public inbox for [email protected]
 help / color / mirror / Atom feed
From: Jens Axboe <[email protected]>
To: io-uring <[email protected]>
Subject: [PATCH] io_uring: don't use poll handler if file can't be nonblocking read/written
Date: Tue, 25 Aug 2020 12:58:17 -0600	[thread overview]
Message-ID: <[email protected]> (raw)

There's no point in using the poll handler if we can't do a nonblocking
IO attempt of the operation, since we'll need to go async anyway. In
fact this is actively harmful, as reading from eg pipes won't return 0
to indicate EOF.

Cc: [email protected] # v5.7+
Signed-off-by: Jens Axboe <[email protected]>

---

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 384df86dfc69..d15139088e4c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4889,12 +4889,20 @@ static bool io_arm_poll_handler(struct io_kiocb *req)
 	struct async_poll *apoll;
 	struct io_poll_table ipt;
 	__poll_t mask, ret;
+	int rw;
 
 	if (!req->file || !file_can_poll(req->file))
 		return false;
 	if (req->flags & REQ_F_POLLED)
 		return false;
-	if (!def->pollin && !def->pollout)
+	if (def->pollin)
+		rw = READ;
+	else if (def->pollout)
+		rw = WRITE;
+	else
+		return false;
+	/* if we can't nonblock try, then no point in arming a poll handler */
+	if (!io_file_supports_async(req->file, rw))
 		return false;
 
 	apoll = kmalloc(sizeof(*apoll), GFP_ATOMIC);

-- 
Jens Axboe


                 reply	other threads:[~2020-08-25 18:58 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    [email protected] \
    [email protected] \
    [email protected] \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox