From: Hao Xu <[email protected]>
To: Pavel Begunkov <[email protected]>, Jens Axboe <[email protected]>
Cc: [email protected], Joseph Qi <[email protected]>
Subject: Re: [PATCH 2/2] io_uring: fix race between poll completion and cancel_hash insertion
Date: Wed, 15 Sep 2021 18:50:49 +0800 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
在 2021/9/15 下午6:12, Pavel Begunkov 写道:
> On 9/12/21 5:23 PM, Hao Xu wrote:
>> If poll arming and poll completion runs parallelly, there maybe races.
>> For instance, run io_poll_add in iowq and io_poll_task_func in original
>> context, then:
>> iowq original context
>> io_poll_add
>> vfs_poll
>> (interruption happens
>> tw queued to original
>> context) io_poll_task_func
>> generate cqe
>> del from cancel_hash[]
>> if !poll.done
>> insert to cancel_hash[]
>>
>> The entry left in cancel_hash[], similar case for fast poll.
>> Fix it by set poll.done = true when del from cancel_hash[].
>>
>> Signed-off-by: Hao Xu <[email protected]>
>> ---
>>
>> Didn't find the exact commit to add Fixes: for..
>>
>> fs/io_uring.c | 6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index c16f6be3d46b..988679e5063f 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -5118,10 +5118,8 @@ static bool __io_poll_complete(struct io_kiocb *req, __poll_t mask)
>> }
>> if (req->poll.events & EPOLLONESHOT)
>> flags = 0;
>> - if (!io_cqring_fill_event(ctx, req->user_data, error, flags)) {
>> - req->poll.done = true;
>> + if (!io_cqring_fill_event(ctx, req->user_data, error, flags))
>> flags = 0;
>> - }
>> if (flags & IORING_CQE_F_MORE)
>> ctx->cq_extra++;
>>
>> @@ -5152,6 +5150,7 @@ static void io_poll_task_func(struct io_kiocb *req, bool *locked)
>> if (done) {
>> io_poll_remove_double(req);
>> hash_del(&req->hash_node);
>> + req->poll.done = true;
>> } else {
>> req->result = 0;
>> add_wait_queue(req->poll.head, &req->poll.wait);
>> @@ -5289,6 +5288,7 @@ static void io_async_task_func(struct io_kiocb *req, bool *locked)
>>
>> hash_del(&req->hash_node);
>> io_poll_remove_double(req);
>> + req->poll.done = true;
>
> Only poll request has req->poll. E.g. it overwrites parts of req->rw.kiocb,
> I guess .ki_complete in particular.
>
> struct async_poll *apoll = req->apoll;
> apoll->poll.done = true;
Thanks!
>
>
>> spin_unlock(&ctx->completion_lock);
>>
>> if (!READ_ONCE(apoll->poll.canceled))
>>
>
prev parent reply other threads:[~2021-09-15 10:51 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-12 16:23 [PATCH 0/2] poll fixes Hao Xu
2021-09-12 16:23 ` [PATCH 1/2] io_uring: fix tw list mess-up by adding tw while it's already in tw list Hao Xu
2021-09-15 9:44 ` Pavel Begunkov
2021-09-15 10:48 ` Hao Xu
2021-09-26 9:48 ` Hao Xu
2021-09-29 11:16 ` Pavel Begunkov
2021-09-12 16:23 ` [PATCH 2/2] io_uring: fix race between poll completion and cancel_hash insertion Hao Xu
2021-09-15 9:50 ` Pavel Begunkov
2021-09-15 10:49 ` Hao Xu
2021-09-15 10:12 ` Pavel Begunkov
2021-09-15 10:50 ` Hao Xu [this message]
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 \
--in-reply-to=7db1302e-4064-73db-5c3e-bc98c03e54c4@linux.alibaba.com \
[email protected] \
[email protected] \
[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