6 files changed, 149 insertions, 42 deletions

diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index d4e8979735cb..9c3138265f8e 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -82,7 +82,7 @@ struct lg_cpu {
 
 struct lg_eventfd {
         unsigned long addr;
-        struct file *event;
+        struct eventfd_ctx *event;
 };
 
 struct lg_eventfd_map {
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 32e297121058..9f9a2953b383 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -50,7 +50,7 @@ static int add_eventfd(struct lguest *lg, unsigned long addr, int fd)
 
         /* Now append new entry. */
         new->map[new->num].addr = addr;
-        new->map[new->num].event = eventfd_fget(fd);
+        new->map[new->num].event = eventfd_ctx_fdget(fd);
         if (IS_ERR(new->map[new->num].event)) {
                 kfree(new);
                 return PTR_ERR(new->map[new->num].event);
@@ -357,7 +357,7 @@ static int close(struct inode *inode, struct file *file)
 
         /* Release any eventfds they registered. */
         for (i = 0; i < lg->eventfds->num; i++)
-                fput(lg->eventfds->map[i].event);
+                eventfd_ctx_put(lg->eventfds->map[i].event);
         kfree(lg->eventfds);
 
         /* If lg->dead doesn't contain an error code it will be NULL or a
diff --git a/fs/aio.c b/fs/aio.c
index 76da12537956..d065b2c3273e 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -485,6 +485,8 @@ static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
 {
         assert_spin_locked(&ctx->ctx_lock);
 
+        if (req->ki_eventfd != NULL)
+                eventfd_ctx_put(req->ki_eventfd);
         if (req->ki_dtor)
                 req->ki_dtor(req);
         if (req->ki_iovec != &req->ki_inline_vec)
@@ -509,8 +511,6 @@ static void aio_fput_routine(struct work_struct *data)
                 /* Complete the fput(s) */
                 if (req->ki_filp != NULL)
                         __fput(req->ki_filp);
-                if (req->ki_eventfd != NULL)
-                        __fput(req->ki_eventfd);
 
                 /* Link the iocb into the context's free list */
                 spin_lock_irq(&ctx->ctx_lock);
@@ -528,8 +528,6 @@ static void aio_fput_routine(struct work_struct *data)
  */
 static int __aio_put_req(struct kioctx *ctx, struct kiocb *req)
 {
-        int schedule_putreq = 0;
-
         dprintk(KERN_DEBUG "aio_put(%p): f_count=%ld\n",
                 req, atomic_long_read(&req->ki_filp->f_count));
 
@@ -549,24 +547,16 @@ static int __aio_put_req(struct kioctx *ctx, struct kiocb *req)
          * we would not be holding the last reference to the file*, so
          * this function will be executed w/out any aio kthread wakeup.
          */
-        if (unlikely(atomic_long_dec_and_test(&req->ki_filp->f_count)))
-                schedule_putreq++;
-        else
-                req->ki_filp = NULL;
-        if (req->ki_eventfd != NULL) {
-                if (unlikely(atomic_long_dec_and_test(&req->ki_eventfd->f_count)))
-                        schedule_putreq++;
-                else
-                        req->ki_eventfd = NULL;
-        }
-        if (unlikely(schedule_putreq)) {
+        if (unlikely(atomic_long_dec_and_test(&req->ki_filp->f_count))) {
                 get_ioctx(ctx);
                 spin_lock(&fput_lock);
                 list_add(&req->ki_list, &fput_head);
                 spin_unlock(&fput_lock);
                 queue_work(aio_wq, &fput_work);
-        } else
+        } else {
+                req->ki_filp = NULL;
                 really_put_req(ctx, req);
+        }
         return 1;
 }
 
@@ -1622,7 +1612,7 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
                  * an eventfd() fd, and will be signaled for each completed
                  * event using the eventfd_signal() function.
                  */
-                req->ki_eventfd = eventfd_fget((int) iocb->aio_resfd);
+                req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
                 if (IS_ERR(req->ki_eventfd)) {
                         ret = PTR_ERR(req->ki_eventfd);
                         req->ki_eventfd = NULL;
diff --git a/fs/eventfd.c b/fs/eventfd.c
index 3f0e1974abdc..31d12de83a2a 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -14,35 +14,44 @@
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/anon_inodes.h>
-#include <linux/eventfd.h>
 #include <linux/syscalls.h>
 #include <linux/module.h>
+#include <linux/kref.h>
+#include <linux/eventfd.h>
 
 struct eventfd_ctx {
+        struct kref kref;
         wait_queue_head_t wqh;
         /*
          * Every time that a write(2) is performed on an eventfd, the
          * value of the __u64 being written is added to "count" and a
          * wakeup is performed on "wqh". A read(2) will return the "count"
          * value to userspace, and will reset "count" to zero. The kernel
-         * size eventfd_signal() also, adds to the "count" counter and
+         * side eventfd_signal() also, adds to the "count" counter and
          * issue a wakeup.
          */
         __u64 count;
         unsigned int flags;
 };
 
