Re: [PATCH v2 4/4] eventfd: make eventfd_signal{_mask}() void

Jan Kara
2023-11-22T15:06:45Z

On Wed 22-11-23 13:48:25, Christian Brauner wrote:
> No caller care about the return value.
>
> Signed-off-by: Christian Brauner <brauner@kernel.org>

Yup. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

> ---
> fs/eventfd.c | 40 +++++++++++++++-------------------------
> include/linux/eventfd.h | 16 +++++++---------
> 2 files changed, 22 insertions(+), 34 deletions(-)
>
> diff --git a/fs/eventfd.c b/fs/eventfd.c
> index a9a6de920fb4..13be2fb7fc96 100644
> --- a/fs/eventfd.c
> +++ b/fs/eventfd.c
> @@ -43,10 +43,19 @@ struct eventfd_ctx {
> int id;
> };
>
> -__u64 eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask)
> +/**
> + * eventfd_signal - Adds @n to the eventfd counter.
> + * @ctx: [in] Pointer to the eventfd context.
> + * @mask: [in] poll mask
> + *
> + * 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 returning a EPOLLERR
> + * to poll(2).
> + */
> +void eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask)
> {
> unsigned long flags;
> - __u64 n = 1;
>
> /*
> * Deadlock or stack overflow issues can happen if we recurse here
> @@ -57,37 +66,18 @@ __u64 eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask)
> * safe context.
> */
> if (WARN_ON_ONCE(current->in_eventfd))
> - return 0;
> + return;
>
> spin_lock_irqsave(&ctx->wqh.lock, flags);
> current->in_eventfd = 1;
> - if (ULLONG_MAX - ctx->count < n)
> - n = ULLONG_MAX - ctx->count;
> - ctx->count += n;
> + if (ctx->count < ULLONG_MAX)
> + ctx->count++;
> if (waitqueue_active(&ctx->wqh))
> wake_up_locked_poll(&ctx->wqh, EPOLLIN | mask);
> current->in_eventfd = 0;
> spin_unlock_irqrestore(&ctx->wqh.lock, flags);
> -
> - return n == 1;
> -}
> -
> -/**
> - * eventfd_signal - Adds @n to the eventfd counter.
> - * @ctx: [in] Pointer to the eventfd context.
> - *
> - * 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 returning a EPOLLERR
> - * to poll(2).
> - *
> - * Returns the amount by which the counter was incremented.
> - */
> -__u64 eventfd_signal(struct eventfd_ctx *ctx)
> -{
> - return eventfd_signal_mask(ctx, 0);
> }
> -EXPORT_SYMBOL_GPL(eventfd_signal);
> +EXPORT_SYMBOL_GPL(eventfd_signal_mask);
>
> static void eventfd_free_ctx(struct eventfd_ctx *ctx)
> {
> diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h
> index 4f8aac7eb62a..fea7c4eb01d6 100644
> --- a/include/linux/eventfd.h
> +++ b/include/linux/eventfd.h
> @@ -35,8 +35,7 @@ void eventfd_ctx_put(struct eventfd_ctx *ctx);
> 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 eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask);
> +void eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask);
> int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
> __u64 *cnt);
> void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
> @@ -58,14 +57,8 @@ static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
> return ERR_PTR(-ENOSYS);
> }
>
> -static inline int eventfd_signal(struct eventfd_ctx *ctx)
> +static inline void eventfd_signal_mask(struct eventfd_ctx *ctx, unsigned mask)
> {
> - return -ENOSYS;
> -}
> -
> -static inline int eventfd_signal_mask(struct eventfd_ctx *ctx, unsigned mask)
> -{
> - return -ENOSYS;
> }
>
> static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
> @@ -91,5 +84,10 @@ static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
>
> #endif
>
> +static inline void eventfd_signal(struct eventfd_ctx *ctx)
> +{
> + eventfd_signal_mask(ctx, 0);
> +}
> +
> #endif /* _LINUX_EVENTFD_H */
>
>
> --
> 2.42.0
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR