user of irq_set_affinity(). Tagged for stable to allow a simple fix of the affected SoC clock event drivers. Reported-and-tested-by: Krzysztof Kozlowski Signed-off-by: Thomas Gleixner Cc: Kyungmin Park Cc: Marek Szyprowski Cc: Bartlomiej Zolnierkiewicz Cc: Tomasz Figa , Cc: Daniel Lezcano , Cc: Kukjin Kim Cc: linux-arm-kernel@lists.infradead.org, Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20140416143315.717251504@linutronix.de Signed-off-by: Thomas Gleixner

genirq: Add a new IRQCHIP_EOI_THREADED flag

2014-03-14T12:43:33Z

The flag is necessary for interrupt chips which require an ACK/EOI after the handler has run. In case of threaded handlers this needs to happen after the threaded handler has completed before the unmask of the interrupt. The flag is only unseful in combination with the handle_fasteoi_irq flow control handler. It can be combined with the flag IRQCHIP_EOI_IF_HANDLED, so the EOI is not issued when the interrupt is disabled or in progress. Tested-by: Hans de Goede Reviewed-by: Hans de Goede Cc: linux-arm-kernel@lists.infradead.org Cc: linux-sunxi@googlegroups.com Cc: Maxime Ripard Link: http://lkml.kernel.org/r/1394733834-26839-2-git-send-email-hdegoede@redhat.com Signed-off-by: Thomas Gleixner

Merge branch 'irq/for-gpio' into irq/core

2014-03-12T15:01:07Z

Merge the request/release callbacks which are in a separate branch for consumption by the gpio folks. Signed-off-by: Thomas Gleixner

genirq: Provide irq_request/release_resources chip callbacks

2014-03-12T15:00:24Z

For certain irq types, e.g. gpios, it's necessary to request resources before starting up the irq. This might fail so we cannot use the irq_startup() callback because we might call the irq_set_type() callback before that which does not make sense when the resource is not available. Calling irq_startup() before irq_set_type() can lead to spurious interrupts which is not desired either. Signed-off-by: Thomas Gleixner Cc: Jean-Jacques Hiblot Cc: Grant Likely Cc: linux-arm-kernel@lists.infradead.org Reviewed-by: Linus Walleij Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1403080857160.18573@ionos.tec.linutronix.de Signed-off-by: Thomas Gleixner

genirq: Remove racy waitqueue_active check

2014-02-27T09:54:16Z

We hit one rare case below: T1 calling disable_irq(), but hanging at synchronize_irq() always; The corresponding irq thread is in sleeping state; And all CPUs are in idle state; After analysis, we found there is one possible scenerio which causes T1 is waiting there forever: CPU0 CPU1 synchronize_irq() wait_event() spin_lock() atomic_dec_and_test(&threads_active) insert the __wait into queue spin_unlock() if(waitqueue_active) atomic_read(&threads_active) wake_up() Here after inserted the __wait into queue on CPU0, and before test if queue is empty on CPU1, there is no barrier, it maybe cause it is not visible for CPU1 immediately, although CPU0 has updated the queue list. It is similar for CPU0 atomic_read() threads_active also. So we'd need one smp_mb() before waitqueue_active.that, but removing the waitqueue_active() check solves it as wel l and it makes things simple and clear. Signed-off-by: Chuansheng Liu Cc: Xiaoming Wang Link: http://lkml.kernel.org/r/1393212590-32543-1-git-send-email-chuansheng.liu@intel.com Cc: stable@vger.kernel.org Signed-off-by: Thomas Gleixner

genirq: Update the a comment typo

2014-02-19T16:26:34Z

Change the comment "chasnge" to "change". Signed-off-by: Chuansheng Liu Link: http://lkml.kernel.org/r/1392020037-5484-2-git-send-email-chuansheng.liu@intel.com Signed-off-by: Thomas Gleixner