[v2] eventfd: show the EFD_SEMAPHORE flag in fdinfo

Commit Message

Wen Yang June 13, 2023, 5:01 p.m. UTC

From: Wen Yang <[e-mail]>

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

Suggested-by: Christian Brauner <[e-mail]>
Signed-off-by: Wen Yang <[e-mail]>
Cc: Alexander Viro <[e-mail]>
Cc: Jens Axboe <[e-mail]>
Cc: Christian Brauner <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Dylan Yudaken <[e-mail]>
Cc: David Woodhouse <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Eric Biggers <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
---
 fs/eventfd.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Comments

Christian Brauner June 14, 2023, 8:09 a.m. UTC | #1

On Wed, 14 Jun 2023 01:01:22 +0800, [e-mail] wrote:
> The EFD_SEMAPHORE flag should be displayed in fdinfo,
> as different value could affect the behavior of eventfd.
> 
> 

Applied to the vfs.misc branch of the vfs/vfs.git tree.
Patches in the vfs.misc branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.misc

[1/1] eventfd: show the EFD_SEMAPHORE flag in fdinfo
      https://git.kernel.org/vfs/vfs/c/33c8c098aaf6

Patch

diff --git a/fs/eventfd.c b/fs/eventfd.c
index 6c06a527747f..8aa36cd37351 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