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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: Christian Brauner <brauner@kernel.org>
Signed-off-by: Wen 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: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Wen Yang 2023-06-14 01:01:22 +08:00 committed by Christian Brauner
parent 5c075c5b8f
commit 33d8b5d782
1 changed files with 6 additions and 4 deletions
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10
fs/eventfd.c
View File

@ -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