-/*
- * Adds "n" to the eventfd counter "count". Returns "n" in case of
- * success, or a value lower then "n" in case of coutner overflow.
- * This function is supposed to be called by the kernel in paths
- * that do not allow sleeping. In this function we allow the counter
- * to reach the ULLONG_MAX value, and we signal this as overflow
- * condition by returining a POLLERR to poll(2).
+/**
+ * eventfd_signal - Adds @n to the eventfd counter.
+ * @ctx: [in] Pointer to the eventfd context.
+ * @n: [in] Value of the counter to be added to the eventfd internal counter.
+ *          The value cannot be negative.
+ *
+ * This function is supposed to be called by the kernel in paths that do not
+ * allow sleeping. In this function we allow the counter to reach the ULLONG_MAX
+ * value, and we signal this as overflow condition by returining a POLLERR
+ * to poll(2).
+ *
+ * Returns @n in case of success, a non-negative number lower than @n in case
+ * of overflow, or the following error codes:
+ *
+ * -EINVAL    : The value of @n is negative.
  */
-int eventfd_signal(struct file *file, int n)
+int eventfd_signal(struct eventfd_ctx *ctx, int n)
 {
-        struct eventfd_ctx *ctx = file->private_data;
         unsigned long flags;
 
         if (n < 0)
@@ -59,9 +68,45 @@ int eventfd_signal(struct file *file, int n)
 }
 EXPORT_SYMBOL_GPL(eventfd_signal);
 
+static void eventfd_free(struct kref *kref)
+{
+        struct eventfd_ctx *ctx = container_of(kref, struct eventfd_ctx, kref);
+
+        kfree(ctx);
+}
+
+/**
+ * eventfd_ctx_get - Acquires a reference to the internal eventfd context.
+ * @ctx: [in] Pointer to the eventfd context.
+ *
+ * Returns: In case of success, returns a pointer to the eventfd context.
+ */
+struct eventfd_ctx *eventfd_ctx_get(struct eventfd_ctx *ctx)
+{
+        kref_get(&ctx->kref);
+        return ctx;
+}
+EXPORT_SYMBOL_GPL(eventfd_ctx_get);
+
+/**
+ * eventfd_ctx_put - Releases a reference to the internal eventfd context.
+ * @ctx: [in] Pointer to eventfd context.
+ *
+ * The eventfd context reference must have been previously acquired either
+ * with eventfd_ctx_get() or eventfd_ctx_fdget()).
+ */
+void eventfd_ctx_put(struct eventfd_ctx *ctx)
+{
+        kref_put(&ctx->kref, eventfd_free);
+}
+EXPORT_SYMBOL_GPL(eventfd_ctx_put);
+
 static int eventfd_release(struct inode *inode, struct file *file)
 {
-        kfree(file->private_data);
+        struct eventfd_ctx *ctx = file->private_data;
+
+        wake_up_poll(&ctx->wqh, POLLHUP);
+        eventfd_ctx_put(ctx);
         return 0;
 }
 
@@ -185,6 +230,16 @@ static const struct file_operations eventfd_fops = {
         .write          = eventfd_write,
 };
 
+/**
+ * eventfd_fget - Acquire a reference of an eventfd file descriptor.
+ * @fd: [in] Eventfd file descriptor.
+ *
+ * Returns a pointer to the eventfd file structure in case of success, or the
+ * following error pointer:
+ *
+ * -EBADF    : Invalid @fd file descriptor.
+ * -EINVAL   : The @fd file descriptor is not an eventfd file.
+ */
 struct file *eventfd_fget(int fd)
 {
         struct file *file;
@@ -201,6 +256,48 @@ struct file *eventfd_fget(int fd)
 }
 EXPORT_SYMBOL_GPL(eventfd_fget);
 
