eventfd: fold eventfd_ctx_read() into eventfd_read()

eventfd_ctx_read() is not used outside of eventfd.c, so unexport it and
fold it into eventfd_read().  This slightly simplifies the code and
makes it more analogous to eventfd_write().

(eventfd_ctx_read() was apparently added years ago for KVM irqfd's, but
was never used.)

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/eventfd.c b/fs/eventfd.c
index 4167e67..6138d2b 100644 (file)
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -207,36 +207,27 @@ int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *w
 }
 EXPORT_SYMBOL_GPL(eventfd_ctx_remove_wait_queue);
 
-/**
- * eventfd_ctx_read - Reads the eventfd counter or wait if it is zero.
- * @ctx: [in] Pointer to eventfd context.
- * @no_wait: [in] Different from zero if the operation should not block.
- * @cnt: [out] Pointer to the 64-bit counter value.
- *
- * Returns %0 if successful, or the following error codes:
- *
- *  - -EAGAIN      : The operation would have blocked but @no_wait was non-zero.
- *  - -ERESTARTSYS : A signal interrupted the wait operation.
- *
- * If @no_wait is zero, the function might sleep until the eventfd internal
- * counter becomes greater than zero.
- */
-ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt)
+static ssize_t eventfd_read(struct file *file, char __user *buf, size_t count,
+                           loff_t *ppos)
 {
+       struct eventfd_ctx *ctx = file->private_data;
        ssize_t res;
+       __u64 ucnt = 0;
        DECLARE_WAITQUEUE(wait, current);
 
+       if (count < sizeof(ucnt))
+               return -EINVAL;
+
        spin_lock_irq(&ctx->wqh.lock);
-       *cnt = 0;
        res = -EAGAIN;
        if (ctx->count > 0)
-               res = 0;
-       else if (!no_wait) {
+               res = sizeof(ucnt);
+       else if (!(file->f_flags & O_NONBLOCK)) {
                __add_wait_queue(&ctx->wqh, &wait);
                for (;;) {
                        set_current_state(TASK_INTERRUPTIBLE);
                        if (ctx->count > 0) {
-                               res = 0;
+                               res = sizeof(ucnt);
                                break;
                        }
                        if (signal_pending(current)) {
@@ -250,31 +241,17 @@ ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt)
                __remove_wait_queue(&ctx->wqh, &wait);
                __set_current_state(TASK_RUNNING);
        }
-       if (likely(res == 0)) {
-               eventfd_ctx_do_read(ctx, cnt);
+       if (likely(res > 0)) {
+               eventfd_ctx_do_read(ctx, &ucnt);
                if (waitqueue_active(&ctx->wqh))
                        wake_up_locked_poll(&ctx->wqh, POLLOUT);
        }
        spin_unlock_irq(&ctx->wqh.lock);
 
-       return res;
-}
-EXPORT_SYMBOL_GPL(eventfd_ctx_read);
-
-static ssize_t eventfd_read(struct file *file, char __user *buf, size_t count,
-                           loff_t *ppos)
-{
-       struct eventfd_ctx *ctx = file->private_data;
-       ssize_t res;
-       __u64 cnt;
-
-       if (count < sizeof(cnt))
-               return -EINVAL;
-       res = eventfd_ctx_read(ctx, file->f_flags & O_NONBLOCK, &cnt);
-       if (res < 0)
-               return res;
+       if (res > 0 && put_user(ucnt, (__u64 __user *)buf))
+               return -EFAULT;
 
-       return put_user(cnt, (__u64 __user *) buf) ? -EFAULT : sizeof(cnt);
+       return res;
 }
 
 static ssize_t eventfd_write(struct file *file, const char __user *buf, size_t count,

diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h
index 1582619..566fef1 100644 (file)
--- a/include/linux/eventfd.h
+++ b/include/linux/eventfd.h
@@ -36,7 +36,6 @@ struct file *eventfd_fget(int fd);
 struct eventfd_ctx *eventfd_ctx_fdget(int fd);
 struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
 __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
-ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt);
 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
                                  __u64 *cnt);
 
@@ -62,12 +61,6 @@ static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
 
 }
 
-static inline ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait,
-                                      __u64 *cnt)
-{
-       return -ENOSYS;
-}
-
 static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
                                                wait_queue_entry_t *wait, __u64 *cnt)
 {