From: Wen Yang wenyang.linux@foxmail.com
[ Upstream commit 33d8b5d7824c7175ed968b8e89e6db3566e9c177 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- fs/eventfd.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/fs/eventfd.c b/fs/eventfd.c index 6c06a527747f2..8aa36cd373516 100644 --- a/fs/eventfd.c +++ b/fs/eventfd.c @@ -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