+/**
+ * eventfd_ctx_fdget - Acquires a reference to the internal eventfd context.
+ * @fd: [in] Eventfd file descriptor.
+ *
+ * Returns a pointer to the internal eventfd context, otherwise the error
+ * pointers returned by the following functions:
+ *
+ * eventfd_fget
+ */
+struct eventfd_ctx *eventfd_ctx_fdget(int fd)
+{
+        struct file *file;
+        struct eventfd_ctx *ctx;
+
+        file = eventfd_fget(fd);
+        if (IS_ERR(file))
+                return (struct eventfd_ctx *) file;
+        ctx = eventfd_ctx_get(file->private_data);
+        fput(file);
+
+        return ctx;
+}
+EXPORT_SYMBOL_GPL(eventfd_ctx_fdget);
+
+/**
+ * eventfd_ctx_fileget - Acquires a reference to the internal eventfd context.
+ * @file: [in] Eventfd file pointer.
+ *
+ * Returns a pointer to the internal eventfd context, otherwise the error
+ * pointer:
+ *
+ * -EINVAL   : The @fd file descriptor is not an eventfd file.
+ */
+struct eventfd_ctx *eventfd_ctx_fileget(struct file *file)
+{
+        if (file->f_op != &eventfd_fops)
+                return ERR_PTR(-EINVAL);
+
+        return eventfd_ctx_get(file->private_data);
+}
+EXPORT_SYMBOL_GPL(eventfd_ctx_fileget);
+
 SYSCALL_DEFINE2(eventfd2, unsigned int, count, int, flags)
 {
         int fd;
@@ -217,6 +314,7 @@ SYSCALL_DEFINE2(eventfd2, unsigned int, count, int, flags)
         if (!ctx)
                 return -ENOMEM;
 
+        kref_init(&ctx->kref);
         init_waitqueue_head(&ctx->wqh);
         ctx->count = count;
         ctx->flags = flags;
diff --git a/include/linux/aio.h b/include/linux/aio.h
index b16a957030f8..47f7d932a01d 100644
--- a/include/linux/aio.h
+++ b/include/linux/aio.h
@@ -121,9 +121,9 @@ struct kiocb {
 
         /*
          * If the aio_resfd field of the userspace iocb is not zero,
-         * this is the underlying file* to deliver event to.
+         * this is the underlying eventfd context to deliver events to.
          */
-        struct file             *ki_eventfd;
+        struct eventfd_ctx      *ki_eventfd;
 };
 
 #define is_sync_kiocb(iocb)     ((iocb)->ki_key == KIOCB_SYNC_KEY)
diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h
index f45a8ae5f828..3b85ba6479f4 100644
--- a/include/linux/eventfd.h
+++ b/include/linux/eventfd.h
@@ -8,10 +8,8 @@
 #ifndef _LINUX_EVENTFD_H
 #define _LINUX_EVENTFD_H
 
-#ifdef CONFIG_EVENTFD
-
-/* For O_CLOEXEC and O_NONBLOCK */
 #include <linux/fcntl.h>
+#include <linux/file.h>
 
 /*
  * CAREFUL: Check include/asm-generic/fcntl.h when defining
@@ -27,16 +25,37 @@
 #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
 #define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
 
+#ifdef CONFIG_EVENTFD
+
+struct eventfd_ctx *eventfd_ctx_get(struct eventfd_ctx *ctx);
+void eventfd_ctx_put(struct eventfd_ctx *ctx);
 struct file *eventfd_fget(int fd);
-int eventfd_signal(struct file *file, int n);
+struct eventfd_ctx *eventfd_ctx_fdget(int fd);
+struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
+int eventfd_signal(struct eventfd_ctx *ctx, int n);
 
 #else /* CONFIG_EVENTFD */
 
-#define eventfd_fget(fd) ERR_PTR(-ENOSYS)
-static inline int eventfd_signal(struct file *file, int n)
-{ return 0; }
+/*
+ * Ugly ugly ugly error layer to support modules that uses eventfd but
+ * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
+ */
+static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
+{
+        return ERR_PTR(-ENOSYS);
+}
+
+static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
+{
+        return -ENOSYS;
+}
+
+static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
+{
+
+}
 
-#endif /* CONFIG_EVENTFD */
+#endif
 
 #endif /* _LINUX_EVENTFD_H */