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eventfd: fold eventfd_ctx_read() into eventfd_read()

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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>
This commit is contained in:
Eric Biggers 2018-01-06 09:45:43 -08:00 committed by Al Viro
parent 7d815165c1
commit b6364572d6
2 changed files with 15 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
fs/eventfd.c
View File

@ -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); EXPORT_SYMBOL_GPL(eventfd_ctx_remove_wait_queue);
/** static ssize_t eventfd_read(struct file *file, char __user *buf, size_t count,
* eventfd_ctx_read - Reads the eventfd counter or wait if it is zero. loff_t *ppos)
* @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)
{ {
struct eventfd_ctx *ctx = file->private_data;
ssize_t res; ssize_t res;
__u64 ucnt = 0;
DECLARE_WAITQUEUE(wait, current); DECLARE_WAITQUEUE(wait, current);
if (count < sizeof(ucnt))
return -EINVAL;
spin_lock_irq(&ctx->wqh.lock); spin_lock_irq(&ctx->wqh.lock);
*cnt = 0;
res = -EAGAIN; res = -EAGAIN;
if (ctx->count > 0) if (ctx->count > 0)
res = 0; res = sizeof(ucnt);
else if (!no_wait) { else if (!(file->f_flags & O_NONBLOCK)) {
__add_wait_queue(&ctx->wqh, &wait); __add_wait_queue(&ctx->wqh, &wait);
for (;;) { for (;;) {
set_current_state(TASK_INTERRUPTIBLE); set_current_state(TASK_INTERRUPTIBLE);
if (ctx->count > 0) { if (ctx->count > 0) {
res = 0; res = sizeof(ucnt);
break; break;
} }
if (signal_pending(current)) { if (signal_pending(current)) {
@ -250,32 +241,18 @@ ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt)
__remove_wait_queue(&ctx->wqh, &wait); __remove_wait_queue(&ctx->wqh, &wait);
__set_current_state(TASK_RUNNING); __set_current_state(TASK_RUNNING);
} }
if (likely(res == 0)) { if (likely(res > 0)) {
eventfd_ctx_do_read(ctx, cnt); eventfd_ctx_do_read(ctx, &ucnt);
if (waitqueue_active(&ctx->wqh)) if (waitqueue_active(&ctx->wqh))
wake_up_locked_poll(&ctx->wqh, POLLOUT); wake_up_locked_poll(&ctx->wqh, POLLOUT);
} }
spin_unlock_irq(&ctx->wqh.lock); spin_unlock_irq(&ctx->wqh.lock);
if (res > 0 && put_user(ucnt, (__u64 __user *)buf))
return -EFAULT;
return res; 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;
return put_user(cnt, (__u64 __user *) buf) ? -EFAULT : sizeof(cnt);
}
static ssize_t eventfd_write(struct file *file, const char __user *buf, size_t count, static ssize_t eventfd_write(struct file *file, const char __user *buf, size_t count,
loff_t *ppos) loff_t *ppos)

7
include/linux/eventfd.h
View File

@ -36,7 +36,6 @@ struct file *eventfd_fget(int fd);
struct eventfd_ctx *eventfd_ctx_fdget(int fd); struct eventfd_ctx *eventfd_ctx_fdget(int fd);
struct eventfd_ctx *eventfd_ctx_fileget(struct file *file); struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n); __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, int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
__u64 *cnt); __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, static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
wait_queue_entry_t *wait, __u64 *cnt) wait_queue_entry_t *wait, __u64 *cnt)
{ {