kernel.git/drivers/xen/evtchn.c, branch linux-4.3.y

xen/evtchn: support more than 4096 ports

2014-01-06T15:07:50Z

Remove the check during unbind for NR_EVENT_CHANNELS as this limits support to less than 4096 ports. Signed-off-by: David Vrabel Reviewed-by: Konrad Rzeszutek Wilk Reviewed-by: Boris Ostrovsky

xen: remove deprecated IRQF_DISABLED

2013-11-06T20:31:16Z

This patch proposes to remove the IRQF_DISABLED flag from drivers/xen code. It's a NOOP since 2.6.35 and it will be removed one day. Note that architecture dependent fixes for IRQF_DISABLED were already submitted through separate patches. Signed-off-by: Michael Opdenacker Signed-off-by: Konrad Rzeszutek Wilk

xen/evtchn: double free on error

2013-08-30T12:44:53Z

The call to del_evtchn() frees "evtchn". Signed-off-by: Dan Carpenter Signed-off-by: Konrad Rzeszutek Wilk

xen/evtchn: improve scalability by using per-user locks

2013-08-09T15:06:49Z

The global array of port users and the port_user_lock limits scalability of the evtchn device. Instead of the global array lookup, use a per-use (per-fd) tree of event channels bound by that user and protect the tree with a per-user lock. This is also a prerequiste for extended the number of supported event channels, by removing the fixed size, per-event channel array. Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk

xen/evtchn: avoid a deadlock when unbinding an event channel

2013-07-30T13:21:14Z

Unbinding an event channel (either with the ioctl or when the evtchn device is closed) may deadlock because disable_irq() is called with port_user_lock held which is also locked by the interrupt handler. Think of the IOCTL_EVTCHN_UNBIND is being serviced, the routine has just taken the lock, and an interrupt happens. The evtchn_interrupt is invoked, tries to take the lock and spins forever. A quick glance at the code shows that the spinlock is a local IRQ variant. Unfortunately that does not help as "disable_irq() waits for the interrupt handler on all CPUs to stop running. If the irq occurs on another VCPU, it tries to take port_user_lock and can't because the unbind ioctl is holding it." (from David). Hence we cannot depend on the said spinlock to protect us. We could make it a system wide IRQ disable spinlock but there is a better way. We can piggyback on the fact that the existence of the spinlock is to make get_port_user() checks be up-to-date. And we can alter those checks to not depend on the spin lock (as it's protected by u->bind_mutex in the ioctl) and can remove the unnecessary locking (this is IOCTL_EVTCHN_UNBIND) path. In the interrupt handler we cannot use the mutex, but we do not need it. "The unbind disables the irq before making the port user stale, so when you clear it you are guaranteed that the interrupt handler that might use that port cannot be running." (from David). Hence this patch removes the spinlock usage on the teardown path and piggybacks on disable_irq happening before we muck with the get_port_user() data. This ensures that the interrupt handler will never run on stale data. Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk [v1: Expanded the commit description a bit]

xen: Convert printks to pr_

2013-06-28T15:19:58Z

Convert printks to pr_ (excludes printk(KERN_DEBUG...) to be more consistent throughout the xen subsystem. Add pr_fmt with KBUILD_MODNAME or "xen:" KBUILD_MODNAME Coalesce formats and add missing word spaces Add missing newlines Align arguments and reflow to 80 columns Remove DRV_NAME from formats as pr_fmt adds the same content This does change some of the prefixes of these messages but it also does make them more consistent. Signed-off-by: Joe Perches Signed-off-by: Konrad Rzeszutek Wilk

xen: close evtchn port if binding to irq fails

2013-02-20T03:02:33Z

CC: stable@vger.kernel.org Signed-off-by: Wei Liu Signed-off-by: Konrad Rzeszutek Wilk

xen-evtchn: correct comment and error output

2013-02-20T03:02:32Z

The evtchn device has been moved to /dev/xen. Also change log level to KERN_ERR as other xen drivers. Signed-off-by: Wei Liu Signed-off-by: Konrad Rzeszutek Wilk

xen/event: Add reference counting to event channels

2011-11-21T22:14:48Z

Event channels exposed to userspace by the evtchn module may be used by other modules in an asynchronous manner, which requires that reference counting be used to prevent the event channel from being closed before the signals are delivered. The reference count on new event channels defaults to -1 which indicates the event channel is not referenced outside the kernel; evtchn_get fails if called on such an event channel. The event channels made visible to userspace by evtchn have a normal reference count. Signed-off-by: Daniel De Graaf Signed-off-by: Konrad Rzeszutek Wilk

treewide: remove extra semicolons

2011-04-10T15:01:05Z

Signed-off-by: Justin P. Mattock Signed-off-by: Jiri Kosina