Commit 33d8b5d7 authored by Wen Yang's avatar Wen Yang Committed by Christian Brauner
Browse files

eventfd: show the EFD_SEMAPHORE flag in fdinfo 



The EFD_SEMAPHORE flag should be displayed in fdinfo,
as different value could affect the behavior of eventfd.

Suggested-by: default avatarChristian Brauner <brauner@kernel.org>
Signed-off-by: default avatarWen Yang <wenyang.linux@foxmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dylan Yudaken <dylany@fb.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Eric Biggers <ebiggers@google.com>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Message-Id: <tencent_05B9CFEFE6B9BC2A9B3A27886A122A7D9205@qq.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 5c075c5b

fs/eventfd.c

+6 −4
Original line number Diff line number Diff line
@@ -33,10 +33,10 @@ struct eventfd_ctx { 
	/*

	 * 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

	 * side eventfd_signal() also, adds to the "count" counter and

	 * issue a wakeup.

	 * wakeup is performed on "wqh". If EFD_SEMAPHORE flag was not

	 * specified, a read(2) will return the "count" value to userspace,

	 * and will reset "count" to zero. The kernel side eventfd_signal()

	 * also, adds to the "count" counter and issue a wakeup.

	 */

	__u64 count;

	unsigned int flags;
@@ -301,6 +301,8 @@ static void eventfd_show_fdinfo(struct seq_file *m, struct file *f) 
		   (unsigned long long)ctx->count);

	spin_unlock_irq(&ctx->wqh.lock);

	seq_printf(m, "eventfd-id: %d\n", ctx->id);

	seq_printf(m, "eventfd-semaphore: %d\n",

		   !!(ctx->flags & EFD_SEMAPHORE));

}

#endif