* [PATCH] io_uring: don't hold fixed_file_data's lock when registering files
@ 2020-09-02 11:32 Xiaoguang Wang
2020-09-02 14:13 ` Jens Axboe
0 siblings, 1 reply; 4+ messages in thread
From: Xiaoguang Wang @ 2020-09-02 11:32 UTC (permalink / raw)
To: io-uring; +Cc: axboe, joseph.qi, Xiaoguang Wang
While registering new files by IORING_REGISTER_FILES, there're not
valid fixed_file_ref_node at the moment, so it's unnecessary to hold
fixed_file_data's lock when registering files.
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
---
fs/io_uring.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 186072861af9..75841f3cb2f7 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7257,9 +7257,7 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
}
ctx->file_data->cur_refs = &ref_node->refs;
- spin_lock(&ctx->file_data->lock);
list_add(&ref_node->node, &ctx->file_data->ref_list);
- spin_unlock(&ctx->file_data->lock);
percpu_ref_get(&ctx->file_data->refs);
return ret;
}
--
2.17.2
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] io_uring: don't hold fixed_file_data's lock when registering files
2020-09-02 11:32 [PATCH] io_uring: don't hold fixed_file_data's lock when registering files Xiaoguang Wang
@ 2020-09-02 14:13 ` Jens Axboe
2020-09-03 4:35 ` Xiaoguang Wang
0 siblings, 1 reply; 4+ messages in thread
From: Jens Axboe @ 2020-09-02 14:13 UTC (permalink / raw)
To: Xiaoguang Wang, io-uring; +Cc: joseph.qi
On 9/2/20 5:32 AM, Xiaoguang Wang wrote:
> While registering new files by IORING_REGISTER_FILES, there're not
> valid fixed_file_ref_node at the moment, so it's unnecessary to hold
> fixed_file_data's lock when registering files.
Even if that were the case (I haven't looked too closely at it yet),
it would a) need a big comment explaining why, and b) some justification
on why this would be a change we'd want to make.
On b, are you seeing any tangible differences with this?
--
Jens Axboe
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] io_uring: don't hold fixed_file_data's lock when registering files
2020-09-02 14:13 ` Jens Axboe
@ 2020-09-03 4:35 ` Xiaoguang Wang
2020-09-03 11:40 ` Jens Axboe
0 siblings, 1 reply; 4+ messages in thread
From: Xiaoguang Wang @ 2020-09-03 4:35 UTC (permalink / raw)
To: Jens Axboe, io-uring; +Cc: joseph.qi
hi，
> On 9/2/20 5:32 AM, Xiaoguang Wang wrote:
>> While registering new files by IORING_REGISTER_FILES, there're not
>> valid fixed_file_ref_node at the moment, so it's unnecessary to hold
>> fixed_file_data's lock when registering files.
>
> Even if that were the case (I haven't looked too closely at it yet),
> it would a) need a big comment explaining why, and b) some justification
> on why this would be a change we'd want to make.
>
> On b, are you seeing any tangible differences with this?
No, just found this by reading source codes.
Regards,
Xiaoguang Wang
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] io_uring: don't hold fixed_file_data's lock when registering files
2020-09-03 4:35 ` Xiaoguang Wang
@ 2020-09-03 11:40 ` Jens Axboe
0 siblings, 0 replies; 4+ messages in thread
From: Jens Axboe @ 2020-09-03 11:40 UTC (permalink / raw)
To: Xiaoguang Wang, io-uring; +Cc: joseph.qi
On 9/2/20 10:35 PM, Xiaoguang Wang wrote:
> hi，
>
>> On 9/2/20 5:32 AM, Xiaoguang Wang wrote:
>>> While registering new files by IORING_REGISTER_FILES, there're not
>>> valid fixed_file_ref_node at the moment, so it's unnecessary to hold
>>> fixed_file_data's lock when registering files.
>>
>> Even if that were the case (I haven't looked too closely at it yet),
>> it would a) need a big comment explaining why, and b) some justification
>> on why this would be a change we'd want to make.
>>
>> On b, are you seeing any tangible differences with this?
> No, just found this by reading source codes.
OK, then I suggest we leave it as it is. The data race analyzers wouldn't
be very happy with it either.
--
Jens Axboe
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-09-03 11:41 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2020-09-02 11:32 [PATCH] io_uring: don't hold fixed_file_data's lock when registering files Xiaoguang Wang
2020-09-02 14:13 ` Jens Axboe
2020-09-03 4:35 ` Xiaoguang Wang
2020-09-03 11:40 ` Jens Axboe
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