xen/dev-evtchn: clean up locking in evtchn (0a4666b5) · Commits · 戴 / test

drivers/xen/evtchn.c

+25 −12

Original line number	Diff line number	Diff line
		@@ -54,6 +54,8 @@
		#include <asm/xen/hypervisor.h>

		struct per_user_data {
		struct mutex bind_mutex; /* serialize bind/unbind operations */

		/* Notification ring, accessed via /dev/xen/evtchn. */
		#define EVTCHN_RING_SIZE (PAGE_SIZE / sizeof(evtchn_port_t))
		#define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1))
		@@ -69,7 +71,7 @@ struct per_user_data {

		/* Who's bound to each port? */
		static struct per_user_data *port_user[NR_EVENT_CHANNELS];
		static DEFINE_SPINLOCK(port_user_lock);
		static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */

		irqreturn_t evtchn_interrupt(int irq, void *data)
		{
		@@ -210,22 +212,24 @@ static ssize_t evtchn_write(struct file file, const char __user buf,

		static int evtchn_bind_to_user(struct per_user_data *u, int port)
		{
		int irq;
		int rc = 0;

		spin_lock_irq(&port_user_lock);

		/*
		* Ports are never reused, so every caller should pass in a
		* unique port.
		*
		* (Locking not necessary because we haven't registered the
		* interrupt handler yet, and our caller has already
		* serialized bind operations.)
		*/
		BUG_ON(port_user[port] != NULL);
		port_user[port] = u;

		irq = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED,
		rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED,
		u->name, (void *)(unsigned long)port);
		if (rc < 0)
		goto fail;

		port_user[port] = u;
		if (rc >= 0)
		rc = 0;

		fail:
		spin_unlock_irq(&port_user_lock);
		return rc;
		}

		@@ -234,6 +238,10 @@ static void evtchn_unbind_from_user(struct per_user_data *u, int port)
		int irq = irq_from_evtchn(port);

		unbind_from_irqhandler(irq, (void *)(unsigned long)port);

		/* make sure we unbind the irq handler before clearing the port */
		barrier();

		port_user[port] = NULL;
		}

		@@ -244,6 +252,9 @@ static long evtchn_ioctl(struct file *file,
		struct per_user_data *u = file->private_data;
		void __user uarg = (void __user ) arg;

		/* Prevent bind from racing with unbind */
		mutex_lock(&u->bind_mutex);

		switch (cmd) {
		case IOCTL_EVTCHN_BIND_VIRQ: {
		struct ioctl_evtchn_bind_virq bind;
		@@ -368,6 +379,7 @@ static long evtchn_ioctl(struct file *file,
		rc = -ENOSYS;
		break;
		}
		mutex_unlock(&u->bind_mutex);

		return rc;
		}
		@@ -414,6 +426,7 @@ static int evtchn_open(struct inode inode, struct file filp)
		return -ENOMEM;
		}

		mutex_init(&u->bind_mutex);
		mutex_init(&u->ring_cons_mutex);

		filp->private_data = u;

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