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Subject[PATCH 2/3] eventfd: fold eventfd_ctx_read() into eventfd_read()
Date
From: Eric Biggers <ebiggers@google.com>

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>
---
fs/eventfd.c | 53 ++++++++++++++-----------------------------------
include/linux/eventfd.h | 7 -------
2 files changed, 15 insertions(+), 45 deletions(-)

diff --git a/fs/eventfd.c b/fs/eventfd.c
index 4167e670ed4d..6138d2b5cdeb 100644
--- 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 15826192cc23..566fef14d0a6 100644
--- 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)
{
--
2.15.1
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