From: Wen Yang <wenyang.linux@xxxxxxxxxxx>
[ 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@xxxxxxxxxx>
Signed-off-by: Wen Yang <wenyang.linux@xxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Dylan Yudaken <dylany@xxxxxx>
Cc: David Woodhouse <dwmw@xxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Eric Biggers <ebiggers@xxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Message-Id: <tencent_05B9CFEFE6B9BC2A9B3A27886A122A7D9205@xxxxxx>
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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
--
2.39.2
