On 3/6/23 3:50 AM, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
>
> The patch below does not apply to the 6.1-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
This patch just needs:
df730ec21f7b ("io_uring: fix two assignments in if conditions")
cherry picked first. I'm attaching that one, and the one from this email,
they will apply directly to 6.1-stable. Or you can just cherry-pick
them as that'll work too, as long as you do df730ec21f7b first. Thanks!
--
Jens Axboe
From 1338516e9621c40023de72e02a4130912c7771c3 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@xxxxxxxxx>
Date: Sat, 25 Feb 2023 12:53:53 -0700
Subject: [PATCH 2/2] io_uring/poll: allow some retries for poll triggering
spuriously
commit c16bda37594f83147b167d381d54c010024efecf upstream.
If we get woken spuriously when polling and fail the operation with
-EAGAIN again, then we generally only allow polling again if data
had been transferred at some point. This is indicated with
REQ_F_PARTIAL_IO. However, if the spurious poll triggers when the socket
was originally empty, then we haven't transferred data yet and we will
fail the poll re-arm. This either punts the socket to io-wq if it's
blocking, or it fails the request with -EAGAIN if not. Neither condition
is desirable, as the former will slow things down, while the latter
will make the application confused.
We want to ensure that a repeated poll trigger doesn't lead to infinite
work making no progress, that's what the REQ_F_PARTIAL_IO check was
for. But it doesn't protect against a loop post the first receive, and
it's unnecessarily strict if we started out with an empty socket.
Add a somewhat random retry count, just to put an upper limit on the
potential number of retries that will be done. This should be high enough
that we won't really hit it in practice, unless something needs to be
aborted anyway.
Cc: stable@xxxxxxxxxxxxxxx # v5.10+
Link: https://github.com/axboe/liburing/issues/364
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
io_uring/poll.c | 14 ++++++++++++--
io_uring/poll.h | 1 +
2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/io_uring/poll.c b/io_uring/poll.c
index 8aa9dd9e504a..56dbd1863c78 100644
--- a/io_uring/poll.c
+++ b/io_uring/poll.c
@@ -668,6 +668,14 @@ static void io_async_queue_proc(struct file *file, struct wait_queue_head *head,
__io_queue_proc(&apoll->poll, pt, head, &apoll->double_poll);
}
+/*
+ * We can't reliably detect loops in repeated poll triggers and issue
+ * subsequently failing. But rather than fail these immediately, allow a
+ * certain amount of retries before we give up. Given that this condition
+ * should _rarely_ trigger even once, we should be fine with a larger value.
+ */
+#define APOLL_MAX_RETRY 128
+
static struct async_poll *io_req_alloc_apoll(struct io_kiocb *req,
unsigned issue_flags)
{
@@ -683,14 +691,18 @@ static struct async_poll *io_req_alloc_apoll(struct io_kiocb *req,
if (entry == NULL)
goto alloc_apoll;
apoll = container_of(entry, struct async_poll, cache);
+ apoll->poll.retries = APOLL_MAX_RETRY;
} else {
alloc_apoll:
apoll = kmalloc(sizeof(*apoll), GFP_ATOMIC);
if (unlikely(!apoll))
return NULL;
+ apoll->poll.retries = APOLL_MAX_RETRY;
}
apoll->double_poll = NULL;
req->apoll = apoll;
+ if (unlikely(!--apoll->poll.retries))
+ return NULL;
return apoll;
}
@@ -712,8 +724,6 @@ int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags)
return IO_APOLL_ABORTED;
if (!file_can_poll(req->file))
return IO_APOLL_ABORTED;
- if ((req->flags & (REQ_F_POLLED|REQ_F_PARTIAL_IO)) == REQ_F_POLLED)
- return IO_APOLL_ABORTED;
if (!(req->flags & REQ_F_APOLL_MULTISHOT))
mask |= EPOLLONESHOT;
diff --git a/io_uring/poll.h b/io_uring/poll.h
index 5f3bae50fc81..b2393b403a2c 100644
--- a/io_uring/poll.h
+++ b/io_uring/poll.h
@@ -12,6 +12,7 @@ struct io_poll {
struct file *file;
struct wait_queue_head *head;
__poll_t events;
+ int retries;
struct wait_queue_entry wait;
};
--
2.39.2
From 59a5df2274807288547a740fd2bc258a58944396 Mon Sep 17 00:00:00 2001
From: Xinghui Li <korantli@xxxxxxxxxxx>
Date: Wed, 2 Nov 2022 16:25:03 +0800
Subject: [PATCH 1/2] io_uring: fix two assignments in if conditions
commit df730ec21f7ba395b1b22e7f93a3a85b1d1b7882 upstream.
Fixes two errors:
"ERROR: do not use assignment in if condition
130: FILE: io_uring/net.c:130:
+ if (!(issue_flags & IO_URING_F_UNLOCKED) &&
ERROR: do not use assignment in if condition
599: FILE: io_uring/poll.c:599:
+ } else if (!(issue_flags & IO_URING_F_UNLOCKED) &&"
reported by checkpatch.pl in net.c and poll.c .
Signed-off-by: Xinghui Li <korantli@xxxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Link: https://lore.kernel.org/r/20221102082503.32236-1-korantwork@xxxxxxxxx
[axboe: style tweaks]
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
io_uring/net.c | 16 +++++++++-------
io_uring/poll.c | 7 +++++--
2 files changed, 14 insertions(+), 9 deletions(-)
diff --git a/io_uring/net.c b/io_uring/net.c
index 520a73b5a448..e7e4ec16337d 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -126,13 +126,15 @@ static struct io_async_msghdr *io_msg_alloc_async(struct io_kiocb *req,
struct io_cache_entry *entry;
struct io_async_msghdr *hdr;
- if (!(issue_flags & IO_URING_F_UNLOCKED) &&
- (entry = io_alloc_cache_get(&ctx->netmsg_cache)) != NULL) {
- hdr = container_of(entry, struct io_async_msghdr, cache);
- hdr->free_iov = NULL;
- req->flags |= REQ_F_ASYNC_DATA;
- req->async_data = hdr;
- return hdr;
+ if (!(issue_flags & IO_URING_F_UNLOCKED)) {
+ entry = io_alloc_cache_get(&ctx->netmsg_cache);
+ if (entry) {
+ hdr = container_of(entry, struct io_async_msghdr, cache);
+ hdr->free_iov = NULL;
+ req->flags |= REQ_F_ASYNC_DATA;
+ req->async_data = hdr;
+ return hdr;
+ }
}
if (!io_alloc_async_data(req)) {
diff --git a/io_uring/poll.c b/io_uring/poll.c
index ab5ae475840f..8aa9dd9e504a 100644
--- a/io_uring/poll.c
+++ b/io_uring/poll.c
@@ -678,10 +678,13 @@ static struct async_poll *io_req_alloc_apoll(struct io_kiocb *req,
if (req->flags & REQ_F_POLLED) {
apoll = req->apoll;
kfree(apoll->double_poll);
- } else if (!(issue_flags & IO_URING_F_UNLOCKED) &&
- (entry = io_alloc_cache_get(&ctx->apoll_cache)) != NULL) {
+ } else if (!(issue_flags & IO_URING_F_UNLOCKED)) {
+ entry = io_alloc_cache_get(&ctx->apoll_cache);
+ if (entry == NULL)
+ goto alloc_apoll;
apoll = container_of(entry, struct async_poll, cache);
} else {
+alloc_apoll:
apoll = kmalloc(sizeof(*apoll), GFP_ATOMIC);
if (unlikely(!apoll))
return NULL;
--
2.39.2
